Pigmented extramammary Paget’s disease: A potential pitfall of misdiagnosis

ABSTRACT

Introduction@#Extramammary Paget’s disease (EMPD) is a rare cutaneous slow growing tumor seen in areas rich in apocrine glands such as the anogenital region while ectopic EMPD is defined as EMPD arising on non-apocrine areas. The pigmented variant of EMPD is a very rare finding, with only a few reported cases, and can be misdiagnosed as melanoma.@*Case report@#We report a case of a 74-year-old woman who presented with a four-year history of pruritic, non- healing erythematous plaques located on the right axilla and left lower abdomen. Histopathology revealed acanthotic epidermis with atypical keratinocytes that was negative for anti S-100 and Melan-A and was positive for carcinoembryonic antigen (CEA), cytokeratin (CK), CK 7 and epithelial membrane antigen (EMA). Patient was managed as pigmented and ectopic variant of extramammary Paget’s disease. Several tests and imaging were done to rule out malignancy. Wide excision with axillary node dissection, bilateral inguinal node dissection, frozen section biopsy and reconstruction using right pectoralis major musculocutaneous flap, split thickness skin graft with left inguinohypogastric drain were done by reconstructive surgery. Frozen section biopsy was negative for S-100, MELAN-A and HMB-45, ruling out malignant melanoma. Patient followed up every month for 6 months after the procedure with no recurrence and lymphadenopathy.@*Conclusion@#This case emphasizes that extramammary Paget’s disease is not a preventable disease and early diagnosis is the key to a favorable diagnosis. Any unilateral eczematous lesion that does not respond to an appropriate course of topical treatment warrants a skin biopsy.