A clinicopathological study of diagnostically challenging meningioma mimics.

The occurrence of neoplastic and nonneoplastic dural based masses that mimic meningiomas is infrequent and may not be considered during radiological and intraoperative analysis. We describe single institute study of 20 such rare cases. This study included total of 20 cases of meningioma mimics. The clinical, radiological and histopathological findings were evaluated. Tissue fixed in 10% formalin was routinely processed and 5 μ thick sections were cut and stained with hematoxylin & eosin. Histochemistry and immunohistochemistry using avidin-biotin complex immunoperoxidase method was done wherever indicated. In the present study group, 15 were male and 5 female with a male: female ratio of 3:1. The age ranged from 14 to 78 years. Radiologically all these lesions were extra-axial in location, predominantly hypointense on T2W, isointense on T1W images and showed intense homogenous enhancement on contrast administration. Four cases were in pediatric age group with histopathological diagnosis of Rosai Dorfman disease, medulloblastoma, hemangiopericytoma and malignant melanoma. In the adult population, the histopathological diagnoses were hemangiopericytoma, undifferentiated sarcoma, extraskeletal osteosarcoma, Rosai Dorfman disease, medulloblastoma, and metastases from systemic malignancies. Of the total 6 cases of metastases 1 was nonseminomatous germ cell tumor from a primary in testis, 1 was adenocarcinoma from an unknown primary, and 4 were adenocarcinoma from lung. There was a single case of dural based frontal lobe malignant melanoma with congenital hairy nevi on anterior chest wall, scalp, anterior abdominal wall and inguinal region. As the management and biologic behaviour of many of the MM are different, it is essential to familiarize ourselves to them.