Glomus Tumour

Glomus tumors are rare soft tissue neoplasms that typically present in adults (ages 20-40 years) as small, blue-red papules or nodules of the distal extremities, with most cases involving subungual sites. These tumors are typically painful, often causing paroxysmal pain in response to temperature changes or pressure. (See Figures 1 & 2)

Glomus tumors are thought to arise from the glomus body, a thermoregulatory shunt concentrated in the fingers and toes. Most lesions are solitary and localized to cutaneous sites; however, generalized glomuvenous malformations, or multiple glomangiomas, have also been described, and may have extracutaneous involvement.

While the vast majority of glomus tumors are benign, malignant cases have been rarely reported, with such cases typically being locally invasive, and with metastases being exceedingly rare.



A poroma is a benign adnexal neoplasm composed of epithelial cells that show tubular (usually distal ductal) differentiation. The malignant counterpart of a poroma is referred to as porocarcinoma.] Poromas historically have been considered glandular adnexal neoplasms of eccrine lineage, and this view is so entrenched that the neoplasm is often referred to as eccrine poroma; however, analyses by many investigators suggest that poromas can be of either eccrine or apocrine lineage. Apocrine poromas are probably more common than those of eccrine lineage. Poromas can develop in persons of any age, but onset is typically in adulthood.

Poromas belong to the spectrum of acrospiromas, along with nodular hidradenomas, clear cell hidradenomas, dermal duct tumors, and hidroacanthoma simplex


A poroma is a benign neoplasm that shows differentiation toward poroid (glandular ductal) cells. The malignant counterpart of poromas is porocarcinoma, which also shows poroid differentiation. Poromas occur only in the skin and are not known to affect any other tissues.


The prognosis of poromas is favorable because the lesions have no known clinical significance. Even poromatosis (multiple poromas) is not known to be associated with other anomalies. The risk of malignant transformation of a poroma is minimal and is thought to be similar to that of normal skin.


A poroma usually manifests as a solitary papule or nodule. Most lesions are asymptomatic, but minor pain can accompany some lesions. Rarely, the patient develops multiple poromas simultaneously, a phenomenon known as poromatosis. Multiple poromas may be of cosmetic concern and are sometimes disabling, especially if involvement of the sole is noted


Poromas typically are asymptomatic, slow-growing, or stable nodular lesions. Although most are asymptomatic, pain can be a presenting sign. Poromas are one of many types of benign adnexal neoplasms that can manifest secondarily within a nevus sebaceous.

Clinical Features

Poromas typically manifest as skin-colored papules or nodules smaller than 2 cm in diameter. (See Figure 1 Below) Poromas may occasionally manifest as pigmented lesions. Protuberant lesions may exhibit surface erosion or ulceration. Rarely, a poroma manifests in association with nevus sebaceus as a secondary neoplasm.


No procedures (other than simple excision) are applicable to this entity.

Histologic Findings

Like all benign neoplasms, poromas typically show relatively sharp circumscription. (See Figure 2 Below) Most tend to be small, although sizable tumors can be encountered. Poromas are composed of small cuboidal epithelial cells with monomorphous ovoid nuclei and inconspicuous nucleoli. The individual neoplastic cells have compact eosinophilic cytoplasm. (See Figure 3 Below) Areas of ductal differentiation are manifested as tubules lined by a dense eosinophilic cuticle, and, sometimes, cytoplasmic vacuoles can also be seen as an indicator of luminal differentiation. Although poromas can usually be deemed benign based on circumscription and benign cytologic features, these lesions not uncommonly show small foci of necrosis en masse and a highly vascularized (granulation tissue–like) stroma, the combination of which can create concern for malignancy, especially in inexperienced observers.

Poromas manifest several different variations.

Intraepidermal poroma (historically known as hidroacanthoma simplex) represents a form of poroma in which nests of cells with tubular differentiation are confined to the surface epidermis, with no evidence of dermal involvement. This pattern of poromas can sometimes cause confusion with other entities that may exhibit an intraepidermal pattern of growth, including seborrheic keratosis and melanocytic neoplasms.

Figure 1 Poroma on the Toe

Figure 2 Poroma Histology – High Power x200

Figure 3 Poroma Histology Medium Power x100

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