Radioimmunoscintigraphy in Patients with Early Stage Cutaneous Malignant Melanoma

CT and MRI examinations remain relatively insensitive for the detection of metastatic melanoma lesions, especially those of regional lymph nodes. Imaging cutaneous malignant melanoma patients with the Fab fragment of monoclonal antibody (MAb) NR-ML-05 labeled with 99mTc has been reported to increase the accuracy of staging. Our purpose in this study was to assess the sensitivity of 99mTc-labeled NR-ML-05 in detecting the spread of melanoma. Twenty-six adult cutaneous malignant melanoma patients were enrolled in this study and were followed for 6 to 60 mo after radioimmunoscintigraphy. At the time of imaging, 20 patients had their primary lesions resected, whereas the remaining 6 patients had their primary lesions intact. Radioimmunoscintigraphy correctly detected 8 of 18 suspicious lesions as malignant, as well as 4 additional malignant lesions which had not been suspected previously. Radioimmunoscintigraphy also correctly identified 8 of the 18 suspicious lesions as benign. Two of the 18 suspicious lesions were found to be false negatives. The overall lesion sensitivity of radioimmunoscintigraphy was 86%. Twenty-four of the 26 patients were correctly staged by radioimmunoscintigraphy. The accuracy of staging of cutaneous malignant melanoma patients by clinical and or radiologic examinations (73%) was greatly improved with the use of radioimmunoscintigraphy (93%). These results suggest that radioimmunoscintigraphy may be a clinically useful adjunct to the current armamentarium for guidance of medical, and particularly surgical, therapy of cutaneous malignant melanoma patients.