Oral basaloid squamous cell carcinoma: A case report with emphasis on histopathological diagnosis criteria.

Basaloid squamous-cell carcinoma (BSCC) is an uncommon variant of squamous cell carcinoma (SCC) consisting of atypical squamous and basaloid cells. It is an aggressive lesion that most commonly affects the oropharynx, being rare in intraoral sites. In this paper, we report the case of a male patient, 42 years old, smoker and chronic drinker, presenting a vegetating and ulcerated leukoerythroplastic lesion, asymptomatic, with five months of evolution, located on the floor of the mouth. Bilateral infarction of the submandibular lymph nodes was observed. Having established the presumptive diagnosis of SCC, an incisional biopsy was performed, which revealed a proliferation of nests and trabeculae of atypical basaloid and squamous cells. Immunohistochemical analysis revealed positivity for AE1/AE3, CK 5, CK 14, p63 and Ki67 (>80%), but negativity for CK7, S-100 and α-SMA. The diagnosis was BSCC. The patient was referred to a head and neck surgery and oncology service for definitive treatment, but died five months after diagnosis. BSCC is a clinicopathological entity whose diagnosis can be challenging. Its aggressive clinical behavior reiterates the relevance of the correct diagnosis for instituting the appropriate treatment. Thus, it is intended, in this work, to discuss the histopathological criteria for differential diagnosis of BSCC, aiming to contribute to its better knowledge and, perhaps, understanding.