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 intracerebral tumours. At present, CT and MRI are the methods of choice for diagnosing cerebral lymphomas. However, their characteristics are not specific. The radiological picture may suggest glioma, meningioma, metastatic carcinoma 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 identified by immunocytochemical or radioimmunoassay techniques in several organ systems. Somatostatin receptors were also identified in surgical biopsy samples from patients with Hodgkin and non-Hodgkin lymphoma and extracerebral lymphoma has already been visualised in vivo by means of In-111-labelled pentetreotide. While CT images of the brain showed a regression of the tumour after radiotherapeutic treatment, the scintigraphic images showed persistence of the tumoural tissue, corresponding with the clinical evolution and outcome. Furthermore, the absence of extra-cerebral lymphoma tissue, seen on the whole body images, was confirmed by post-mortem examination. To our knowledge, this is the first report of a primary intracerebral lymphoma visualised by means In-111-pentetreotide.