Malignant melanoma: correlating abdominal and pelvic CT with clinical staging.

Two hundred two patients with malignant melanoma underwent computed tomography (CT) scanning of the abdomen and pelvis. The frequency of metastases in the abdomen and pelvis was correlated with the site, level, and thickness of the primary tumor. The sites of the primary tumors were the trunk (70 patients), the lower extremities (37 patients), the upper extremities (33 patients), the head and neck (29 patients), the eye (nine patients), and the genitourinary tract (six patients). In 18 patients, the primary site could not be identified. In 96 patients, the level and thickness of the primary tumor, based on Clark and Breslow classifications, were correlated with the presence and extent of metastases. CT showed metastases in 122 patients (60%). The head and neck were the most common primary sites associated with metastases (79%), followed by the eye (77%) and genitourinary tract (67%). Thick lesions had the highest frequency of metastases (84%), compared with intermediate (50%) and thin (46%) lesions. Tumors classified as Clark level V had the highest frequency of metastases (87%).