Intracranial inflammatory pseudotumor: report of a rare case.

Inflammatory pseudotumors (IPs) arising in the CNS (IP-CNS) are quite rare. We report here a case of IP in a 5-year-old boy. Intraoperatively there was a well-defined extra-axial lesion in the right frontobasal region with CSF all around. There was no dural attachment. The tumor was removed piece-meal. On pathological examination, the lesion was well circumscribed and comprised of spindled cells in a collagenous background with sprinkling of inflammatory cells. The case was worked up considering the possibilities of low grade glioma, lymphoplasmacyte-rich meningioma, fungal/tubercular infection or inflammatory pseudotumors. Appropriate immunohistochemical stains were performed to rule out the rare possibility of lymphoma or plasmacytoma. The spindled cells were diffusely immunopositive for vimentin and only occasional cells were positive for smooth muscle actin (SMA). The cells did not show anaplastic lymphoma kinase-1 immunopositivity. Based on the above morphological and immunohistochemical analysis, a diagnosis of inflammatory pseudotumor was rendered.