Primary pure squamous cell carcinoma of the breast diagnosed by fine-needle aspiration cytology: a case study using liquid-based cytology.

Pure primary squamous cell carcinoma (SCC) is an extremely rare type of breast tumor. We report one of such cases in a 32-year-old woman, diagnosed by fine-needle aspiration cytology (FNAC). Aspiration smears were characterized by squamous cells, both isolated and in aggregates, at various stages of maturation. The tumor was excised, and the histologic sections confirmed the cytologic diagnosis. Pure primary SCC of the breast has a distinctive cytomorphologic appearance, and diagnosis of this tumor by FNAC is possible. For its diagnosis, the exclusion of SCC of local cutaneous structures and metastasis of distant squamous carcinoma are mandatory.