An excisional biopsy revealed that this was an eccrine poroma, a benign neoplasm of sweat gland tissue in the epidermis.
This lesion was clearly not a wart, as it lacked the common verrucous and keratotic features one would expect, and it did not respond to wart treatments. Other diagnoses that might be considered with a lesion like this include pyogenic granuloma, periungual fibroma, and squamous cell carcinoma.
Poromas are well demarcated papules that grow slowly or are stable in size. They are most commonly flesh colored and smooth, but poromas may also appear verrucous, pigmented, or ulcerated. They are usually found on acral skin—particularly the palms or soles. Due to their location, poromas bleed easily, which is what usually prompts patients to seek care. Friable lesions can mimic acral melanoma.
Poromas occur most often in patients over 40 years of age and are evenly distributed among sexes and skin types. Cases have been associated with trauma, radiation, and chemotherapy. Although exceedingly rare, malignant transformation can occur in the form of eccrine porocarcinoma—a larger tumor that can grow rapidly and that has metastatic potential.
Treatment is optional—but desirable—when lesions are painful or bleed easily. Surgical excision is curative. Shave biopsy or curettage coupled with electrocautery of the base is also curative. Recurrence rates are very low with either method of treatment.
In this case, an excisional biopsy of the lateral nail fold was both diagnostic and curative (second image). The patient remained clear 9 months after treatment.
Text and photos courtesy of Jonathan Karnes, MD, medical director, MDFMR Dermatology Services, Augusta, ME. (Photo copyright retained.)