VERY LATE METASTASIS (27 YEARS) OF CUTANEOUS MALIGNANT-MELANOMA ARISING IN A HALO GIANT CONGENITAL NEVUS

We report a case of primary cutaneous melanoma with the incidental fin ding of a lung metastasis 27 years following the original diagnosis. T he case is exceptional in that it is a late metastasis of a melanoma t hat arose in association with a halo giant congenital nevus. The origi nal tumor was a large dermal/subcutaneous nodule composed of very well -differentiated cells reminiscent of type B nevomelanocytes. The metas tasis displayed similar histology. This case emphasizes the unpredicta ble behavior of malignant melanoma. In cases with 'unusual' histology such as this one, the usual prognostic parameters are less helpful in predicting survival. Melanoma should be included in the differential d iagnosis of an undiagnosed lesion suspicious for metastasis even if th e primary was removed in the remote past.