Eccrine porocarcinoma mimicking a venous leg ulcer.

Dear Editors, Eccrine porocarcinoma (EPC) is a rare, malignant skin tumour arising from the ductal portion of eccrine sweat glands and was first described by Pinkus and Mehregan in 1963 (1). With a 20% rate of local recurrence and the potential to metastasize in regional lymph nodes in another 20% of cases (2), EPC often takes an aggressive clinical course (3). Organ spreading is only found occasionally, but with a very poor prognosis (4). EPC arises most commonly (40–50%) on the lower leg, but can also be found in other regions like trunk or neck where a clinical diagnosis can be difficult (5). Moreover, diagnosis can be complicated by the long clinical course which the tumour takes when slowly developing de novo or from a pre-existing, clinically harmless eccrine poroma which can be found by investigation in 20% of cases (6). An 82-year-old male was referred to our department for evaluation of a chronic leg ulcer which first appeared 2 years ago on the right lateral lower leg initially as a scaling plaque. During the 2 years prior to first admission to our clinic, the patient was treated regularly by his general practitioner. Detailed treatment regimen is not known. Two weeks ago, a varicose vein stripping had been performed in an external clinic (details not known). For the first time, a biopsy specimen from the ulcer was taken during this surgical intervention and revealed an eccrine porocarcinoma. Patient’s medical history was clear and he had no current medication. On admission to our department, physical examination revealed an ulcer of the lateral right leg, which was 3 cm × 4 cm in size and had a peripheral erythematous margin. No lymphadenopathy in the inguinal or axillary areas was noted. Initial laboratory studies revealed a normal blood cell count, slightly increased C-reactive protein (5⋅1mg/l; normal < 5⋅0mg/l) and lactatdehydrogenase (290U/l; normal < 200U/l) levels. No clinical signs for an infection were found. Several biopsy specimens were obtained from the ulcerated area and from the livid non-ulcerated margin of the tumour to determine the extent of the lesion. The specimen from the central lesion showed asymmetrical infiltrative cords of basophilic tumour cells with cytologic atypia and atypical mitoses. Together with the focal ductal differentiation these results were concordant with the diagnosis of an eccrine porocarcinoma. A total excision of the ulcerated tumour with a clinical safety margin of 10mm and down to the fascia was performed under local anaesthesia and the resulting defect of 5 cm in diameter was provided with a mesh graft skin transplant from the right upper leg 14 days after when sufficient granulation tissue had appeared. Microscopic examination approved the diagnosis of eccrine porocarcinoma with a vertical tumour thickness of 4mm and showed clear surgical margins. Staging procedures (chest X-ray, abdominal sonography, lymph node sonography) excluded organ or lymph node involvement. The patient remains with no evidence of disease at 6-months follow-up.