A rare case of sinonasal solitary fibrous tumour in a patient with concurrent papillary thyroid carcinoma: A case report

Introduction and importance: A solitary fibrous tumour (SFT) is a rare neoplasm that commonly arises in the pleura and can occur in other extrathoracic sites. Extrapleural SFT, particularly in the sinonasal cavity, is extremely rare. There are no definite diagnostic criteria for sinonasal SFT as it is rare. Histologic analysis with immunohistochemistry plays an important role in diagnosing SFT. Case presentation: We report herein a case of SFT of the sinonasal cavity, which later spread to the oral cavity in a 67-year-old male with underlying papillary thyroid carcinoma (PTC) stage IV. He complained of recurrent epistaxis from a mass in his left nasal cavity for two weeks. The mass grew bigger, and spread to the oral cavity, causing dysphagia and upper airway obstruction. Tracheostomy was done under local anaesthesia and a biopsy of the mass was taken to rule out metastasis from the PTC. However, histopathological examination revealed a mesenchymal tumour of fibroblastic type, consistent with an SFT. He was planned for surgical resection of the tumour. However, he refused the operation and was lost to follow-up. Clinical discussion: We describe the clinical presentation of this rare tumour of the sinonasal and oral cavity, including upper airway obstruction, and the importance of immunohistochemical markers such as CD34 and BCL-2 in diagnosing SFT. Complete resection of the tumour is the definitive treatment for SFT. Conclusion: SFT of the sinonasal and oral cavity is extremely rare. Upper airway obstruction may occur due to the location of the tumour in the airway region. Immunohistochemistry is crucial to distinguish this tumour from other mesenchymal tumours.