Occult Ductal Carcinoma In Situ Presenting as Benign Papilloma: A Case of Diagnostic Evasion in Bloody Nipple Discharge.

Pathologic nipple discharge in postmenopausal women is a clinical red flag that may conceal underlying malignancy, most notably ductal carcinoma in situ (DCIS), despite often being attributed to benign intraductal papillomas. We report the case of a 59-year-old woman presenting with spontaneous, unilateral bloody nipple discharge. Imaging identified a retroareolar hypoechoic lesion without microcalcifications, suggestive of a benign papilloma, and core needle biopsy revealed no atypia or malignancy. However, due to persistent symptoms and radiopathological discordance, the patient underwent surgical duct excision. Histopathology demonstrated DCIS of cribriform and micropapillary subtypes, confined to the ducts with clear margins. This case highlights the limitations of imaging and biopsy in detecting occult carcinoma within papillary lesions and reinforces the role of surgical excision as the gold standard for both diagnosis and treatment in patients with symptomatic nipple discharge.