Imaging characteristics and clinical outcomes of biphenotypic sinonasal sarcoma

OBJECTIVES: Biphenotypic sinonasal sarcoma (BSS) is a new, rare tumor characterized by concomitant neural and myogenic differentiation. The aim of this study is to describe the imaging characteristics and clinical outcomes of this neoplasm. METHODS: A retrospective review of BSS patients surgically treated within a tertiary academic health care system was performed. Imaging characteristics and clinical outcomes were reviewed. RESULTS: Five patients underwent surgical resection of BSS tumors. Negative surgical margins were achieved in four (80%) patients. There were no deaths but two (40%) patients developed local recurrences during the postoperative follow‐up period (median follow‐up 31.4 months). Review of imaging characteristics revealed a median tumor size of 3.8 cm in greatest dimension. All tumors were unilateral and centered within the nasoethmoidal region. In all cases, the tumors extended to the nasal septum, lamina papyracea, and anterior skull base with variable degrees of erosion through these structures. On CT, involved bony structures demonstrated mixed lytic and sclerotic pattern, with definitive hyperostotic bone identified in four (80%) cases. On MRI, tumors were isointense‐to‐mixed iso/hypointense on both T1‐ and T2‐weighted sequences with one tumor demonstrating mixed T2 hyperintensity. All cases demonstrated gadolinium contrast enhancement. CONCLUSIONS: BSS is a locally aggressive tumor with a low risk of regional or distant metastases but has a significant rate of recurrence even with adequate resection. Despite its rarity, BSS should be considered in the differential diagnosis when imaging demonstrates a unilateral nasoethmoidal mass that is predominantly isointense to cerebral gray matter on T2‐weighted MRI and is hyperostotic on CT. LEVEL OF EVIDENCE: 4