Primary cerebral lymphoma visualised by means of In-111-pentetreotide scintigraphy

Primary lymphoma of the central nervous system, until recently representing about 1% of all brain tumours, shows a dramatically increased incidence in the general population as well as in high-risk groups (immunocompromised, AIDS), and may rise up to 6% in a population of AIDS patients. The clinical presentation is variable and cannot reliably be distinguished from other i ntracerebral tumours. At present, CT and MRI are the methods of choice for diagnosing cerebral lymphomas. However, their characteristics are not speci fic. The radiological picture may suggest glioma, meningioma, metastatic ca rcinoma or even a cerebrovascular accident. A labelled somatostatin analogue (pentetreotide) has been proposed as a new tracer for the imaging of somatostatin receptors, which have been identifi ed bit immunocytochemical or radioimmunoassay techniques in several organ s ystems. Somatostatin receptors were also identified in surgical biopsy samp les from patients with Hodgkin and non-Hodgkin lymphoma and extra-cerebral lymphoma has already been visualised in vivo by means of In-111-labelled pe ntetreotide. While CT images of the brain showed a regression of the tumour after radiot herapeutic treatment, the scintigraphic images showed persistence of the tu moural tissue, corresponding with the clinical evolution and outcome. Furth ermore, the absence of extra-cerebral lymphoma tissue, seen on the whole bo dy images, was confirmed by post-mortem examination. To our knowledge, this is the first report of a primary intracerebral lymph oma visualised by means In-111-pentetreotide.