Primary sinonasal myxofibrosarcoma: a clinicopathological study of five cases and review of the literature.

Myxofibrosarcoma is a malignant pleomorphic fibroblastic sarcoma with variably myxoid stroma, and is characterised by a distinctive curvilinear vascular pattern. In the head and neck area, myxofibrosarcoma is extremely rare, with only a handful of case reports in the literature to date. We report the first case series of primary sinonasal myxofibrosarcoma across two institutions. Among the five cases (2 female, 3 males, aged 52-82 years old), four arose from the maxillary sinus and one from the sphenoid sinus. Four patients received surgical resection and three with adjuvant radiotherapy. The tumours ranged from 2.9 to 5.6 cm in greatest dimensions. All tumours demonstrated extensive myxoid stroma (>50% myxoid component) with a characteristic curvilinear, elongated, thin-walled vasculature with perivascular condensation of tumour cells. All but one were classified as intermediate to high grade myxofibrosarcoma. Among the four patients with follow-up information, three reported no local recurrence or distal metastasis, and one had local recurrence. Myxofibrosarcoma should be included in the differential diagnosis of sinonasal tumours with a pleomorphic spindle cell morphology and a 'null' immunophenotype.