Hyperpigmented Paget's disease of the nipple – a diagnostic dilemma

A 62-year-old woman was referred by her GP to the West Sussex Breast Unit with a pigmented lesion on her left nipple that had been increasing in size for six months. She had recently moved back to the UK after living in Australia. She did report recent bleeding from the nipple that had resolved completely. She had no previous breast disease and there was no family history of breast or ovarian cancer. On examination, there was an area of hyperpigmentation of the left nipple measuring 4 × 3 mm with irregular margins, with a couple of bleeding spots on top of this (Figure 1). No breast masses were felt nor was there any evidence of axillary lymphadenopathy. She was referred to dermatology and a diagnosis of possible malignant melanoma was made. She underwent an excision biopsy of the left nipple-areola complex that involved excision of the nipple, areola and central ducts. Immunohistochemistry demonstrated that the tumour cells were strongly positive for Cam 5.2 (Figure 2), cytokeratin (CK) 7 and epithelial membrane antigen (EMA). In addition, Alcian blue and diastase PAS were both positive. Immunochemistry was negative for S-100 and Melan-A. Histopathology demonstrated a 0.7 mm focus of high-grade ductal carcinoma in-situ (DCIS) and oestrogen receptor negative. There was Pagetoid extension along the ducts with involvement of the overlying epidermis. She made a good recovery postoperatively and underwent an MRI scan, six weeks following the initial surgery, that showed no evidence of widespread DCIS or any discrete lumps. A central quadranectomy – wide local excision with removal of nipple-areola complex – was done with Grisotti flap reconstruction. Final histopathology revealed no residual DCIS or invasive carcinoma.