A rare subtype of meningioma: Case series of anaplastic meningioma and review of the literature.

ABSTRACT

RATIONALE Anaplastic meningioma, a rare subtype of meningioma, has malignant morphological characteristics and a World Health Organization (WHO) grade of III. PATIENT CONCERNS In this report, we present findings from 6 cases of anaplastic meningioma. DIAGNOSES Pathological examination of the tumors, including hematoxylin and eosin staining and immunohistochemical staining, was performed. Of the six cases of anaplastic meningioma, two were recurrent tumors from original seminoma with a WHO grade of I. Histologically, three cases had carcinoma-like morphology, one case had sarcoma-like morphology, and two had two kinds of tissue structures carcinoma-like tumor cell nests and areas with spindle tumor cells. Necrosis was detected in most cases (5/6). Ki67 index was high and varied from 20% to 70%. INTERVENTIONS: All the patients received surgery. 3 patients received adjuvant radiotherapy. 1 patient received chemotherapy. OUTCOMES: 4 patients had no recurrence at follow-up of 19, 30, 46 and 54 months after the last surgery. 1 patient had recurrence 3 months after the last surgery. 1 patient died 12 days after the last surgery. LESSONS This malignant subtype can be secondary to a WHO grade I meningioma after a long quiescent period. Necrosis was common in the tumor tissues, and Ki67 index was usually high. For patients with a history of meningioma, including benign cases, regular physical examination is important for early detection of tumor recurrence and malignant transformation.