Needle aspiration cytology, immunocytochemistry, and electron microscopy in a rare case of secretory carcinoma of the breast in an elderly woman.

Needle aspiration was performed on a breast mass in a 91-year-old woman. The cytologic features in the aspirate were a diffuse, prominent, intracytoplasmic vacuolization and secretion in malignant cells and occasional signet ring-like forms. This was confirmed in a subsequent cell block which was made from the aspirate. Immunocytochemical studies showed a positivity for mucin by alcian blue stain in the vacuolated cells which was periodic acid-Schiff positive and resistant to diastase digestion. Oil-red-O staining was negative and on Colloidal iron stain the tumour cells were positive. Immunopositivity to carcinoembryonic antigen, cytokeratin, and epithelial membrane antigen was found in the malignant cells, while on electron microscopy the tumour cells contained a significant amount of intracytoplasmic secretory material. Secretory carcinoma of the breast is a rare tumour and can be diagnosed and differentiated from other breast carcinomas in view of its characteristic cytologic features.