Intracranial inflammatory pseudotumor: case report and review of the literature

Inflammatory pseudotumor is an uncommon lesion of unknown etiology most frequently involving the lungs and orbits. Primary intracranial inflammatory pseudotumors are exceptionally rare. Herein, we report a case of inflammatory pseudotumor that arises from the central nervous system in a 25-year-old man.The patient presented with numbness in his right arm and right leg. Computed Tomography and Magnetic Resonance Imaging demonstrated a left fronto-parietal lobulated mass with intense contrast enhancement and perilesional edema mimicking a high grade glioma or metastasis. The lesion was removed by complete surgical resection.Pathologic examination showed spindle cell proliferation in a collagenous background with dense infiltrates of mononuclear inflammatory cells.The spindle cells were diffusely immunopositive for vimentin and focally positive smooth muscle actin but the cells did not show glial fibrillary acidic protein, epithelial membrane antigen, synaptophysin, S-100 protein, anaplastic lymphoma kinase-1 protein and CD1a immunoreactivity. Based on the morphologic and immunohistochemical findings, the diagnosis of inflammatory pseudotumor was made. After surgery, the symptoms had disappeared. No recurrence was observed at the eleven-month follow-up.Although rare, inflammatory pseudotumor of central nervous system is important in the differential diagnosis of the tumor-like intracranial lesions. We discuss the etiopathogenetic, diagnostic and therapeutic issues related to this entity, and review the literature.