EXTREMELY WELL-DIFFERENTIATED SQUAMOUS-CELL CARCINOMA OF THE BREAST -REPORT OF A CASE WITH A COMPARATIVE-STUDY OF AN EPIDERMAL CYST

BACKGROUND: Although the cytologic diagnosis of malignancy by fine nee dle aspiration is easy in cases of moderately to poorly differentiated squamous cell carcinoma in various organs, it is not always easy in c ases of the well-differentiated type. CASE: A 46-year-old female prese nted with a slowly growing mass in the right breast; it was diagnosed as an extremely well differentiated squamous cell carcinoma. The diagn osis of malignancy was initially not established by fine needle aspira tion cytology because of minimal cellular atypia. The smear contained many squamous cells, mainly of the superficial type, with little cellu lar atypia, in a background of horny material. However, neither anucle ar superficial cells nor granular cells were found. CONCLUSION: Absenc e of anuclear keratinized cells and granular cells is probably a helpf ul finding for distinguishing squamous cell carcinoma from epidermal c yst in the breast region.