Pigmented basal cell carcinoma of the nipple-areola complex mimicking malignant melanoma in a 61-year-old Thai woman: a case report and literature review.

Background: Pigmented lesions of the nipple-areola complex (NAC) are uncommon and may pose a diagnostic challenge because they can mimic malignant melanoma and other NAC conditions. Pigmented basal cell carcinoma (BCC) arising in this sun-protected site is particularly rare and may be overlooked, especially in Asian patients. This case highlights the diagnostic overlap between melanoma-like clinical features and pigmented BCC in the NAC, which can create uncertainty during initial evaluation. Case Description: A 61-year-old Thai woman presented with a 1-year history of a progressively enlarging, asymptomatic hyperpigmented lesion on the left NAC. There was no history of trauma or chronic sun exposure. On examination, the lesion was an irregularly shaped pigmented plaque 1 cm with asymmetry, heterogenous pigmentation localized to the left NAC, raising clinical concern for melanoma based on ABCDE criteria (Asymmetry, Border irregularity, Color variation, Diameter >6 mm); no definite evolution was reported. Mammography and ultrasonography demonstrated focal skin thickening at the lesion site without an underlying breast mass or nodal involvement. Dermoscopic evaluation was not available in our clinical setting and therefore was not performed. A punch biopsy confirmed superficial pigmented BCC. Definitive excision was planned with approximately 4-mm clinical margins; final pathology demonstrated negative margins on all sides, with the closest histologic margin measuring 7 mm. The postoperative course was uneventful, and there was no evidence of recurrence at the 6-month follow-up. Conclusions: Although rare, pigmented BCC of the NAC should be considered in the differential diagnosis of persistent pigmented NAC lesions that mimic malignant melanoma. Systematic clinical assessment, dermoscopic evaluation when available, and timely biopsy when indicated are important to establish the diagnosis and guide appropriate management. Given the short follow-up duration, longer surveillance is required to assess long-term disease control.