Regression of malignant melanoma is a complex interaction between host and tumor. The end result, when successful from the host's point of view, is complete destruction of tumor cells, leaving only scar. Clinically, regression usually shows irregular loss of pigment, with a macular gray or blue-gray zone. Histologically, regression can be recognized in its early stages by the cellular inflammatory host response seen in the radial growth phase of superficial spreading malignant melanomas. Later end-stage regression is characterized by fibrosis and residual inflammatory cells with incontinence of pigment. The complexity of regression is illustrated by the fact that some patients have malignant melanoma that remains in the radial growth phase for several years without apparent clinical or histologic end-stage regression, while others may have both clinical and histologic evidence of regression relatively early in the evolution of the disease.
Does regression have clinical usefulness as a marker for the potential
Sagebiel R. Regression and Other Factors of Prognostic Interest in Malignant Melanoma. Arch Dermatol. 1985;121(9):1125-1126. doi:10.1001/archderm.1985.01660090039009