Pathological correlation of Magnetic Resonance Imaging features in a classical case of lipomatous meningioma

DNA methylation profiling of a lipomatous meningioma: illustrative case

BACKGROUND

Lipomatous meningiomas are an extremely rare, benign meningioma subtype subcategorized under metaplastic meningioma in the most recent 2021 update to the World Health Organization classification. They make up less than 0.3% of all meningiomas and, to date, less than 70 cases have been reported in the literature, none of which have undergone molecular profiling. This study aims to promote the utility of molecular profiling to better diagnose these rare tumors.

OBSERVATIONS

The authors present the first case of a lipomatous meningioma with DNA methylation profiling that both confirmed its benign biology and uncovered unique cytogenetic changes. Molecular characterization of a lipomatous meningioma confirmed its diagnosis as a distinct, benign meningioma subtype and revealed several copy number variations on chromosome 8 and in NF2 and SMARCB1. Here we discuss some of the radiological and histopathological features of lipomatous meningiomas, how they can be used to distinguish from other meningiomas and other similarly presenting tumors, and a brief literature review discussing the pathophysiology and presentation of this rare tumor.

LESSONS

This study provides evidence supporting the use of molecular profiling to diagnose lipomatous meningiomas and guide their clinical management more accurately.

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.

Lipomatous meningioma: Case report and review of the literature

Lipomatous meningiomas are a very rare form of brain meningiomas consisting of fat accumulation within the tumor. Magnetic resonance imaging (MRI) or computerized tomographic (CT) imaging can be utilized to visualize the fat accumulations, but histopathologic staining is necessary in order to make a definitive diagnosis. The key histopathologic feature is the identification of adipocyte-like cells within the tumor, but other markers have also been identified. In this case report and review of the literature, we discuss how to recognize the symptoms associated with lipomatous meningiomas and the definitive treatment approach for these rare tumors.