Primary breast carcinoma with features of the follicular variant of papillary thyroid carcinoma

A 61-year-old female patient with no previous medical history presented to our hospital with a palpable right breast mass as well as palpable axillary lymph nodes. Microscopic examination revealed a bifocal primary carcinoma of the breast displaying characteristics similar to that of follicular variant of papillary thyroid carcinoma. Three axillary lymph nodes contained metastases. Immunohistochemical study for TTF-1, Thyroglobulin, GATA-3, ER and PR was consistent with a primary breast carcinoma, excluding the possibility of a metastatic tumor. The above unusual morphological features were caused by improper fixed tissue. Suboptimal fixation may cause tissue artifacts such as shrinkage, streaming, diffusion, vacuolation and nuclear or cytoplasmic changes as well as decreasing tissue antigenicity. Occasionally, altered morphology may mislead to major diagnostic pitfall.