Anaplastic meningioma with rapid growth after omental flap transposition: a case report and experimental study.

Meningiomas occasionally display aggressive behavior, but the mechanisms of malignant transformation remain unclear. We encountered the case of a 65-year-old man with a 10-year history of recurrent meningioma. The patient had undergone multiple tumor resections, radiotherapy treatments, and reconstructive surgeries due to wound infection. After the third resection of the tumor and reconstruction with an omental flap, the tumor demonstrated rapid growth and lung metastasis. The final pathological diagnosis was anaplastic meningioma. Because the drastic change of the tumor was observed after omental flap transposition, we investigated the effect of the omentum on tumor cells and performed histopathological analyses of meningiomas using a mouse model. We found that meningioma cells have a high affinity to the omentum and show a growth advantage when co-cultured with adipocytes. Immunohistochemical staining revealed that meningioma cells adjacent to the omentum strongly expressed fatty acid-binding protein 4, a lipid transfer protein, in both mouse and human. Our results suggest that tumor cells can receive lipid supply from omental adipocytes, and the surrounding tissues may induce tumor progression. We conclude that although omental tissue is an ideal material for reconstruction surgery, close follow-up is recommended in meningioma patients when used for cranioplasty.