Sphenoid sinus basaloid squamous cell carcinoma presenting as a sellar mass: report a case with review of the literature

Abstract

Basaloid squamous cell carcinoma (BSCC) is a distinctive variant of squamous cell carcinoma (SCC) with more aggressive behavior. It occurs preferentially in the upper aerodigestive tract. Sinonasal tract BSCC is uncommon, and only limited studies have been reported in literature. In these studies, most BSCCs arose from the nasal mucosa with or without extension to the paranasal sinuses. Rare reported cases of BSCC involved only the paranasal sinus. In this report, we present a case of a female patient with a sphenoid sinus mass. Clinically, the patient had progressively decreasing vision and headache. Magnetic resonance imaging (MRI) and computerized tomographic (CT) scan showed an infiltrating tumor mass involving the sphenoid sinus and the sella with compression of the optic nerve. Pathologic examination revealed an invasive basaloid epithelial neoplasm that was arranged in lobules, nests and cords. The tumor also showed palisading of peripheral cells, focal abrupt squamous differentiation and in situ carcinoma in the surface mucosa. In the immunohistochemical studies, this tumor revealed a strongly positive nuclear staining for p63. The morphologic and ancillary studies indicated a BSCC. To the best of our knowledge, this is the first report of sinonasal tract BSCC that mainly involved the sphenoid bone and sella. In this region, BSCC should be distinguished from benign and malignant neoplasms that more often affect sella and base of skull, such as pituitary adenoma with extensive necrosis, small cell neuroendocrine carcinoma (SCNC), olfactory neuroblastoma, malignant germ cell tumor, paranasal adenoid cystic carcinoma (ACC), and a variety of metastatic malignancies.

Fig. 1

Sagittal (a) and cross (b) MRI views revealed a large contrast enhancing mass invading the sphenoid bone, entire sella and compressing the apices of the orbits

Fig. 2

a Light microscopy revealed squamous dysplasia and carcinoma in situ of the mucosal surface (Hematoxylin-eosin stain, original magnification 100×). b Light microscopy revealed an invasive BSCC. The BCSS grew as nested lobules in a fibrotic background. Large lobules showed compacted nests with a jig saw-like pattern (Hematoxylin-eosin stain, original magnification 40×). c In this region, the BSCC grew as cords and trabeculae with peripheral palisading (Hematoxylin-eosin stain, original magnification 100×). d In a high power view, the tumor was composed of closely packed, moderately pleomorphic basaloid cells with hyperchromatic nuclei and scant cytoplasm (Hematoxylin-eosin stain, original magnification 200×). e An immunohistochemical stain for p63 revealed a strongly positive nuclear stain in the tumor cells (original magnification 100×)