Immunoscintigraphy for ocular melanoma: a reliable diagnostic technique?

BACKGROUND: Immunoscintigraphy (IS) has recently been used as a diagnostic 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 tumour tissue. METHODS: During a 4-year period, IS was performed on 35 patients (average age 64 years) with suspected ocular melanoma by i.v. injection of 225.28S, a monoclonal antibody against high-molecular-weight melanoma-associated antigen. Histology was available in 22 cases. Tumour tissue was evaluated for cell type, vascularization, necrosis, pigmentation, and lymphocytic infiltration, and immunohistochemistry was performed with 225.28S and antibodies against HMB-45, S-100 and vimentin. One hundred and two patients with metastasizing cutaneous melanoma served as controls. In these patients the identical immunoscintigraphic technique was applied. RESULTS: IS yielded a positive result in about 50% of our patients with ocular melanoma, while in patients with cutaneous melanoma sensitivity was 89%. In five patients who turned out not to have melanoma, two false-positive results were obtained (one subretinal hemorrhage and one Wegener's granulomatosis). No correlation was found between any of the histological features or the immunoreactivity pattern and the immunoscintigraphic outcome. However, antigenic differences between ocular and cutaneous melanoma were evident. CONCLUSION: 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 characteristics or technical problems, are responsible for the low sensitivity in ocular melanoma compared to cutaneous melanoma.

[Antigen pattern in choroid melanoma in correlation with immunoscintigraphy]. / Antigenmuster beim Aderhautmelanom in Korrelation zur Immunszintigraphie.

We have reported that the sensitivity of immunoscintigraphy in ocular melanoma is fairly low in comparison with (metastasizing) cutaneous melanoma. No significant correlation was found between the histological data for ocular melanoma and the immunoscintigraphic results. We therefore wanted to see whether we could demonstrate an antigen pattern that was different from that of cutaneous melanoma, which might explain our previous results. Our study comprised tumor tissue from 20 patients with ocular melanoma who had undergone previous immunoscintigraphic examination. Using immunohistochemical techniques, tumor immunoreactivity was investigated against 225.28S, the antibody used for immunoscintigraphy, on cryosections in 12 cases, and against anti-HMB-45, and anti-S-100 and anti-vimentin on paraffin sections in all 20 patients. In summary, there was marked immunohistochemical heterogeneity, and none of the antibodies examined showed a significant correlation with immunoscintigraphy. Even 225.28S that was used for the immunoscintigraphic examination did not retrospectively allow a predictable immunoscintigraphic outcome. When comparing our results with the literature on cutaneous melanoma we were also able to confirm differences in immunoreactivity with regard to the other antibodies. We conclude that the comparatively poor results in ocular immunoscintigraphy obtained with 225.28S are due to antigenic differences between ocular and cutaneous melanoma.

[Immunoscintigraphy results in the comparison of ocular with cutaneous melanoma]. / Immunszintigraphische Ergebnisse beim okulären im Vergleich zum kutanen Melanom.

For several years, immunoscintigraphy (IS) using a 99mTc-labeled monoclonal antibody for tumor localization has been used as an additional tool in the diagnosis of malignant melanoma. The aim of our study was to verify previously published data with respect to our own patients and to correlate immunoscintigraphic results with histological findings. In particular, we wanted to compare the outcome of IS in ocular melanoma with that in cutaneous melanoma. We examined 28 patients (15 females, 13 males, average age 64 years) with clinically suspected ocular melanoma. IS was performed using the monoclonal antibody 225.28S (Tecnemab-K-1, Fa. Sorin/Solco), and images were obtained in a standard fashion (planar) as well as with the SPECT technique. In 16 patients, the tumor was examined afterwards histologically. The control group consisted of 102 patients with histologically proven metastasizing cutaneous melanoma who were investigated by IS in an identical fashion. In contrast to the literature published so far, we demonstrated a positive IS reaction in only 42% (and 56% in histologically proven cases, respectively) in our patients with ocular melanoma, while in patients with cutaneous melanoma, we found a sensitivity of more than 80%. In the 3 patients who turned out not to have ocular melanoma, we found one false-positive reaction (subretinal hemorrhage). No correlation was found between the various histological features of ocular melanoma and the immunoscintigraphic results. We conclude that IS using the antibody 25.28S is of limited value in patients with ocular melanoma and should only be recommended in selected cases.(ABSTRACT TRUNCATED AT 250 WORDS)