Adenoid Cystic Carcinoma of Breast Associated With an Incidental Radial Scar: A Cyto-Histopathology Correlation

Invasive breast carcinoma of no special type constitutes the majority of breast cancers in women. Special subtypes with distinctive morphology comprise approximately 25% of breast cancers and cause diagnostic challenges. Adenoid cystic carcinoma (ADCC), a salivary gland-type carcinoma of the breast, is an exceptionally rare entity that shares morphological features and genetic mutations with its salivary gland counterpart. Both cytology and histopathological features of ADCC are unique and allow accurate diagnosis even at unusual sites, such as the breast. Basaloid cells in spherical globules, cords, and cylinders filled with eosinophilic hyaline material are diagnostic cytology findings. Histopathology shows cribriform and pseudo-cystic spaces containing hyaline material. ADCC is an indolent tumor with a good prognosis, even though it is triple-negative on immunohistochemistry. Hence, accurate diagnosis of this unusual tumor with good prognosis is crucial to prevent overtreatment of the patient. Here, we present the cyto-histopathological features and immunohistochemical findings of a rare case of adenoid cystic carcinoma of the breast and discuss its association with a radial scar, which is extremely rare.