Co-Existence of Atypical Meningioma, Intratumoral Lipometaplasia and Extensive Hyperostosis of Calvarium: A Rare Entity

BACKGROUND: Lipomatous meningiomas are a rare variety of meningioma, in which fat storage occurs in adipocytes and lipoblasts are found within the tumor. World Health Organization grade II atypical meningiomas with lipometaplasia and extensive hyperostosis of calvarium is a rare type with a good prognosis after complete removal. CASE DESCRIPTION: Here we report a case of intracranial atypical meningioma with lipometaplasia and disproportionately large hyperostosis of overlying calvarium in a 40-year-old man. His computed tomography and magnetic resonance imaging scans showed right frontotemporoparietal homogenous bony swelling with an underlying diffusely enhancing extra-axial, dural-based lesion with areas of hyperintensity on T1 and isointensity on T2 with perilesional edema. Microscopically, it revealed a meningeal neoplasm with hypercellularity, small cell changes, sheathing pattern, and extensive lipomatous metaplasia. CONCLUSIONS: World Health Organization grade II atypical meningiomas with lipometaplasia and extensive hyperostosis of calvarium is a rare type with a good prognosis after complete removal. Clinical features in patients are similar to those of conventional meningioma; however, radiologic features depend on the amount of fat present in the tumor. To the best of our knowledge, there are no case reports in the current literature regarding this. Every new case will widen our horizon. Meningothelial cells exhibit lipomatous changes as a result of metabolic abnormalities.