Tc-99m LL-2 Fab' monoclonal antibody imaging in acquired immune deficiency syndrome-related lymphoma

Both systemic and primary central nervous system (CNS) non-Hodgkin's lymphomas (NHL) occur in people with acquired immune deficiency syndrome (AIDS). The radiographic manifestations may be similar to other neoplasms and opportunistic infections that are also found frequently in AIDS. Furthermore, these diseases may coexist with NHL in the AIDS patient.

To evaluate the use of Tc-99m Lymphoscan (the Fab' fragment of the anti-CD-22 antibody LL-2; Immunomedics, Inc., Morris Plains, NJ) in patients with suspected AIDS lymphoma, we studied 7 patients with 35 sites of suspected disease. Six had CNS lesions suspicious for parenchymal brain lymphoma. Each patient underwent planar and single photon emission computed tomography imaging at 3-5 and 18-24 hours after administration of Lymphoscan. Scintigraphic results were compared with results of conventional diagnostic modalities.

Overall, the sensitivity of Lymphoscan was 92% and the specificity was 86%. In brain lesions, there was 100% sensitivity and 100% specificity. Lymphoscan also had 100% sensitivity for sites of lymphomatous lymphadenopathy and for liver involvement. Although less specific in extracranial sites, Lymphoscan was correctly negative in sites of coexisting adenocarcinoma and pneumonia. Two patients had both parenchymal CNS and systemic lymphoma proven by biopsy.

Lymphoscan appears to be a sensitive and specific method for diagnosing CNS lymphoma in AIDS patients. Although slightly less specific in extracranial sites, it may be helpful in differentiating lymphoma from other etiologies in these patients at risk for multiple neoplasms and opportunistic infections.