Primary squamous cell carcinoma of the breast in a pregnant woman: report of a case.

Although reports on primary squamous cell carcinoma of the breast have been increasing in number, the morbidity rate of the disease is comparatively low. Its onset in pregnant women, especially, is quite rare. We herein report a case of primary squamous cell carcinoma of the breast in a pregnant woman. A 33-year-old woman was admitted with a lump in the right breast and an abnormal bloody nipple discharge. The breast mass was 5.6 x 5.4 cm in size, and both ultrasonogram and CT scanning showed that it consisted of a cystic tumor for the most part. A large amount of bloody cystic fluid was aspirated by fine-needle aspiration; squamous cell carcinoma of the breast was suspected by a cytological study on the fluid. Twelve days after an induced abortion was performed, a modified radical mastectomy was carried out. Histological findings of the resected specimen demonstrated that the tumor was squamous cell carcinoma which had been well differentiated with partial keratinization and cancer pearls. Noninvasive ductal carcinoma was also observed in a very small region of the specimen, which indicated that the tumor was probably originally adenocarcinoma which later transformed into squamous cell carcinoma.