Disseminated Superficial Actinic Porokeratosis

Disseminated superficial actinic porokeratosis, or DSAP, is an inherited skin condition causing dry patches mainly on the arms and legs.

DSAP is a special type of inherited “sun spot” and is sometimes confused with actinic keratoses, but actinic keratoses are more likely to arise on the face and hands.

The tendency to DSAP is inherited as an autosomal dominant characteristic, which means on average half of the children of an affected parent will also have the tendency. However a certain amount of accumulated sun exposure and perhaps other factors such as immune suppression are needed to bring this tendency out.

Who gets DSAP?

DSAP was first recognised in Texas but it is not uncommon in New Zealand. It appears on the sun-exposed skin of people of European descent. It tends to be more prominent in the summer and may appear less prominent in winter. New lesions have been provoked by ultraviolet light in sun lamps.

The average age which patients first notice DSAP is about 35 to 40, and its frequency in affected families increases steadily with age. It is rare in childhood.

A locus on chromosome 12 was found to be responsible for DSAP in a Chinese family (J Invest Dermatol 2000 Jun; 114(6):1071-4).

Clinical appearances of DSAP

The DSAP lesion begins as a 1-3 mm conical papule, brownish red or brown in colour and usually around a hair follicle containing a keratotic (scaly) plug. It expands and a sharp, slightly raised, keratotic ring, a fraction of a millimetre thick, develops and spreads out to a diameter of 10 mm or more. The skin within the ring is somewhat thinned and mildly reddened or slightly brown, but a pale ring may be seen just within the ridge. The ridge itself is sometimes a dark brown. The central thickening usually disappears, but it may persist with an attached scale, follicular plug or central dell.

Sweating is absent within the lesions. Sun exposure may cause them to itch. In sunny areas, lesions may be present in very large numbers and may change from a circular to a polycyclic outline (overlapping circles). In less sunny climates patients have fewer lesions. In a few cases, the centre of the area becomes very red or may be covered by thick scale.

DSAP mainly affects the lower arms and legs and arises more frequently on the lower legs of women than those of men. The forehead and cheeks are rarely affected and it almost never occurs on the scalp, palms or soles.

Development of true skin cancer within a DSAP lesion is very uncommon. However, many patients with DSAP have had significant exposure to the sun and may also have actinic keratoses and other forms of skin cancer.

The diagnosis of porokeratosis is sometimes made by characteristic features on pathology.

Treatment of DSAP

Unfortunately in our present state of knowledge there is no very satisfactory treatment for DSAP. Over the years we have tried:

  • Cryotherapy
  • 5-Fluorouracil cream
  • Imiquimod cream
  • Tretinoin cream
  • Alpha hydroxy acid cream
  • Calcipotriol ointment
  • Oral acitretin
  • Photodynamic therapy

Nothing has proved very effective long term. Most people settle for just having the larger lesions frozen lightly and returning as necessary for further treatments, using a moisturiser to reduce the dry feeling.

Sun protection

Restriction of sun exposure by wearing long sleeves, skirts or slacks and using sunscreens on the legs and arms is believed to reduce the development of new lesions.


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Cutaneous B-cell lymphoma

What are cutaneous B-cell lymphomas?

Lymphomas are tumours of the lymph nodes and lymphatic system. Extranodal lymphomas are tumours that occur in organs or tissues outside of the lymphatic system. When lymphomas occur in the skin with no evidence of extracutaneous disease at the time of diagnosis, they are called ‘primary’ cutaneous lymphomas. There are many different types of primary cutaneous lymphomas but they can be broadly divided into two categories, cutaneous T-cell lymphomas and B-cell lymphomas. Primary cutaneous lymphomas of B cell type comprise approximately 20% of cutaneous lymphomas.

Cutaneous B-cell lymphomas occur when there is a malignant proliferation of lymphocytes of the B-cell type. Mutation occurring at different points in B cell development leads to differing forms of lymphoma.


Classification of cutaneous B-cell lymphomas

In 2005, the World Health Organisation (WHO) and European Organization for Research and Treatment of Cancer Classification (EORTC) reached a consensus classification for cutaneous lymphomas1. It was revised by the WHO in 20082. Primary cutaneous B-cell lymphomas include:

  • Primary cutaneous follicle centre lymphoma


  • Primary cutaneous marginal zone B- cell lymphoma
  • Primary cutaneous diffuse large B-cell lymphoma, leg type
  • Primary cutaneous diffuse large B-cell lymphoma, other

Primary cutaneous follicle centre (FC) lymphoma

These skin lymphomas typically present as solitary or grouped nodules, tumours, or infiltrative plaques. They occur most commonly in the scalp, forehead, neck, trunk and back. The tumours have an indolent (slow growing) course but progress slowly with time. Less than 10% of patients have involvement of non-cutaneous sites. Neoplastic follicle centre cells, usually a mixture of centrocytes (small and large cleaved follicle centre cells) and centroblasts (large noncleaved follicle centre cells with prominent nucleoli) are seen in the dermis in at least part of the infiltrate, but usually spare the overlying epidermis. Cellular morphology may vary with the age and size of the lesion, with care required to differentiate this group from Primary cutaneous diffuse large B-cell lymphoma, leg type.

Primary cutaneous FC lymphoma needs to be differentiated from a secondary cutaneous lymphoma, which is where a nodal follicular lymphoma has spread to involve the skin (skin metastasis). It appears from molecular biology studies that Primary cutaneous FC lymphoma usually lack expression of the bcl-2 protein, and, the t(14;18) translocation, which if present may suggest systemic follicular lymphoma.

Primary cutaneous FC lymphomas may be treated with radiotherapy or combination chemotherapy. Radiotherapy is the treatment of choice for localised tumours whereas multiple tumours on the skin of different parts of the body (multifocal) may respond better to combination chemotherapy. Patients with primary cutaneous FC lymphomas have a good overall survival rate. Five-year survival is reported to be more than 95%.

Primary cutaneous marginal zone B-cell lymphoma

These are low-grade malignant B-cell lymphomas of the MALT (mucosa-associated lymphoid tissue) type, that occur in the skin as solitary or multiple red to brownish red papules, plaques, or nodules. They are usually located on the trunk or extremities, especially the arms. Often the lesions appear minor clinically. Histologically, these lymphomas are characterised by the presence of nodular or diffuse infiltrates with small lymphocytes, marginal zone B cells, lymphoplasmacytoid cells and plasma cells localised in the dermis and subcutaneous fat. This group also includes primary cutaneous immunocytomas.

Primary cutaneous immunocytoma and marginal zone B-cell lymphoma are classed as indolent lymphomas with excellent prognosis. Five-year survival rate is close to 100%. Dissemination to extracutaneous sites is very rare, however there are reports of it spreading to other organs and the bone marrow.

Radiotherapy or surgical excision is effective treatment for patients with a solitary or few lesions. Multifocal skin lesions are treated with chemotherapy agents such as chlorambucil, interferon alpha and anti-CD20 antibody (rituximab). As this is an indolent lymphoma, observation is a reasonable approach in some cases.

Primary cutaneous large B-cell lymphoma, leg type

These cutaneous B-cell lymphomas occur mainly in elderly females and present as erythematous red or bluish-red nodules or tumours usually on one or both lower legs. These tumours are more aggressive than large B-cell lymphomas of the head and neck, often disseminate to extracutaneous sites and have a more unfavourable prognosis. Five-year survival is less than 50%.

Histologically these lymphomas show a diffuse monotonous population of centroblasts and immunoblasts. This picture may be seen in lesions not arising on the leg, and these can be classified into this group. Histochemistry tests are essential to identify this type of lymphoma.

Only some localised small tumours may be treated using radiotherapy. Anthracycline-based chemotherapy is used for most skin tumours or when tumours have spread to other parts of the body. Some cases have shown response to the anti-CD20 antibody rituximab. Death usually occurs with disseminated disease.

Primary cutaneous diffuse large B-cell lymphoma, other

This group contains large B-cell lymphomas arising in the skin, which do not belong to the primary cutaneous follicle centre lymphoma group or large B-cell lymphoma, leg type. These lymphomas commonly present with skin lesions on the head, the trunk or the extremities and have an excellent prognosis.

Intravascular large B-cell lymphoma is a well-defined subtype of large B-cell lymphoma. Malignant B lymphoid cells proliferate within the lumen of small blood vessels, primarily in the skin and central nervous system. Lesions appear as erythematous, tender nodules, tumours, and telangiectases mainly on the trunk and lower legs. There are no abnormal cells outside the blood vessels. Cutaneous lesions may be confused with mycosis fungoides, sarcoidosis, blood vessel tumours, or secondary cutaneous involvement by lymphoma or leukaemia (leukaemia cutis). As the disease progresses secondary organ involvement often occurs. Prognosis is poor, particularly if the disease has spread to other parts of the body.

Blastic plasmacytoid dendritic cell neoplasm

Blastic plasmacytoid dendritic cell neoplasm is a rare and aggressive form of B-cell lymphoma, presenting with bruise-like plaques, nodules and tumours and later progresses to involve the central nervous system. It represents a type of leukaemia cutis.

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Kaposi sarcoma

Kaposi sarcoma is a disease of blood vessels that was considered very rare before the start of the AIDS pandemic. AIDS is due to infection with human immunodeficiency virus (HIV).

There are four types of Kaposi sarcoma:

  • The classic type of Kaposi sarcoma affects elderly men of Mediterranean and Middle European descent and in men in Sub-Saharan Africa.
  • HIV-associated Kaposi sarcoma mainly affects men who have sex with men.
  • Endemic or African Kaposi sarcoma arises in some parts of Africa in children and young adults.
  • Iatrogenic Kaposi sarcoma is due to drug treatment causing immune suppression.

Classic Kaposi sarcoma is rare and unassociated with HIV infection. It most often arises in middle-aged to elderly men of Mediterranean or Jewis descent (less than 10% are women), particularly if they come from a rural environment. They have a higher than expected rate of diabetes mellitus.

In the United States, Kaposi sarcoma was particularly common in the 1980s especially amongst HIV-positive men who had sex with men. It occurs less frequently in intravenous drug users and is rare in women, haemophiliacs or their sexual partners. HIV-associated Kaposi sarcoma is more common in women in some parts of Africa. It has become less common in the US and Europe because of effective HAART treatment for HIV disease.

African Kaposi sarcoma is becoming more prevalent with the rise in HIV infection. It is one of the most common forms of cancer, especially in children, in Uganda and Zambia.

Iatrogenic Kaposi sarcoma is a particular concern for organ transplant patients, especially in geographic areas associated with high levels of infection with KSHV. Most have the virus prior to transplantation, but the drugs causes it to reactivate.

What is Kaposi sarcoma due to?

Kaposi sarcoma is associated with:

  • Infection with Kaposi sarcoma herpes virus (KSHV). This virus is also called human herpes virus 8. It is most often found in men who have sex with men but it can also occur in heterosexuals. Data is emerging that non-sexual modes of transmission can occur, possibly via saliva or arthropod bites.
  • Production of certain cytokines or cell signalling proteins
  • Genetic factors
  • Hormonal factors
  • Immunodeficiency

Kaposi sarcoma is a multicentric and reactive hyperplasia rather than a neoplasm (cancer). Despite its name, it is no longer classified as a sarcoma (malignant tumour of mesenchymal origin).

KSHV may lie dormant, or replicate and cause disease. As well as causing Kaposi sarcoma, it may also be the cause of some forms of non-Hodgkin lymphoma and Casteleman disease.

How does Kaposi sarcoma present?

Kaposi sarcoma presents as red to purplish spots (macules) and raised bumps (papules and nodules) anywhere on the skin or mucous membranes. Initially, the lesions are small and painless but they can ulcerate and become painful. There are various forms.

  • Localised nodular
  • Locally aggressive
  • Generalised lymphadenopathic
  • Patch stage
  • Localised plaques
  • Exophytic lesions
  • Infiltrative plaques
  • Disseminated cutaneous and visceral disease
  • Telangiectatic
  • Keloidal
  • Ecchymotic
  • Lymphangioma-like / cavernous disease

Kaposi sarcoma often starts as flat patches one or both lower legs, often in association with lymphoedema. The patches evolve into plaques, nodule or scaly tumours.

Kaposi sarcoma in association with HIV infection may develop at any time during the course of illness. Generally, the greater the immunosuppression (e.g. with CD4 cell counts less than 200/mm3) the more extensive and aggressive the Kaposi sarcoma will be.

Kaposi sarcoma lesions can also occur internally; in the gut, lungs, genitals, lymphatic system and elsewhere. These internal lesions may cause symptoms e.g. discomfort with swallowing, bleeding, shortness of breath, swollen legs, etc.

Patch stage

Plaque stage

Classic disease

Plaque stage

Diagnosis of Kaposi sarcoma

The appearance of Kaposi sarcoma lesions is often typical but a skin biopsy of a lesion allows a definite diagnosis. The tumour is made up of spindle cells and vascular structures with a characteristic pattern of clefting (vascular slits).

Blood tests may show no abnormality, depending whether there are associated disorders such as AIDS. Anaemia may arise if there is bleeding. KSHS assays or antibody titres to KSHS are difficult to interpret.

Staging and prognosis in Kaposi sarcoma

There have been various attempts to classify Kaposi sarcoma, depending on whether it is localised or disseminated in the skin, and if there is lymph node or internal organ involvement. The degree of immunosuppression present may also be used in staging systems.

Kaposi sarcoma has a variable course. Some patients develop only a few minor skin lesions whilst others have much more extensive external and internal disease. The latter lesions may result in fatal complications, e.g., from bleeding, obstruction or perforation of an organ. Kaposi sarcoma is not curable, but it can be treated and its symptoms controlled.

Treatment of Kaposi sarcoma

In HIV disease, if the lesions are not widespread or troublesome, often the best approach is simply to treat the underlying HIV infection with highly active antiretroviral drug combinations that suppress HIV replication (HAART). These drugs reduce the frequency of Kaposi sarcoma and may also prevent its progression or the development of new lesions. It is not yet clear why this approach works; one opinion is that the improvement in immune function results in reduced levels of tumour growth-promoting proteins.

Iatrogenic Kaposi sarcoma may improve or clear if it is possible to stop immune suppressive medication.

The choice of more specific treatment depends largely on the extent of the disease.

Treating localised lesions

Small, localised lesions are generally only treated if they are painful or they are causing cosmetic problems. It should be noted that lesions tend to recur after local treatments. Treatments include:

  • Cryotherapy with liquid nitrogen


  • Radiotherapy. This is most useful for classic Kaposi sarcoma and is less effective for HIV-associated disease.
  • Surgical excision of individual nodules.
  • Laser therapy, using pulsed dye laser or pulsed carbon dioxide laser.
  • Injection with anti-cancer drugs such as vinblastine
  • Topical application of alitretinoin gel (Panretin®). This drug is not yet available in New Zealand.
  • Electrochemotherapy, a new treatment that uses electrical impulses to enhance effectiveness bleomycin or cisplatin injected into tumours.

Treating extensive or internal lesions with systemic therapy

Combinations of anti-cancer drugs are given, but at lower than usual dosages if there is immunosuppression.

Other chemotherapy treatments that are used in some international centres include bleomycin, etoposide, paclitaxel, docetaxel and liposomal forms of the standard anti-cancer drugs, doxorubicin or daunorubicin. &squo;Liposomal’ means that the drugs are coated in small fat bubbles, or liposomes which allows better absorption, hopefully resulting in fewer side effects.

Immunotherapy includes the use of interferon-alpha and imiquimod, sirolimus and thalidomide.

Clinical trials into a wide range of other therapies are ongoing. Some examples of these are:

  • Photodynamic therapy (a combination of a photosensitiser and light energy)
  • Isotretinoin (a vitamin-A derivative)
  • Bexarotene
  • Cytokine inhibitors
  • The pregnancy hormone, human chorionic gonadotropin (HCG); Kaposi sarcoma lesions disappear in some women when they become pregnant.
  • Ganciclovir, cidovir and foscarnet (antiviral medications) have been recently reported to result in lower rates of Kaposi sarcoma amongst those being treated for CMV retinitis (inflammation of the retina caused by cytomegalovirus) and are currently being studied. Aciclovir, another antiviral, has been tried, but does not appear to work.




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Nodular Prurigo

What is nodular prurigo?

Nodular prurigo is a skin condition characterised by very itchy firm lumps. It is the most severe form of prurigo. It is not known why these lumps appear. It is also called ‘prurigo nodularis’.

Nodular prurigo is very difficult to treat effectively.

Clinical features of nodular prurigo

Nodular prurigo can occur at all ages but mainly in adults aged 20–60 years. Both sexes are equally affected.

The individual prurigo nodule is a firm lump, 1–3 cm in diameter, often with a raised warty surface. The early lesion may start as a smaller red itchy bump. Crusting and scaling may cover recently scratched lesions. Older lesions may be darker or paler than surrounding skin. The skin in between the nodules is often dry. The itch is often very intense, often for hours on end, leading to vigorous scratching and sometimes secondary infection.

Nodular prurigo lesions are usually grouped and numerous but may vary in number from 2–200. Nodular prurigo tends to be symmetrically distributed. They usually start on the lower arms and legs, and are worse on the outer aspects. The trunk, face and even palms can also be affected. Sometimes the prurigo nodules are most obvious on the cape area (neck, shoulders and upper arms).

New nodules appear from time to time, but existing nodules may regress spontaneously to leave scars. Nodular prurigo often runs a long course and can lead to significant stress and depression.

What is the cause of nodular prurigo?

The cause of nodular prurigo is unknown. It is uncertain whether scratching leads to the lumps, or if the lumps appear before they are scratched. The reason for the lumps, the inflammation and the increased activity and size of nerves in the skin is under investigation but remains unknown.

Up to 80% of patients have a personal or family history of atopic dermatitis, asthma or hay fever (compared to about 25% of the normal population).

Nodular prurigo may commence as an insect bite reaction or another form of dermatitis. It has been associated with internal disease including iron deficiency anaemia, chronic renal failure, gluten enteropathy, HIV infection and many other diverse conditions.

In some cases, nodular prurigo has been associated with brachioradial pruritus, which is due to compression or traction of spinal nerves. This theory may explain why local treatment is not always successful. It has been speculated that widespread nodular prurigo may also follow sensitisation of the spinal nerves and that the nodules appear because of scratching.

Investigations in nodular prurigo

A skin biopsy may be useful to confirm the diagnosis of nodular prurigo. Under the microscope, the skin is enormously thickened and may appear quite abnormal, sometimes resembling squamous cell skin cancer. The nerve fibres and nerve endings in the skin are markedly increased in size. The skin is inflamed and there is an increased number of neural mediators known to cause itching and nerve growth.

Direct immunofluorescence looking for antibody deposition in the skin is usually negative. Rarely, the blistering disease bullous pemphigoid can present as nodular prurigo. In this case, immunofluorescence reveals immunoglobulins in the basement membrane zone below the epidermis. The prurigo nodules can be present for weeks or months before any blisters appear.

It is important to identify underlying diseases that are associated with nodular prurigo; blood tests may include full blood count, liver, kidney and thyroid function tests. Patch testing may be worthwhile if contact allergy is considered possible.

Treatment of nodular prurigo

Unfortunately this is one of the more resistant conditions skin specialists are called upon to treat. Local treatments tried include:

  • Emollients applied liberally and frequently to cool and soothe itchy skin – menthol or phenol may be added.


  • Oral antihistamines taken at night to reduce itch and allow sleep.
  • Ultrapotent topical steroid creams. To enhance their effect, apply under occlusion; cover with a plastic or hydrocolloid adhesive dressing and leave this in place for several days.
  • Corticosteroid injections (triamcinolone acetonide 10 – 40 mg /ml) into thicker nodules.
  • Coal tar ointment as steroid alternative.
  • Calcipotriol ointment (topical vitamin D3) may be more effective than topical steroids in some cases.
  • Capsaicin cream, which induces itching and burning until eventually the itch stops completely – it requires repeated applications four to six times daily.
  • Cryotherapy, which may shrink the nodules and reduce their itch.
  • Pulsed dye laser, which may reduce the vascularity of individual lesions.

Antibiotic ointment may be used on individual infected lesions, and oral antibiotics (usually flucloxacillin) are indicated for significant secondary infection.

Systemic treatments that may be helpful for more severe disease are listed below, in no particular order. Combination treatment is frequently recommended.

  • Phototherap (UVB and PUVA)
  • Tricyclic anti-depressants such as amitriptyline or doxepin
  • Anticonvulsants used for neuropathic pain and itch, such as gabapentin or pregabalin
  • Naltrexone, an opiate antagonist (this counteracts the narcotic effect of morphine, heroin and similar drugs), which has been reported to reduce itching in some subjects.
  • Oral steroids
  • Methotrexate
  • Thalidomide which is reserved for very severe cases and may be difficult to access.
  • Ciclosporin, which may reduce the lumps and the itching but its use is limited by side effects.
  • Systemic retinoids such as acitretin or isotretinoin, which may shrink the nodules and reduce the severity of the itch.

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Comedo naevus

What is a comedo naevus?

A comedo naevus is a hair follicle naevus. It is also known as ‘comedone naevus’ and ‘nevus comedonicus’.

A comedo naevus is an unusual type of epidermal naevus, or birthmark (hamartoma), in which there is a localized collection of dilated follicles filled with keratin. It is more accurately termed follicular keratotic naevus, as there are no true comedones

What does comedo naevus look like?

Comedo naevus is usually present at birth or develops in early childhood. Males and females are equally likely to be affected. Lesions often grow more quickly at puberty. They can appear anywhere on the body but are most commonly found on the face, trunk, neck and upper extremeties.

The lesions appear as closely grouped slightly elevated papules with central keratinous plugs so they look like comedones. They may be distributed in a linear, interrupted, unilateral or bilateral pattern and sometimes follow the lines of Blaschko

Comedo naevus

What causes a comedo naevus?

The exact cause of comedo naevus is unknonw, but it is thought to be due to cutaneous mosaicism, i.e. a line of cells with a genetic error. If this error occurs early in development of the embryo, the cells may spread out to cause multiple comedo naevi.

Mutations in FGFR2 have been detected in the naevi of some patients. This is the same gene that has found to be abnormal in a more serious generalised genetic condition, Apert syndrome, so the comedo naevus may be a ‘mosaic’ of Apert syndrome (some cells have the abnormal gene, and other cells have the normal gene). Apert syndrome causes craniofacial dysostosis (abnormalities of the bone structure of skull and face) and other skeletal abnormalities. Patients with Apert syndrome often suffer from severe acne, which also arises within a comedo naevus.

What is comedo naevus syndrome?

Comedo naevus syndrome is when comedo naevus is associated with other medical conditions. Like other epidermal naevi, comedo naevus is rarely associated with other abnormalities of the cell of origin, the embryonic ectoderm. These may include:

  • Cataracts
  • Skeletal anomalies especially affecting fingers and toes or the spine
  • Developmental delay

What is the treatment for comedo naevus?

There is no specific treatment for comedo naevus. Lesions are usually symptomless and treatment is usually sought for cosmetic purposes. Some improvement of lesions may be seen with the use of topical tretinoin, salicylic acid or ammonium lactate lotion.

Surgery and laser treatment may be used if lesions are particularly disfiguring.

What are the complications of comedo navus?

Rarely, at puberty or later, may a comedo naevus develop inflammatory acne-like lesions within it. These can lead to cysts, recurrent bacterial infections, abscesses, and scarring. These should be treated with appropriate antibiotics or surgical drainage. Topical and oral treatment for acne may improve the appearance.

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Erythema Annulare Centrifugum

What is erythema annulare centrifugum?

Erythema annulare centrifugum refers to a number of chronic annular (ring-shaped) and erythematous (red) skin eruptions. Other descriptive terms have been used to classify these types of lesions, including:

  • Annular erythema
  • Figurate erythema
  • Erythema perstans
  • Erythema gyratum perstans
  • Erythema gyratum repens
  • Erythema figuratum perstans


    What are the signs and symptoms of erythema annulare centrifugum?

Erythema annulare centrifugum may occur at any time throughout life, from infancy to old age. The eruption usually begins as small raised pink-red spot that slowly enlarges and forms a ring shape while the central area flattens and clears. There may be an inner rim of scale. The rings enlarge at a rate of about 2–5 mm/day until they reach a diameter of about 6–8 cm. Sometimes the lesions do not form complete rings but grow into irregular shapes. One or several lesions may be present.

Erythema annulare centrifugum most often appears on the thighs and legs, but may occur on the face, trunk and arms. The lesions rarely cause symptoms but in some patients may cause mild itching or stinging.

What causes erythema annulare centrifugum?

Often no specific cause for erythema annulare centrifugum is found. However, it has been noted that erythema annulare centrifugum is sometimes linked to underlying diseases and conditions. These include:

  • Bacterial, fungal and viral infections such as tuberculosis, sinusitis, candidiasis or tinea
  • Drugs including chloroquine and hydroxychloroquine, oestrogen, penicillin and amitriptyline
  • Cancer (especially the type known as erythema gyratum perstans, in which there are concentric and whirling rings)
  • Food, most often blue cheese or tomatoes
  • Recurrent or chronic appendicitis
  • Cholestatic liver disease (blocked bile system)
  • Graves’ disease (overactive thyroid gland)

In these situations, erythema annulare centrifugum resolves once the underlying cause is treated or the offending drug is stopped.

How is the diagnosis of annular erythema made?

The diagnosis of erythema annulare centrifugum is made clinically, and confirmed by histopathology showing perivascular lymphocytic infiltration.

Further investigations may be carried out to exclude other causes of annular rashes and to look for an underlying cause, if any.

What is the treatment of erythema annulare centrifugum?

Erythema annulare centrifugum usually clears up by itself. Eruptions may be last from anywhere between a few weeks to many years (the average duration is 11 months). Most cases require no treatment (and no curative therapy is known). However, topical corticosteroids may be helpful in reducing redness, swelling and itchiness.

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Erythema Multiforme

Granuloma annulare


What is keratoacanthoma?

Keratoacanthoma is a skin lesion that erupts in sun damaged skin, rather like a little volcano. It grows for a few months, then may shrink and resolve by itself. Keratoacanthoma is considered to be a variant of the keratinocytic or non-melanoma skin cancer, squamous cell carcinoma (SCC). As it cannot be clinically reliably distinguished from more serious forms of skin cancer, keratoacanthomas are usually treated surgically.

Keratoacanthoma may start at the site of a minor injury to sun damaged and hair-bearing skin. At first it may appear as a small pimple or boil and may be squeezed but is found to have a solid core filled with keratin (scale). It then grows rapidly and it may be up to 2cm in diameter by the time it is brought to the attention of the doctor.

©R Suhonen

What causes keratoacanthoma?

Keratoacanthoma arises from hair follicle skin cells for unknown reasons.

Some keratoacanthomas appear to be related to infection with human papilloma virus (HPV), the cause of warts, but the majority of keratoacanthomas are not found to be due to HPV.

What is the treatment for keratoacanthoma?

Keratoacanthomas should be treated for several reasons.

  • To obtain pathology: keratoacanthoma can be difficult to distinguish from invasive squamous cell carcinoma.


  • To be rid of an unsightly, tender or worrisome lesion
  • To minimise the scar, this can be more unsightly if the lesion resolves on its own.

Treatment requires destruction of the lesion. Options include:

  • Cryotherapy
  • Curettage and cautery or another form of electrosurgery
  • Excision
  • Radiotherapy

Follow-up for keratoacanthoma

If keratoacanthoma recurs, it should be treated again.

Patients with keratoacanthomas are at risk of further similar lesions and other skin cancers.

Multiple keratoacanthomas

There are some rare conditions in which multiple keratoacanthomas appear. These are:

  • Grzybowski eruptive keratoacanthomas
  • Muir Torre syndrome
  • Multiple self-healing squamous epitheliomas of Ferguson-Smith
  • Keratoacanthoma centrifugum marginatum

Management requires surgery as well as oral medications such as acitretin, methotrexate or cyclophosphamide

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Melanocytic Naevus

What is a mole?

A mole is a common benign skin lesion due to a local proliferation of pigment cells (melanocytes). It is more correctly called a melanocytic naevus (American spelling ‘nevus’), and is sometimes also called a naevocytic naevus. A brown or black mole contains the pigment melanin, so may also be called a pigmented naevus.

A mole can be present at birth (congenital naevus) or appear later (acquired naevus). There are various kinds of congenital and acquired naevi.

Who gets moles?

Almost everyone has at least one mole.

  • About 1% of individuals are born with one or more congenital melanocytic naevi. This is usually sporadic, with rare instances of familial congenital naevi.
  • Fair-skinned people tend to have more moles than darker skinned people.
  • Moles that appear during childhood (aged 2 to 10 years) tend to be the most prominent and persistent moles throughout life.
  • Moles that are acquired later in childhood or adult life often follow sun exposure.

Most white-skinned Australians have 20–50 moles.

What causes moles?

Although the exact reason for local proliferation of naevus cells is unknown, it is clear that the number of moles a person has depends on genetic factors, on sun exposure, and on immune status.

  • People with many moles tend to have family members that also have many moles, and their moles may have a similar appearance.
  • Somatic mutations in RAS genes are associated with congenital melanocytic naevi.
  • New melanocytic naevi may erupt following the use of BRAF inhibitor drugs (vemurafenib,dabrafenib).
  • People living in Australia have many more naevi than their relatives residing in Northern Europe.
  • Immunosuppressive treatment leads to an increase in numbers of naevi.

What are the clinical features of moles?

Moles vary widely in clinical, dermatoscopic and histological appearance.

  • They may arise on any part of the body.
  • Moles differ in appearance depending on the body site of origin.
  • They may be flat or protruding.
  • They vary in colour from pink or flesh tones to dark brown, steel blue, or black.
  • Light skinned individuals tend to have light-coloured moles and dark skinned individuals tend to have dark brown or black moles.
  • Although mostly round or oval in shape, moles are sometimes unusual shapes.
  • They range in size from a couple of millimetres to several centimetres in diameter.

Classification of melanocytic naevi

Congenital melanocytic naevus

Congenital melanocytic naevi are classified according to their actual or predicted adult size in maximum dimension, and on specific characteristics.

Congenital melanocytic naevi
Small congenital naevus Medium congenital naevus Giant naevus Hairy congenital naevus
Small congenital naevus is < 1.5 cm diameter. Medium congenital naevi are 1.5–19.9 cm diameter. A large or giant congenital melanocytic naevus is ≥ 20 cm Hairy congenital naevi grow thick long hairs.
Café au lait macule Speckled lentiginous naevus Naevus of Ota Mongolian spot
Café au lait macule is a flat brown patch. Speckled lentiginous naevus is a flat brown patch with darker spots. Naevus of Ota is a bluish brown mark around forehead, eye and cheek. Mongolian spot is a large bluish mark most often seen on buttocks of newborn.

The pathological classification of melanocytic naevi relates to where naevus cells are found in the skin.

Junctional naevus Dermal naevus Compound naevus Combined naevus
A junctional naevus has groups or nests of naevus cells at the junction of the epidermis and the dermis. A flat mole. A dermal or intradermal naevus has naevus cell nests in the dermis. A papule, plaque or nodule with a pedunculated, papillomatous (Unna naevus) or smooth surface (Miescher naevus). A compound naevus has nests of naevus cells at the epidermal-dermal junction as well as within the dermis. A central raised area surrounded by a flat patch. A combined naevus has two distinct types of mole within the same lesion – usually blue naevus and compound naevus.

Dermatoscopy has given rise to a new classification based on the pigment patterns of melanocytic naevi. Examples include:

Dermatoscopic patterns of melanocytic naevi
Reticular naevus Globular naevus Blue naevus Starburst naevus
Reticular naevus reveal a lattice of intersecting brown lines. Globular naevus characteristically show aggregated brown oval structures. The blue naevus is a uniform structureless lesion, steel blue in colour. Starburst naevus reveals radial lines around periphery of lesion.
Site-related naevus: facial Site-related naevus: acral Naevus with special features Unclassifiable naevus
Facial naevi reveal pseudonetwork around hair follicles Acral naevi (these are on palms and soles) tend to be made up of parallel lines. Naevi with special features include eczematised naevus (illustrated), irritated naevi and halo naevi. The unclassifiable naevus doesn’t have any of the other patterns.

Acquired melanocytic naevus

Ordinary moles that appear after birth may be referred to as acquired naevi. Acquired melanocytic naevi are given a variety of names and there is considerable overlap of descriptions.

Signature naevi are the predominant group of naevi in an individual with multiple moles.

Signature naevi
Solid brown naevus Solid pink naevus Eclipse naevus Cockade naevus
Solid brown naevi have uniform brown pigmentation. Solid pink naevi are seen in fair skinned individuals and lack melanin pigmentation. Eclipse naevus has a ring, or segment of a ring, of darker pigment around a tan or pink centre. Often found in the scalp. Cockade, or naevus en cocarde/cockarde, has a central dark naevus surrounded by concentric circles of light and dark pigmentation like a rosette.
Naevus with perifollicular hypopigmentation Fried-egg naevus Lentiginous naevus Naevus with eccentric pigmentation
Naevi with perifollicular hypopigmentation have white spots around each hair. Easier to see by dermoscopy. Fried-egg naevus is a compound naevus with a flat rim of pigment around a bumpy central portion – the bump can be lighter or darker than the pigmented rim. Lentiginous naevi are small, dark brown or black, flat lesions, often with a slightly paler rim – people with multiple lentiginous naevi have been said to have cheetah phenotype. The Bolognia sign refers to a harmless, small area of darker colour on one side of the naevus.

Uncommon types of melanocytic naevi include:

  • Spitz naevus or epithelioid cell naevus: a pink (classic Spitz) or brown (pigmented Spitz) dome-shaped mole that arises in children and young adults.
  • Reed naevus: darkly pigmented type of Spitz naevus with starburst dermatoscopic pattern
  • Agminated naevi: a cluster of similar moles

The term atypical naevus may be used in several ways.

  • A benign mole that has some clinical or histopathological characteristics of melanoma
  • A mole with specific characteristics: large (> 5 mm); ill-defined or irregular borders; varying shades of colour; with flat and bumpy components.
  • Or, any funny-looking mole; large, or different from the patient’s other moles

Atypical naevi usually occur in fair skinned individuals and are due to sun exposure. They may be solitary or numerous. Pathology is reported as dysplastic junctional or compound naevus and has specific histological features (the Clark naevus).

Acquired melanocytic naevi
Common naevus Naevus in dark skin Atypical naevus Dysplastic naevus
A common naevus is a flat mole with a single uniform colour. In dark skin, naevi are often black in colour. People with multiple atypical naevi are at increased risk of melanoma (cancerous mole). Dysplastic naevus describes an atypical mole that has specific microscopic criteria.
Blue naevus Cellular naevus Miescher naevus Unna naevus
Blue naevus is a deeply pigmented type of dermal naevus. Cellular naevus is a non-pigmented dermal naevus. Miescher naevus is a dome-shaped smooth dermal naevus often found on the face. Unna naevus is a papillomatous dermal naevus that is in the shape of a raspberry.
Meyerson naevus Halo naevus Spitz naevus Reed naevus
Meyerson naevus is a naevus affected by a halo ofeczema/dermatitis. Halo naevus or Sutton naevus has a white halo around the mole. The mole gradually fades away over several years. Spitz naevus or epithelioid cell naevus is a pink (classic Spitz) or brown (pigmented Spitz) dome-shaped mole that arises in children and young adults. Reed or spindle cell naevus is a very 5dark-coloured mole with spindle-shaped dermal melanocytes, usually found on the limbs.
Recurrent naevus Agminated naevus Acral naevus Nail unit naevus
Recurrent naevus refers to the reappearance of pigment in a scar following surgical removal of a mole – this may have an odd shape. An agminated naevus is a cluster of similar moles or freckles. Acral naevus refers to one on the palm or sole. Nail unit naevus causes a uniform longitudinal band of pigment on a nail.

What are the complications of moles?

People worry about moles because they have heard about melanoma, a malignant proliferation of melanocytes that is the most common reason for death from skin cancer

  • At first, melanoma may look similar to a harmless mole, but in time it becomes more disordered in structure and tends to enlarge.
  • People with a greater number of moles have a higher risk of developing melanoma than those with few moles, especially if they have over 100 of them.

Moles sometimes change for other reasons than melanoma, for example following sun exposure or during pregnancy. They can enlarge or regress (disappear).

  • A Meyerson naevus is itchy and dry because it is surrounded by eczema.
  • A Sutton or halo naevus is surrounded by a white patch, and fades away over several years
  • A recurrent naevus is one that appears in a scar following surgical removal of a mole — this may have an odd shape.

How is a mole diagnosed?

Moles are usually diagnosed clinically by their typical appearance. If there is any doubt about the diagnosis, an expert may be consulted in person or with the help of clinical and dermatoscopic images. This is especially true if:

  • A mole changes size, shape, structure or colour
  • A new mole develops in adult life (> 40 years)
  • It appears different from the person’s other moles (a so-called ugly duckling)
  • It has ABCD characteristics (Asymmetry, Border irregularity, Colour variation, Diameter > 6 mm)
  • It is bleeding, crusted or itchy

Most skin lesions with these characteristics are actually harmless when evaluated by an expert using dermatoscopy. Short-term digital dermatoscopic imaging may be used in equivocal flat lesions to check for change over time.

Naevi that remain suspicious for melanoma are excised for histopathology (diagnostic biopsy). Partial biopsy is not recommended, as it may miss an area of cancerous change.

What is the treatment for moles?

Most moles are harmless and can be safely left alone. Moles may be removed in the following circumstances:

  • To exclude cancer
  • The mole is a nuisance: perhaps irritated by clothing, comb or razor
  • Cosmetic reasons: the mole is unsightly

Surgical techniques include:

  • Excision biopsy of flat or suspicious mole
  • Shave biopsy of protruding mole
  • Electrosurgical destruction
  • Laser to lessen pigment or remove coarse hair

Can moles be prevented?

The number of moles can be minimised by strict protection from the sun, starting from birth. Sunscreen alone is not sufficient to prevent new moles from appearing.

At any age, sun protection is important to reduce skin ageing and the risk of skin cancer.

  • The SunSmart Sun Protection Alert advises when protection is required.
  • Cover up. Wear a hat, long sleeves and long skirt or trousers. Choose fabrics designed for the sun (UPF 40+) when outdoors.
  • Apply sunscreen to areas you can’t cover. Choose broad-spectrum high protection (SPF 50+) sunscreens, applied frequently to exposed areas.

What is the outlook for moles?

Most moles that appear in childhood remain forever. Teenagers and young adults tend to have the greatest number of moles. There are fewer in later life because some of them slowly fade away.

To increase the chance of spotting melanoma early, recommend:

  • Self-skin examination monthly
  • Significant changes in moles or new lesions are reported to doctor or dermatologist
  • Regular skin examinations in patients with many moles, atypical naevi or previous skin cancer
  • Total body photography and digital dermatoscopic imaging (mole mapping) for patients at high risk of melanoma, especially if they have many moles

Figure 1 Junctional Naevus (with free melanin)

Figure 2 Junctional Naevus – Mart-1 stain hightlighting naeval (melanocytes) cells

Figure 3 Intradermal Melanocytic naevus showing banal naeval cells in the dermis

Figure 4 Intradermal Melanocytic Naevus with Pigmented superficial nests and Perivascular Melanophages

Figure 5 Congenital Naevus with a polypoid pattern and prominent congested vessels

Figure 6 Blue Naevus consisting of stellate and spindle banal naeval cells with variable pigmentation


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This photo/content belongs to DermNet and the use of this photo/content is in accordance with DermNet’s Creative Commons Attribution-NonCommercial-NoDerivs 3.0 (New Zealand) Licence, available here. No changes were made to this photo/content. Dermnet does not endorse any changes made to photo / content.
For further information, InfinityPATH recommends you visit Dermnet site: https://www.dermnetnz.org/