Lipomatous meningioma: A rare subtype of benign metaplastic meningiomas

Fat in the brain: Facts and features

The presence of fat within a lesion in the brain is not only easy to identify on both CT/MRI but also can help narrow the differential. The purpose of this paper is to illustrate the spectrum of common and rare fat-containing lesions in the brain that are encountered in clinical practice. This paper intends to discuss 15 such lesions which are confirmed by MRI findings and histopathological correlation. We divided the spectrum of fat-containing lesions into lesions with adipose cells, lesions with cholesterol-rich content and tumours with lipomatous differentiation/transformation. Knowledge of these common and rare fat-containing lesions is essential for making the right diagnosis or narrowing the differential diagnosis.

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.

Lipoblastoma: Diagnosis and surgical considerations

Lipoblastoma (LB) and lipoblastomatosis (LBS) are uncommon benign mesenchymal tumors of embryonal fat, occurring almost exclusively in infancy and early childhood. These fast-growing tumors have an excellent prognosis if properly treated. Eight consecutive children having pathologically demonstrated LB treated by the same surgical team were retrospectively reviewed. There were 5 boys and 3 girls between 7 to 36 months (median age 22 months). The localization of the tumors was on the thigh (1 case), abdomen (2 cases), axillary and pectoral region (1 case) paragluteal region (1 case), lumbar area (1 case), inguinal-scrotal (1 case), and in one case, presacral, gluteal and perirectal region (1 case). Five were focal and in 3 cases an infiltrative growth pattern was observed. One case exhibited a gross appearance resembling sacrococcygeal teratoma, with associated Dravet syndrome. No recurrence was noted in our series, after a mean follow-up of 28 months post operatory. Despite its rareness, LB must be kept in mind when diagnosing a rapidly growing fatty mass in children. Even when dealing with very large abdominal LB, complete surgical excision is possible, with an excellent prognosis. Due to the relatively high recurrence rate noted in the literature, particularly in LBS, follow-up is extremely important.

Intracranial Metaplastic Meningioma : Clinical and Radiological Characteristics of 11 Cases

OBJECTIVE

Metaplastic meningioma is an extremely rare subtype of World Health Organization (WHO) grade I meningioma. It has distinctive histological subtypes according to its own mesenchymal components. Owing to its scarcity, clinical or radiological features of a metaplastic meningioma are poorly described.

METHODS

Between 2004 and 2018, we analyzed total 1814 cases surgically proven meningioma for 15 years. Among them, metaplastic meningioma was diagnosed in 11 cases. Magnetic resonance images were taken for all patients, and computed tomography scan was taken for 10 patients.

RESULTS

WHO grade I meningiomas were 1376 cases (75.9%), 354 cases (19.5%) in WHO grade II, and 84 cases (4.6%) in WHO grade III meningiomas. Metaplastic meningioma was 11 cases as 0.8% of WHO grade I meningioma and 0.6% of entire meningiomas for 15 years. Among the entire 11 metaplastic meningiomas, five tumors (45%) were diagnosed as a lipomatous subtype with rich fat components, four (36%) as an osseous subtype with extensive bone formation and two (18%) as a xanthomatous subtype. There was no cartilaginous subtype metaplastic meningioma in our study. Lipomatous and osseous metaplastic meningioma have peculiar radiological characteristics according to mesenchymal components.

CONCLUSION

We investigated a rare metaplastic meningioma subtype based on our 15-year surgical experience with meningiomas. Further investigation will be necessary for the clear clarification of tumor nature of this rare tumor.

Extradural en-plaque spinal lipomatous meningioma: A case report and literature review

Background:

Extradural spinal meningiomas are rare, and few appear as lipomatous meningiomas in an “en-plaque” form. The transitional fibroblastic subtype, with lipid accumulation within the tumoral cells, is typically more aggressive and surgically challenging to resect.

Case Description:

A 42-year-old male presented with neck pain and progressive paresthesias in both upper extremities. Based on the radiological findings, the tentative preoperative diagnosis was lymphoma. However, the biopsy confirmed a meningioma. The patient underwent a combined extradural anterior and posterior approach, resulting in full tumor resection. Histopathologically, the final report documented a lipomatous meningioma.

Conclusion:

Extradural spinal lipomatous meningiomas (i.e., “en-plaque”) are rare and typically result in rapid clinical deterioration. The radiological diagnosis may be difficult, while ultrasonography helps to define their extradural location facilitating planning for gross total anterior/posterior excision where indicated.