A 55-year-old woman has a 3 cm breast mass. Core biopsy shows a basaloid tumor with cribriform and tubular patterns, composed of small cells surrounding round, mucinous, or hyaline cores. The tumor is triple-negative (ER-, PR-, HER2-) but has a relatively favorable prognosis compared to other triple-negative breast cancers. What is the diagnosis?

• A Medullary carcinoma
• B Secretory carcinoma
• C Metaplastic carcinoma
• D Adenoid cystic carcinoma ✓

Explanation

Adenoid cystic carcinoma of the breast is a triple-negative tumor with a characteristically indolent course compared to other TNBCs. It shows a distinctive cribriform pattern with basaloid cells surrounding hyaline or mucinous cores. Despite being triple-negative, axillary lymph node metastasis is rare and prognosis is excellent. It is the breast counterpart of salivary gland adenoid cystic carcinoma. Medullary carcinoma shows pushing borders and lymphoplasmacytic infiltrate, not cribriform architecture.

Reference: Rosai and Ackerman's Surgical Pathology, 11th ed.

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Written and medically reviewed by the StethoPrep medical team.