We report herein on the case of a woman in her late 80 s with mammary squamous cell carcinoma. The ultrasonography showed multiple cystic lesions. Cytology in LBC specimens showed atypical cells with circular-spindle or bizarre morphology, with cell clusters consisting of round cells also being observed. A mix of adenocarcinoma and squamous cell carcinoma was initially suggested from immunostaining with p40. Histologically, the tumor was a mixed type squamous cell carcinoma with solid lesion and three cystic lesions. It was considered that immunostaining of LBC specimens with p40 is a useful method in the cytological diagnosis of the subtype of squamous cell carcinoma.