Intracerebral lymphoma deposits: investigation and treatment

In a recently studied series of 12 patients with intracerebral lymphoma deposits, the following are noteworthy: Although most intracerebral lymphoma deposits are dramatically and homogenously enhanced on CT brain scan, this is not always the case; two patients with apparently necrotic centers are presented. Subtraction of enhanced CT brain scanning cuts before and after radiotherapy allow a quantitation of tumor response. The apparent paradox of deficient lymphoma deposit angiogenesis on angiography and good enhancement on CT scan was probed by positron emission tomography (ECAT) in the only patient who did not have a confounding prior craniotomy. ECAT and histopathological examination suggest that the microvasculature of intracerebral lymphoma deposits is rich. The ECAT data demonstrated that regional tumor blood flow was comparable to that in grey matter, but tumor oxygen metabolism was intermediate between grey and white matter. The interesting observation of coupled depression of cerebral blood flow and oxygen metabolism in the cerebrum overlying the tumor and its surrounding edema is discussed. A protracted radiotherapy prescription (with daily fractions of 175 cGy) is favored.