Metastatic melanoma of unknown origin at autopsy

In 93 patients dying from metastatic melanoma the primary tumor was unknown in 13 (14%) after autopsy. There were no significant differences compared to cutaneous melanoma with respect to sex, age, organ distribution of metastases or final tumor load. An unknown primary was, however, significantly more common in cases presenting with general metastases compared to regional spread. The causes of death were similar to cutaneous cases. Our data suggest that melanoma of unknown origin has the same predilection and biology as metastatic cutaneous melanoma, supporting the view that regression of a cutaneous primary may be involved.