Anaplastic and meningothelial meningiomas in a single tumor: A “dedifferentiated meningioma”?

Abstract

The patient was a 74-year-old man, who developed progressive cognitive impairment and gait instability. Neuroradiological examination demonstrated a large and predominantly extra-axial tumor spreading over the bilateral frontal base, indicative of olfactory groove meningioma. The greater part of the resected tumor consisted of a dense, patternless proliferation of large, round or polygonal cells, and compactly fascicular growth of spindle cells. Tumor cells showed markedly anaplastic cytological features. In small areas of the tumor, a typical meningothelial meningioma showing no cellular atypism was found. Both tumor components were closely juxtaposed and no pathological features of an intermediate grade (atypical meningioma) were noted. Shortly after the operation, the patient developed a local recurrence of the tumor and multiple metastases to the cerebrum, bone and skin. Anaplastic meningioma is a rare, highly malignant neoplasm which arises de novo or as a result of the progressive transformation of a low-grade meningioma. The coexistence of anaplastic and low-grade components in a single meningeal tumor has been rarely reported. This dimorphic appearance is reminiscent of "dedifferentiation", a phenomenon infrequently seen in various mesenchymal and salivary gland neoplasms. We think that the term "dedifferentiated meningioma" can be appropriately applied to tumors such as that reported herein.

Double Meningioma: A Case of Two Fibrous Meningiomas Coexisting Isolatedly in Meningothelial Meningioma

“…The term "dedifferentiated meningioma" was recently proposed for the existence of anaplastic and low-grade components in a single meningeal tumor. 15,16) In our case, both subtypes were low grade, not indicating dedifferentiated meningioma.…”

Meningioma transformation to glioblastoma following stereotactic radiosurgery: A case report and review of the literature

“…[4] Shintaku et al reported the dedifferentiation of meningioma with histopathological analysis showing anaplastic and meningothelial meningioma components juxtaposed. [19] Similarly, Osipov et al reported a case of radiation-induced dedifferentiation of a meningioma into an osteosarcoma. [13] Histopathological analysis showed features of a malignant meningioma adjacent to that of an osteosarcoma.…”

“…reported the dedifferentiation of meningioma with histopathological analysis showing anaplastic and meningothelial meningioma components juxtaposed. [ 19 ] Similarly, Osipov et al . reported a case of radiation-induced dedifferentiation of a meningioma into an osteosarcoma.…”