Dermoscopy of Mammary Paget's Disease: A Case Report and Literature Review

Mammary Paget's disease (MPD) is a rare intraepidermal adenocarcinoma affecting the nipple-areolar complex, often misdiagnosed as benign dermatoses like eczema or psoriasis. We report a case of a 63-year-old postmenopausal woman presenting with a one-month history of an erythematous, eczematous plaque over the right nipple-areolar region. Clinical examination revealed partial destruction of the nipple without an underlying breast mass. Dermoscopic evaluation showed pink structureless areas, white scales, and shiny white lines (chrysalis-like structures), suggestive of MPD. Histopathology demonstrated pale-staining Paget cells within the epidermis, and immunohistochemistry confirmed the diagnosis with strong positivity for cytokeratin 7 and human epidermal growth factor receptor 2 (HER2), and negativity for CK5/6, ruling out Bowen's disease. Imaging (mammography, ultrasound, and MRI) showed no evidence of underlying carcinoma. In light of the patient's refusal of surgical intervention, she was treated with topical imiquimod 5% cream thrice weekly for 16 weeks, with moderate clinical improvement. A comprehensive literature review of 16 reported cases revealed variable dermoscopic features depending on pigmentation, with non-pigmented cases showing pink/white structureless areas, white scales, and shiny streaks-features evident in our case. Differentiation from mimics like eczema, psoriasis, and Bowen's disease using dermoscopy is essential for early diagnosis. This case emphasizes the utility of dermoscopy in identifying MPD, even in non-pigmented cases without associated carcinoma. It also highlights the potential role of non-invasive therapies like topical imiquimod in managing selected patients. A clinico-dermoscopic-pathologic correlation is crucial to avoid misdiagnosis and ensure timely treatment. Regular follow-up is recommended to monitor therapeutic response and detect any future neoplastic transformation.