Primary retroperitoneal meningioma: A case report

Primary extracranial meningiomas are rare disease entities, occurring primarily in the head and neck. We herein present a very rare case of primary extracranial meningioma of the retroperitoneum, observed in a 56-year-old man who presented with a retroperitoneal mass measuring 11 cm in its greatest dimension. Histological examination revealed sheets of spindle cells with frequent whorling patterns. The neoplastic cells had abundant light eosinophilic cytoplasm with minimal mitosis or cellular atypism. Immunohistochemical analysis demonstrated diffuse and strong positivity for vimentin and epithelial membrane antigen. Ultrastructural findings revealed abundant intermediate filaments, complex interdigitating cellular processes, and desmosome-like intercellular junctions, all of which are characteristic ultrastructural features of meningiomas. The patient was free of recurrence or metastasis 11 months after surgery. To the best of our knowledge, this is only the second reported case of primary retroperitoneal meningioma.