Solitary fibrous tumor of the nasal cavity and paranasal sinuses

Abstract

The solitary fibrous tumor (SFT), also known as benign fibrous mesothelioma or submesothelial fibroma is one of the different types of existing mesothelial tumors. It was originally described in the pleura by Klemper and Rabin in 1931 1 an dwa slate rreferre dt oa sa SF To fth epleur aand peritoneum with no actual mesothelial differentiation. Although the majority of these tumors are originated in the pleura, a number of extrapleural sites with no relationship to mucosal surfaces have been reported; these include the liver, parapharyngeal space, sublingual gland, tongue, vulva ,paroti dgland ,thyroid ,an dlarynx. 2 Th eSF To fthe nasal cavity and paranasal sinuses is extremely rare, with only 22 cases reported in the world literature so far. A 32-year-old man, originally from Mexico City with a family history of type 2 diabetes mellitus and hypertension presented to us with a 2-month history of bilateral nose obstruction, predominantly on the right side, greenish rhinorrhea, general malaise, and fever, all of which partially resolved after numerous medications previously given to him. Physical examination and endoscopy revealed a smooth-textured, grayish mass that completely obstructed the right nasal cavity and pushed the nasal septum toward the left side. Computed tomography showed a large mass that occupyied the entire right nasal cavity and part of the left cavity with remodeling and erosion of the nasal septum and right lateral nasal wall. The mass completely occupied the right ethmoidal sinus and part of the right sphenoidal an dmaxillar ysinuse s(Fi g1) .Administratio no fintravenous contrast revealed heterogeneous hyperdensity of the lesion. Examination of a biopsy specimen reported a benign tumor compatible with Schwannoma and functional endoscopic sinus surgery was performed. During surgery, the nasal mass was found to be originating from the right lateral nasal wall, with great vascularity and intense bleeding when manipulated with microdebrider. Approximately 60% of the mass was resected and was later sent for histopathologic analysis. A benign tumor was observed microscopically, with the presence of spindle-shaped cells with long nuclei and a moderate amount of eosinofilic cytoplasm; some areas showed interstitial dense collagen deposits while some other sabundan thyalinizatio n(Fig s2 an d3) .Fe wscattered dilated blood vessels and horseshoe-shaped vessels were seen, but there was no evidence of atypical cellularity, necrosis, hemorrhage, or an increase in the number of mitosis. Immunohistochemical staining was positive for vimentin ,CD3 4(Fi g4) ,an dCD9 9an dnegativ efo rS-10 0protein, actin and desmin, thus helping us establish a diagnosis for SFT.