Radiation-induced malignant melanoma: the dog that did not bark.

A history of exposure to ultraviolet rays, such as those in sunlight, has been strongly associated with malignant melanoma. Gamma rays consist of much more energetic photons, but yet they have much more tenuous links to melanoma. A literature review suggests that relatively little evidence has been adduced for gamma radiation as a cause of malignant melanoma. An exploration of the reasons behind the paradoxical lack of melanoma induction by gamma radiation may yield clues to the etiology of melanoma.