Diagnosis and follow up of primary ocular melanoma by radioimmunoscintigraphy.
OBJECTIVE
To determine the usefulness of immunoscintigraphy with Tc-99m labeled anti-melanoma antibodies in the diagnosis of primary ocular melanoma. Furthermore, to try to determine whether the treatment of ocular melanoma by contact radiotherapy had an influence on the immunoscintigraphic disease detection.


METHODS
Immunoscintigraphy was performed on 17 patients: 9 patients with newly diagnosed choroidal melanoma (group A), 6 patients with choroidal melanoma treated by ruthenium contact radiotherapy (group B) and 2 patients with melanoma conjunctivae (group C). F(ab')2 fragments of 225.28S monoclonal antibody directed against a high molecular weight melanoma- associated antigen (HMW-MAA) were used. Planar scintigtaphy was done 4 hours after intravenous (i.v.) injection of 300-445 MBq of labeled antibodies, in anterior Waters projection, with 95 degrees of cranial tilt of the gamma-camera head. 500,000 counts static images were acquired in 256x256 resolution matrix.


RESULTS
All group A patients showed positive immunoscintigraphy. The maximum diameter of these tumors, measured by ultrasound, was between 9 and 18 mm, with maximal prominence between 5 and 10.5 mm. Both patients of group C showed negative immunoscintigraphy, due to the small dimensions of the tumors (less than 2.7 mm). In all 6 patients of group B immunoscintigraphy was negative although the dimensions of the tumors were sufficient enough to be visualized by immunoscintigraphy (diameter between 8.3 and 17 mm and prominence between 5 and 10.3 mm).


CONCLUSIONS
According to our preliminary results, we concluded that immunoscintigraphy was useful diagnostic modality in the detection of small intraocular tumors. The negative immunoscintigraphy in patients with tumors treated by contact radiotherapy could be explained by the biological regression of the tumor that precedes regression of its volume. This finding indicates that immunoscintigraphy could be useful in the follow-up of conservatively or surgically treated patients with choroidal melanoma.
Beatović
S
S
Institute of Nuclear Medicine, Clinical Center of Serbia, Beograd, Serbia and Montenegro.
Obradović
V
V
Latković
Z
Z
Jaksić
E
E