A prospective clinical study to assess the value of immunoscintigraphy with a
monoclonal antibody (MoAb) against
high molecular weight melanoma associated antigen (225.28S) was performed in 43 patients with choroidal
melanoma; in six patients with a lesion suspected of being choroidal
melanoma, and in seven patients with a benign lesion simulating a choroidal
melanoma. The results of immunoscintigraphy in choroidal
melanoma were compared with results of conventional diagnostic modalities like ultrasonography and
fluorescein angiography. Planar scintigraphy showed a detection rate of 49% which is comparable with other studies. The detection with scintigraphy was correlated to the size of the choroidal
melanoma. The use of single photon computed tomography did not increase the sensitivity of immunoscintigraphy. Ultrasonography yielded a correct diagnosis in 37 of 42
melanomas (88%). With
fluorescein angiography a correct diagnosis was obtained in 11 of 30
melanomas (36.6%). The value of immunoscintigraphy with MoAb 225.28S in small choroidal
melanomas is limited; its reliability increases in large tumours. Immunohistochemistry with MoAb 225.28S showed
antigen expression in 95% of the stained tissue specimens of choroidal
melanoma.