Survival for 38 years with Animal-type malignant melanoma

A 38-year-old female came with a dark pigmented nodular lesion on the left labium majus which was present since birth. Grossly, the lesion was uniformly black in colour<br>and measured 7x4.5x3 cm. Cut-sections showed dark pigmentation up to the level of subcutaneous fat. Microscopically, there was assymetrical proliferation of mildly atypical, polygonal tumor cells having moderate amount of heavily melanized cytoplasm in the dermis and subcutis (Clark level V). Maturation with descent was not present. Breslow thickness was 11mm. Invasion of hair follicles and subcutaneous fat was present. Intra and perineural invasion were also seen. Nucleoli were small. Animal-type malignant melanoma was the diagnosis. The patient was alive and otherwise healthy for 38 years because the tumor is low-grade malignant.