Intraventricular inflammatory pseudotumor: report of two cases and review of the literature

Abstract

Inflammatory pseudotumors (IP) are non-neoplastic lesions characterized by collagenous stroma and polyclonal mononuclear infiltrates. It is best characterized in the lung, but can occur in the CNS, mimicking a neoplastic process. We discuss the available literature and our cases in order to elucidate best medical practices when confronted with such a lesion. We report on two cases of intraventricular inflammatory pseudotumor in patients who presented with symptoms of CSF obstruction. Both patients were treated surgically with significant clinical improvement. Histopathologically, both specimens revealed a plasma cell granuloma variant of IP. A Medline search for English articles identified 46 cases of CNS IP, only eight of which were located within the ventricle. As with our case, most patients presented due to CSF obstruction or mass effect. Radiographically, the lesions have a variable appearance although most enhanced with gadolinium. Complete resection was achieved in 67% with a 12% rate of recurrence. With incomplete resection or biopsy alone, progression is seen despite steroid or radiation administration. Malignant transformation was only reported once. CNS IP is a rare pathological entity that cannot be diagnosed through clinical presentation or radiographic characteristics, but rather through a careful neuropathological inspection. The available literature suggests that complete resection with close follow-up is necessary.