Invasive adenocarcinoma arising in extramammary paget’s disease – a case report and review of the literature

Abstract

Introduction Extramammary Paget’s disease (EMPD) is a rare entity accounting for only 6.5% of all cases of Paget’s disease. EMPD can be difficult to differentiate from some intraepidermal squamous and melanocytic lesions in H&E stained sections. Case report An 86-year-old male with no significant past medical history presented with a supra-pubic skin rash for the last 14 months which was diagnosed by a dermatologist as an eczema. The patient was on topical steroid, which was unhelpful. The patient underwent an incisional biopsy followed by wide local excision. Pathological findings Macroscopically there was an irregular pale tan patch (60 × 55 mm) with a central depressed region (8 × 7 mm and 5 mm deep). Microscopically there were intraepider-mal and dermal clusters of large cells with abundant pale granular cytoplasm, large vesicular nuclei, prominent nucleoli and scattered mitosis. The lesion extended into the reticular dermis and showed occasional gland formation. There was no lymphovascular or peri-neural invasion. The margins were clear. A diagnosis was made of invasive adnexal adenocarcinoma involving the dermis with extensive overlying extramammary Paget’s disease. Discussion Extramammary Paget’s disease usually affects sites with a high density of adnexal glands, such as the anogenital region. Rare sites of involvement include axilla, the glans penis, buttock, thigh, knee, umbilicus, abdomen, scalp and lower anterior chest. Immunohistochemistry and special stains are helpful in confirming glandular differentiation and excluding a squamous or melanocytic lesion.