Spindle Cell Sinonasal Rhabdomyosarcoma in a 73-Year-Old Man: A Case Report

Introduction Rhabdomyosarcoma (RMS) is a malignant soft tissue neoplasm differentiating into primitive mesenchymal cells with partial skeletal muscle differentiation. It is rare, especially in the sinonasal cavity. We review available literature on sinonasal RMS and present a case report involving spindle cell sinonasal RMS, one of the rarest subtypes. Case Report A 73-year-old man with months of right-sided epiphora and nasal obstruction had abnormal soft tissue and calcification in the right nasal cavity on computed tomography. Nasal endoscopy revealed a smooth, firm mass involving the inferior turbinate. The mass was removed en bloc via endoscopic partial medial maxillectomy and ethmoidectomy. Gross pathologic examination revealed a mottled red, tan, firm, bosselated, and glistening mass, with irregular fragments of soft tissue and bone. Histologic examination showed a variably myxoid and fibrous neoplasm with hyalinization. Tumor cells were spindled with moderate pleomorphism and low mitotic activity. Immunohistochemistry was extensively positive for desmin and myoD1 and focally positive for smooth muscle actin. A diagnosis of sinonasal RMS, grade 2, was made. Discussion/Conclusion This is the first reported case of spindle cell RMS originating from the inferior turbinate. Sinonasal RMS has the worst prognosis of all primary sites, especially with age older than 65 years, alveolar subtype, primary tumor greater than 5 cm, high stage/group, and distant metastases. While the risk stratification system accounts for surgical and pathologic factors, more research is needed to determine how this guides selection of resection and/or chemoradiation.