Lipomatous meningioma--an uncommon tumor with distinct radiographic findings

Lipomatous meningioma with concomitant acute subdural hematoma--case report--

A 55-year-old man presented with a rare lipomatous meningioma associated with acute subdural hematoma manifesting as sudden onset of severe headache, but no neurological deficit. No evidence of trauma or underlying predisposition to hemorrhage was seen. Fluid-attenuated inversion-recovery magnetic resonance imaging showed a thin hyperintense area in the right temporal convexity, and an extra-axial mass appearing as mixed hypointensity and hyperintensity. Two weeks later, right temporal craniotomy was performed and the tumor was totally resected with the attached dura. The hematoma was localized at the inferior margin of the mass and connected directly with the tumor. Histological examination of the resected specimen revealed typical meningothelial meningioma admixed with mature adipose tissue. Longstanding intratumoral congestion probably caused hyaline deposition in the tissue, leading to vessel rupture.

Lipomatous meningioma

We present a case of intracranial lipomatous meningioma in the parietal convexity in a 64-year-old woman. The mass showed low density on computed tomography, was hyper-intense on T1-weighted magnetic resonance images, and had decreased intensity upon imaging with fat-suppressed sequences. Gross total removal of the tumor was performed. Histopathologically, the tumor was a meningioma with mixed transitional and lipomatous patterns. Immunohistochemically, the meningothelial foci were positive for epithelial membrane antigen (EMA) and vimentin, and negative for S-100 protein. The lipomatous foci were positive for EMA, vimentin, and S-100 protein. The Ki-67 index values of the meningothelial and lipomatous foci were 1.0% and 1.8%, respectively. We review previous reports of lipomatous meningioma and discuss its clinical presentations and pathology.

Lipomatous meningioma: report of 2 cases and review of the literature

BACKGROUND

Lipomatous meningioma is a rare but, most of the time, benign tumor. Its pathogenesis is still debated: it is usually considered to be part of the metaplastic meningioma, but several authors recently suggested that fat accumulation inside the tumor was related to metabolic disorders of the meningothelial cells.

CASES DESCRIPTION

We report 2 cases of lipomatous meningioma. Both patients were women older than 60 years. One patient suffered from headache and seizures, the other one presented with behavioral disturbance. Radiological features depended on the amount of fat accumulation within the tumor. Surgical treatment allowed complete resection in both cases without any complications. Both meningiomas were of transitional-type and were apparently composed of 2 populations of cells: meningothelial cells and lipid-laden cells resembling mature adipocytes. Immunohistochemical study showed that lipid-laden cells expressed EMA, CD99, and progesteron receptor, favoring a meningothelial differentiation rather than an adipocytic lineage.

CONCLUSION

Our study strongly suggests that lipomatous meningioma results from an accumulation of lipid inside meningothelial cells rather than a true metaplasia.

Lipomeningioma: case report and review of the literature

We present a case of histologically confirmed lipomeningioma, the first to our knowledge reported in Australia. A 61-year-old man presented with seizures and confusion, and was found to have a non-enhancing left extra axial temporo-parietal lesion on CT and MRI scan. On MRI, the mass lesion showed hyper-intensity on the T1 weighted images, hypo-intensity on fat suppressed T2 weighted images and no enhancement with intravenous gadolinium, indicating a mass consisting predominantly of fatty tissue. A subsequent CT also showed the mass lesion to be hypodense with Hounsfield units indicating fatty tissue. A durally based tumour with high fat content macroscopically was excised at craniotomy under ultrasound guidance. Post-operative recovery was uneventful. Histology demonstrated a meningioma with high lipid content in the form of mature adipocytes and without atypical features. While not exceedingly rare, fewer than 30 cases of lipomeningioma, lipomatous meningioma, or lipidised meningioma have been reported in the world literature.

Spontaneously T1-hyperintense lesions of the brain on MRI: a pictorial review

In this work, the brain lesions that cause spontaneously hyperintense T1 signal on MRI were studied under seven categories. The first category includes lesions with hemorrhagic components, such as infarct, encephalitis, intraparenchymal hematoma, cortical contusion, diffuse axonal injury, subarachnoid hemorrhage, subdural and epidural hematoma, intraventricular hemorrhage, vascular malformation and aneurysm, and hemorrhagic neoplasm. The second category includes protein-containing lesions, such as colloid cyst, craniopharyngioma, Rathke's cleft cyst, and atypical epidermoid. The third category includes lesions with fatty components, such as lipoma, dermoid, and lipomatous meningioma. Lesions with calcification or ossification, such as endocrine-metabolic disorder, calcified neoplasm, infection, and dural osteoma, constitute the fourth category, whereas the fifth category includes lesions with other mineral accumulation, such as acquired hepatocerebral degeneration and Wilson disease. The sixth category includes melanin-containing lesions, such as metastasis from melanoma and leptomeningeal melanosis. The last category is the miscellaneous group, which includes ectopic neurohypophysis, chronic stages of multiple sclerosis, and neurofibromatosis type I. The above-mentioned lesions are presented with their typical T1-hyperintense images, and the underlying reasons for those appearances in magnetic resonance imaging are discussed.

Cutaneous lipomatous neurofibroma

We report a cutaneous lipomatous neurofibroma on the skin of the left-side parietal area of approximately 9 months' duration in a 67-year-old woman. The regular distribution of adipose tissue throughout the lesion suggested that fat was an integral part of the tumor, not a metaplastic or degenerative process. To our knowledge, this type of lesion has not been documented. The main differential diagnosis embraces neurocristic cutaneous hamartoma, lipoma and its variants, cutaneous meningioma, and neural nevus with fat replacement. We propose that lipomatous neurofibroma of the skin is caused by aberrant development of adipose tissue in a neurofibroma. The lesion originated as pluripotential neural crest cells after migration. This acquired lesion could arise from local stem cells. The old suggestion that neuroectoderm is capable of mesenchymal differentiation may be relevant to the histogenesis of this neoplasm.

April 2001: a 70 year old woman with recurrent meningioma

The April Case of the Month (COM). The contributors report a case of a 70 year-old woman with recurrent meningiomas, one of which showed rhabdoid and lipomatous differentiation. Histopathological study of the first and second previous resections showed only typical meningothelial meningioma. On the third craniotomy, a new tumor specimen showed an admixture of classic meningothelial meningioma with lipomatous and rhabdoid foci. Immunohistochemical studies showed diffuse reactivity for epithelial membrane antigen and vimentin, as well as focal positivity for desmin and smooth muscle actin in the areas with rhabdoid features and S100 protein in the lipomatous foci. The presence of these three different and concomitant histological patterns only in the third surgical resection might support a metaplastic origin and, also, corroborates the concept that rhabdoid features are suggestive of an aggressive behavior.

Lipomatous meningioma: a clinicopathologic study of 18 cases with special reference to the issue of metaplasia

We report 18 cases of lipomatous meningioma occurring in patients aged 14 to 79, most being females (72%). Sixteen were supratentorial and 2 involved the spinal meninges. Follow-up ranged from 1 to 120 months. Fifteen patients were cured with surgery alone and 3 (17%) experienced a recurrence at 7, 8 and 24 months. Of these, one died with disease 4 years after resection of the primary lesion. Histologically, 12 tumors were meningothelial, 3 transitional, 2 showed myxoid stromal changes and 1 was microcystic. The 2 spinal tumors were atypical. The proportion of fatty cells ranged from 10 to 90%. These resembled mature adipocytes or less commonly lipoblasts. Xanthomatous meningothelial cells were also noted in 6 tumors (30%). Both conventional meningothelial as well as lipid-laden cells exhibited epithelial membrane antigen immunoreactivity. In addition, occasional cells resembling mature adipocytes showed reactivity for S-100 protein. Ultrastructurally, lipidization of neoplastic cells varied from intracytoplasmic lipid droplets to a single massive globule. Moreover, lipid-laden meningothelial cells featured interdigitating cell membranes and well-formed desmosomes. Lipid droplets were not membrane-bound. In that metaplasia denotes differentiation of one mature cell type to another, lipid accumulation in meningiomas cannot be considered true metaplasia since their lipid-laden cells retain the immunophenotype and ultrastructural features of meningothelium. We suggest that this distinctive subset of meningiomas be termed "lipidized meningiomas" rather than being included in the metaplastic category.

Secretory meningioma with lipomatous component: case report

A case of meningioma coexisting with both lipomatous and secretory components, the latter characterized by hyaline inclusion bodies, is reported. The neuroradiological features of lipomeningioma are reevaluated, and the possible pathogenetic mechanisms of this unique combination in the present case are discussed.

Lipoblastic meningioma. Case report

We describe the case of a patient presenting a right parietal mass lesion with an heterogeneous aspect on computed tomography, with hyperdense contrast uptake areas and hypodense areas with fat density. The unusual aspect of the lesion prevented preoperative and intraoperative diagnosis. The final histopathological examination revealed a meningothelial neoplasia with adipose differentiation, characterizing a lipoblastic meningioma.

CT appearance of microcystic meningioma

Microcystic meningioma is an unusual variant, which has recently been proposed for inclusion in the WHO Classification of Central Nervous System Tumors. Its unique structure produces findings that may be confusing to radiologist and pathologist alike. A case is reported and the English language literature reviewed.

Development of fat within a meningioma

We report a tentorial meningioma containing fat. Multiple areas of fatty density or intensity in the tumour were seen on CT and MRI, which corresponded histologically to lipomatous components. CT 10 years previously had demonstrated a smaller tumour without evidence of fatty components. We found only five cases in the literature in which fatty density was demonstrated within a meningioma on CT and a lipomatous component histologically proved. Xanthomatous change, with lipid in tumour cells, causes decrease in density on CT, but not to the levels of fat. As both lipomatous components and xanthomatous change show similar intensity on MRI, CT can be helpful in differentiating these two conditions. To our knowledge, our case is the only one in which the advent of fatty tissue was confirmed during follow-up.

Lipomatous meningioma: characteristic computed tomographic appearance

A case of lipomatous meningioma is reported. This is a rare variant of meningioma in which metaplasia of meningoepithelial cells occurs and mature adipocytes are present within the tumour. The heterogeneous attenuation and heterogeneous enhancement visualized on computed tomography (CT) can mimic necrotic malignant tumours. However, the demonstration of fat attenuation within the tumour explains the heterogeneity and suggests a benign process. The differential diagnosis of an extra-axial fat-containing tumour should include lipomatous meningioma.