IMMUNOSCINTIGRAPHY FOR OCULAR MELANOMA - A RELIABLE DIAGNOSTIC-TECHNIQUE

Background: Immunoscintigraphy (IS) has recently been used as a diagno stic tool for ocular melanoma. We wanted to reevaluate published data in our own patients and to correlate immunoscintigraphic results with histologic findings and immunohistochemical characteristics of the tum our tissue. Methods: During a 4-year period, IS was performed on 35 pa tients (average age 64 years) with suspected ocular melanoma by i.v. i njection of 225.28S, a monoclonal antibody against high-molecular-weig ht melanoma-associated antigen, Histology was available in 22 cases. T umour tissue was evaluated for cell type, vascularization, necrosis, p igmentation, and lymphocytic infiltration, and immunohistochemistry wa s performed with 225.28S and antibodies against HMB-45, S-100 and vime ntin. One hundred and two patients with metastasizing cutaneous melano ma served as controls. In these patients the identical immunoscintigra phic technique was applied. Results: IS yielded a positive result in a bout 50% of our patients with ocular melanoma, while in patients with cutaneous melanoma sensitivity was 89%. In five patients who turned ou t not to have melanoma, two false-positive results were obtained (one subretinal hemorrhage and one Wegener's granulomatosis). No correlatio n was found between any of the histological features or the immunoreac tivity pattern and the immunoscintigraphic outcome. However, antigenic differences between ocular and cutaneous melanoma were evident. Concl usion: We conclude that IS, using the antibody applied in this study, is of only limited value in patients with ocular melanoma. Our results suggest that antigenic differences, rather than histological characte ristics or technical problems, are responsible for the low sensitivity in ocular melanoma compared to cutaneous melanoma.