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Clinicopathological Cases: Summaries of Papers

CPC-1 Recurrent malignant porocarcinoma presenting as carcinoma erysipeloides S. Attili, A. Waters, A. Evans and C.J. Fleming Ninewells University Hospital & Medical School, Dundee, Tayside, U.K. Eccrine porocarcinoma (EP) is a rare malignant tumour arising from the intraepidermal eccrine sweat duct epithelium, and accounts for 0Æ005–0Æ01% of cutaneous malignancies. These tumours have a reported local recurrence rate and lymph node metastases of 11.7% and 9Æ6%, respectively. We present a patient with a deeply pigmented EP, occurring at a site of previous radiotherapy. A 77-year-old woman presented with a 1-year history of a warty pigmented lesion on the left breast. Her GP initially diagnosed a seborrhoeic keratosis and treated the lesion with cryotherapy, with no effect. The lesion subsequently enlarged and ulcerated. She had a history of invasive ductal carcinoma of the breast, treated successfully with wide local excision and radical radiotherapy 5 years earlier. Her recent mammogram was normal and there was no clinical evidence of breast tumour recurrence. Examination revealed a 13 · 5 mm ulcer just lateral to her mastectomy scar, with a raised warty pigmented margin. Histology suggested an invasive malignant tumour arising from a population of atypical epidermal cells. The epidermal component showed prominent nesting and clear evidence of dysplastic change, consistent with an intraepidermal poroma. The ulcerative invasive component consisted of small cords and nests of pleomorphic cells showing more marked cytonuclear atypia, and extending into the deep reticular dermis to a depth of 2 mm. Dendritic melanocytes were identified within the tumour. Primitive intracytoplasmic lumina and poorly formed ductal structures were identified, in keeping with an EP. The lesion was completely excised with 4-mm margins. Nine months later she presented with carcinoma erysipeloides histologically due to recurrent EP, with no evidence of recurrence of breast cancer. EP typically presents as endoexophytic tumours on the lower limbs of elderly women and are often ulcerated. Ductal differentiation is usually necessary to identify the tumour histologically. Treatment is by wide excision. Mohs’ micrographic surgery may be useful in cases with a prominent infiltrative growth pattern. However once metastasized, prognosis is poor, with a reported mortality of >50%. EP lesions may be pigmented and have been reported to arise within seborrhoeic keratoses, but this is uncommon (Johr R, Saghari S, Nouri K. Eccrine porocarcinoma arising in a seborrhoeic keratosis evaluated with dermoscopy and treated with Mohs’ technique. Int J Dermatol 2003; 42: 653–57). Radiotherapy is a recognized risk factor for several skin tumours. EP following distant radiotherapy has been reported (Kose R, Coban YK, Ciralik H. Eccrine porocarcinoma arising from preexisting eccrine poroma of the scalp after radiotherapy for cervical cancer. Dermatol Online J 2006; 12: 18). This is the first case to report occurrence of EP following local radiotherapy. We cannot be sure if radiotherapy played a pathogenic role in our patient, or was simply coincidental.