Mucocele-like tumors of the breast. Cytologic findings in two cases.

Mucocele-like tumors of the breast originally were reported by Rosen in 1986 as benign lesions that histologically resembled colloid carcinoma of the breast. The authors document two cases of mucocele-like tumors to illustrate the difficulty in separating these lesions from colloid carcinoma on the basis of fine-needle aspiration biopsy. Cytologically, mucocele-like tumors contained abundant mucin, few clusters, and sheets of regular epithelium that lacked nuclear atypia, and they contained no intact single cells. The authors recommend open surgical biopsy when fine-needle aspiration biopsy findings in such cases are equivocal.