Sinonasal (Schneiderian) Tumors in the Temporal Bone: Case Series and Systematic Review

BACKGROUND: Neoplasms derived from the sinonasal epithelium are a rare finding in the temporal bone, and their origins are controversial. PURPOSE: To review the characteristics of sinonasal epithelial (previously known as Schneiderian) tumors occurring in the temporal bone. DATA SOURCE: This was a 2-center case series and systematic review of MEDLINE, EMBASE, and the Web of Science through May 2021. STUDY SELECTION: Patients with clinicopathologic evidence of temporal bone involvement by neoplasms of sinonasal epithelial origin were selected, with or without a history of prior primary sinonasal epithelial tumors. DATA ANALYSIS: Clinical, radiologic, and pathologic data were extracted. DATA SYNTHESIS: The systematic review included 56 studies and our 8 unpublished cases, totaling 76 cases of papillomas or squamous cell carcinomas in the temporal bone. Of these, 51% occurred secondary to sinonasal tumors, and 49% occurred primarily. Secondary tumors were usually metachronous (77%), with a median delay of 1?year from sinonasal-to-temporal bone tumor diagnosis. Most cases were unilateral (90%); bilateral temporal bone involvement occurred only as secondary (?trilateral?) tumors. Unilateral secondary tumors had ipsilateral (81%) or bilateral (19%) sinonasal counterparts. Secondary tumors were more likely to be malignant (OR, 6.7, P? LIMITATIONS: The review was based on case reports and small case series, which are subject to reporting bias. CONCLUSIONS: The observed tumor patterns support the hypothesis that the Eustachian tube facilitates the spread of sinonasal epithelium?derived neoplasms from the sinonasal cavity to the temporal bone. Transtubal spread of sinonasal epithelium?derived neoplasms should be considered among the rare causes of middle ear masses.