Basaloid squamous cell carcinoma in the mandibular alveolus: A rare case report with differential diagnosis.

Basaloid squamous cell carcinoma (BSCC) is a distinct, high-grade variant of oral squamous cell carcinoma (OSCC) with a poor prognosis. In the head and neck region, the most common sites are the epiglottis, piriform sinus, and tongue base. Other less common sites include the floor of the mouth, oral mucosa, palate, tonsils, nasopharynx, and trachea. In the present report, the unusual case of a 69-year-old male is presented; the patient exhibited ulceroproliferative growth involving the lower alveolus. Incisional biopsy was done and the hematoxylin and eosin-stained sections revealed tumor islands with dysplastic oral epithelial cells invading the underlying connective tissue as islands, cords, and nests. The presence of palisading basaloid cells with a central area of comedo necrosis and keratin formation on the islands revealed the diagnosis of BSCC. Immunohistochemistry demonstrated positive staining for proliferative cell nuclear antigen (PCNA) and pan-cytokeratin. The patient is still under treatment and follow-up.