Squamous cell carcinoma of the breast as a clinical diagnostic challenge.

Squamous cell carcinoma (SqCC) of the breast should be differentiated between the primary skin keratinizing squamous carcinoma and squamous metaplastic cancer. In the current study, the cases of two patients who were diagnosed with SqCC originated from skin and the breast were discussed. A fine-needle aspiration biopsy confirmed the presence of atypical squamous cells. In both cases, the microscopic examination of the surgical specimen revealed a malignant neoplasm differentiated into SqCC characterized by keratinizing cancer cells with abundant eosiphilic cytoplasm with large, hyperchromatic vesicular nuclei. Immunohistochemical studies showed negative for progesterone and estrogen receptors and human epidermal growth factor receptor 2. Moreover, negative expression of cytokeratin 7 and 20 was confirmed. The diagnosis of the both tumors was established based on the detailed analysis of clinical, macroscopical and microscopical information. SqCC localized in the breast is a great diagnostic challenge in pathomorphology and more attention should be paid for analysis of such lesions in daily practice.