POSSIBILITIES AND LIMITATIONS OF RADIOIMMUNOSCINTIGRAPHY AND CONVENTIONAL DIAGNOSTIC MODALITIES IN CHOROIDAL MELANOMA

A prospective clinical study to assess the value of immunoscintigraphy with a monoclonal antibody (MoAb) against high molecular weight melan oma associated antigen (225.28S) was performed in 43 patients with cho roidal melanoma; in six patients with a lesion suspected of being chor oidal melanoma, and in seven patients with a benign lesion simulating a choroidal melanoma. The results of immunoscintigraphy in choroidal m elanoma were compared with results of conventional diagnostic modaliti es like ultrasonography and fluorescein angiography. Planar scintigrap hy showed a detection rate of 49% which is comparable with other studi es. The detection with scintigraphy was correlated to the size of the choroidal melanoma. The use of single photon computed tomography did n ot increase the sensitivity of immunoscintigraphy. Ultrasonography yie lded a correct diagnosis in 37 of 42 melanomas (88%). With fluorescein angiography a correct diagnosis was obtained in 11 of 30 melanomas (3 6.6%). The value of immunoscintigraphy with MoAb 225.28S in small chor oidal 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.