Inverted papilloma-like sinonasal epithelial hyperplasia, overshadowing underlying sinonasal fibrosarcoma: a diagnostic pitfall

Proliferating invaginations of the sinonasal epithelium, simulating inverted papillomas, have been mentioned once in the literature as a reactive phenomenon overlying sinonasal fibrosarcomas. These proliferations may be so marked as to make the distinction from inverted papilloma virtually impossible. The possible result is that the examining pathologist's attention might be drawn exclusively to the epithelial component, thus causing him to overlook, especially in a small biopsy, a rather bland but distinctive sarcomatoid component which is located underneath. We report such a case of marked endophytic proliferation of sinonasal epithelium which was interpreted, in the preoperative biopsy, as an inverted papilloma with dense fibrous stroma which later, in the surgical specimen, was found to be a part of a submucosal fibrosarcoma. The diagnostic pitfall is discussed.