Leiomyosarcoma (LMS) is a malignant tumor of smooth muscle origin frequently found in the uterus and digestive tract. However, LMS makes up only 2.3% in the head and neck. Furthermore, LMS of the sinonasal cavity are very rare. It has been shown that LMS isolated to the head and neck are more aggressive and carry a poorer prognosis than gastrointestinal variants. Initially, LMS should be treated by extensive surgical excision, long-term follow-up is essential due to the high rate of local recurrence. Here we present a case of malignant transformation of leiomyoma originated from inferior turbinate and discuss appropriate treatment. 63-year-old woman presented with complaints of rhinorrhea. She had previously undergone excision of a mass originated from the left inferior turbinate at another hospital in 2012, with a biopsy confirming leiomyoma. Upon inspection in the operating room, a small mass was excised from the left inferior turbinate, and the biopsy result revealed leiomyosarcoma. After surgery, she received a total of 30 sessions of radiation therapy and has since been under follow-up without recurrence.