Somatostatin receptor scintigraphy of malignant lymphoma--current status.

Somatostatin receptors have been demonstrated on normal as well as activated human lymphocytes in the circulation and within the reticuloendothelial system such as Peyer's patches and the spleen [1]. Also, lymphocyte function such as proliferation and immunoglobulin synthesis has been showed to be affected by somatostatin [2]. Following the demonstration of the presence of high-density somatostatin receptors in a variety of neuroendocrine derived tumors [3], Reubi et al. subsequently reported visualizing non-Hodgkins lymphoma in four patients imaged with Indium-I1l-[DTPA-DPhel]-Octreotide, an analogue of somatostatin [4]. Autoradiography utilizing 125I-[Tyr3]Octreotide was used to demonstrate the diffuse distribution of somatostatin receptors in tissue samples of biopsies taken of the involved sites.They suggested that somatostatin receptors could be used as valuable pathobiochemical tissue markers and potentially useful as an in vivo diagnostic tool for human malignant lymphomas. In ten patients studied with malignant lymphoma (Hodgkins disease and non-Hodgkins lymphomas), lymphoma deposits could be demonstrated [5]. In four patients, additional tumor localizations were observed as compared to the results of combined physical and radiological (CT and ultrasound) examinations. The role of somatostatin receptor scintigraphy (SSR)b continued to be studied by the Rotterdam group. Forty previously untreated patients with histologically proven Hodgkins disease and 61 untreated patients with non-Hodgkins lymphoma were consecutively studied [6]. The results of the conventional staging methods were compared to Octreotide scintigraphy in 40 patients with proven Hodgkins disease. In 17 patients, Octreotide scintigraphy was in agreement, in 18 patients it was superior, and in five patients, it was inferior when compared to conventional staging methods. In seven patients, the clinical stage was altered because of Octreotide scintigraphy, raising it in six and lowering it in one. In the non-Hodgkins lymphoma group, 87 percent (53 of 61 patients) had positive scan findings, and in 31 patients, there was agreement. In 17 patients, additional lesions were revealed in Octreotide scintigraphy, which were not demonstrated by conventional staging methods. In five patients, lesions were missed. In 13 of the 61 patients, the Octreotide scintigraphy upgraded the stage of the disease. The group published some of their results of 56 consecutive untreated patients with histologically-proven Hodgkin's disease and compared the results of SSR with physical and radiological examinations as initial evaluation [8]. Somatostatin receptor scintigraphy was positive in 55/56 (95 percent) of patients at sites of documented disease. In 20 patients, SSR disclosed lymphoma localizations not