Diagnostic approach to a rare case of anaplastic meningioma with osteosarcomatous differentiation and associated bone alterations

Anaplastic meningioma with osteosarcomatous differentiation is a very rare finding. We herewith present squash cytology, histopathology and immunohistochemistry findings of this rare case with systematic approach to diagnosis. A 38-year-old female presented with complaints of headache, vomiting, seizure with loss of consciousness and left side weakness. Radiologically, there was a heterogeneous hyperintense likely extra axial densely calcified solid lesion measuring approximately 4.2×4.1×3.5 cm along right high frontal convexity compressing the adjacent brain parenchyma. Histology sections revealed fibro collagenous tissue, devitalized bone, multiple vascular spaces lined by fibrous septa with giant cells, along with spindle cell and round proliferation at one end with vague whorl formation. High mitosis, (>20/10 hpf) along with malignant lacy osteoid closely abutting the highly pleomorphic cells were indicative of a malignant spindle cell neoplasm with osteosarcomatous differentiation. Systematic approach, immunohistochemistry with involvement of all the specialities involved led to the correct diagnosis and management of patient.