Sino-nasal smooth muscle tumours of uncertain malignant potential (SMTUMP) are very rare neoplasms of mesenchymal origin with features in between a benign leiomyoma and a leiomyosarcoma. We report a rare case of SMTUMP in a 44-year-old woman, who presented with vague symptoms of pharyngitis. Nasal endoscopy revealed a smooth mass in left nasal cavity. Contrast-enhanced CT and MRI scans showed features likely to be inverted papilloma or olfactory neuroblastoma or meningioma. Excision was planned and intraoperatively, frozen section revealed a probable spindle cell lesion. Final histopathological report following immunohistochemistry (IHC) & immunofluoresence (IF) confirmed it to be a SMTUMP. This patient underwent complete resection via endoscopic KTP laser assisted, anterior skull base surgery with no recurrence on follow-up.
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