Recurrent Sinonasal Fibromyxoid Tumor with Orbital and Intracranial Extension in a 75-Year-Old Woman: A Case Report and Narrative Review of the Literature

Abstract

Sinonasal myxoid tumors are rare and may be difficult to classify, particularly in adults, because much of the recent literature concerns infantile sinonasal myxoma. We report the long-term course of a 75-year-old woman followed since 2016 for a right sinonasal fibromyxoid tumor. Despite several surgical procedures, the tumor recurred repeatedly. During a new resection in 2024, histopathological examination showed a moderately cellular mesenchymal proliferation arising within abundant myxoid stroma. The tumor cells were predominantly spindle shaped and displayed only mild atypia, with no necrosis or atypical mitotic figures; foci of calcification and ossification were also present. Immunohistochemically, the tumor cells showed diffuse vimentin expression, whereas smooth muscle actin and S100 protein were only focally expressed. CD34 and MUC4 were negative, and the Ki-67 proliferation index was approximately 4%. In 2025, the lesion progressed to approximately 70 × 80 × 95 mm, with skull-base destruction, orbital extension, right optic-nerve involvement, frontal intracranial extension, and a midline shift of about 23 mm. A later pathology report referred to the lesion as an “ossifying fibromyxoid tumor,” introducing uncertainty in the final classification. Given the repeated recurrences and local extent, radiotherapy was planned, but the patient was lost to follow-up before treatment delivery could be confirmed. A focused narrative review shows that adult sinonasal myxoid tumors remain less well characterized than infantile forms and that orbitocranial extension is rarely reported. This case illustrates the discrepancy that may occur between bland histologic morphology and markedly destructive local behavior and highlights the value of expert pathologic review when terminology evolves during follow-up.