Spiradenoma of the breast: a rare diagnostic pitfall in the evaluation of solid-basaloid breast lesions with a dual cell population

We describe an instructive case of breast spiradenoma resembling adenoid cystic carcinoma (AdCC). A 71-year-old woman underwent excisional biopsy of a breast mass after a conclusive diagnosis was unable to be obtained from core needle biopsy showing an AdCC-like pattern. Histopathologically, the lesion demonstrated solid and cribriform foci comprising basaloid cells, luminal cells, and eosinophilic hyaline material, reminiscent of solid-basaloid AdCC, alongside convoluted lumens, stromal edema, lymphocytic infiltration, and c-kit negativity. On molecular analysis, neitherMYB fusion genes norCYLD gene abnormalities were identified. These results were supportive of spiradenoma. Salivary gland – and skin adnexal–type tumors are challenging to diagnose due to morphological overlaps. This case, highlighting histopathological and molecular features, shows that breast spiradenoma can be a diagnostic pitfall among the differential diagnoses of AdCC.
Source: Virchows Archiv - Category: Pathology Source Type: research