BSS Should Be Considered in Differential Diagnosis

by Amy E. Hamaker •

What are the imaging characteristics and clinical outcomes of biphenotypic sinonasal sarcoma (BSS)?

Bottom Line: With a significant recurrence rate even with adequate resection, 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.

Background: Despite the consistent and reproducible histologic, cytogenic, and immunophenotypic findings of BSS, there has been limited investigation into BSS clinical outcomes and imaging characteristics. While pathology is required for definitive diagnosis, imaging findings may help focus pathologic analysis, elucidate any necessary additional workup, and guide management.

Study design: Retrospective review of five patients with BSS surgically treated within a tertiary academic healthcare system.

Setting: Mayo Clinic, Phoenix, Ariz.

Synopsis: Median postoperative follow-up was 31.4 months. Two patients developed local tumor recurrences; both recurrences were unifocal and treated with repeat surgical resection. There were no regional or distant tumor metastases, or deaths within the patient follow-up review period. Three out of five cases underwent open resection with a bifrontal craniotomy for removal of tumor. Two of the cases underwent endoscopic resection. In one case of skull base erosion, dura was resected and sampled and was found to be negative for malignancy. In two cases where lamina was eroded, periorbita was resected. No adjuvant therapy was used for primary disease. CT was evaluated in the entire cohort, while gadolinium contrast-enhanced MRI was available in four of the five patients. Median tumor size was 3.8 cm in greatest dimension. In all cases, the tumors were unilateral and centered in the nasal cavity and ethmoid sinus. There was a variable degree of involvement of the adjacent sinuses. In all five cases, the tumors extended to the nasal septum, lamina papyracea, and anterior skull base with variable degrees of erosion through these structures. Bony involvement on CT demonstrated a mixed sclerotic and lytic appearance, with definitive hyperostotic bone identified in four cases.

On MRI, the tumors demonstrated an overall background of T1 and T2 isointensity compared with cerebral gray matter with smaller superimposed foci of dark MRI signal that mostly corresponded to hyperostosis.

Citation: Miglani A, Lal D, Weindling SM, Wood CP, Hoxworth JM. Imaging characteristics and clinical outcomes of biphenotypic sinonasal sarcoma. Laryngoscope Investig Otolaryngol. 2019;4:484–488.