CT and MR of lymphomatoid granulomatosis of the CNS: report of four cases and review of the literature.

Lymphomatoid granulomatosis is an uncommon disease characterized by a perivascular pleomorphic cellular infiltration and necrosis. CNS involvement occurs in 20% of the cases. CT findings have been described in five of the previously reported cases of CNS lymphomatoid granulomatosis, and include unifocal, multifocal, and diffuse contrast-enhancing supratentorial lesions. We reviewed the CT scans of three patients and the MR image of a fourth patient with histologically confirmed CNS lymphomatoid granulomatosis. The lesions were in the posterior fossa in three of the four cases. Hemorrhage, which was present in three of the four cases, was detected by imaging studies in two and at autopsy in the third. Systemic involvement was present at autopsy in three cases and was clinically suspected in the fourth. A diagnosis of CNS lymphomatoid granulomatosis should be considered when hemorrhagic or posterior fossa lesions occur in patients with constitutional symptoms.