Computed tomography of cranial metastatic malignant melanoma: features, early detection and unusual cases.

The cranial computed tomographic (CT) scans reported as showing metastatic disease in patients with malignant melanoma (MM) seen at the Westminster Hospital over a 5 year period were reviewed. Ninety-eight patients with intracranial metastatic MM were identified. Twelve had an initial scan which was reported as normal and particular attention was given to these to see if, in retrospect, any early features of metastatic disease were discernible. Fifty-eight cases showed the "typical" features of intracranial MM; the remainder were unusual in appearance, behavior, or site. Radiological regression was shown in only seven cases on follow-up scans; all but one of these patients had one or two large metastases. No significant lesion was thought to have been missed on a scan after the administration of intravenous contrast medium, but the lesions of three patients were difficult to discern on plain scans. Thus when MM metastasis is suspected, the use of the contrast-only scan is advocated.