Nodular Melanoma-Like Superficial Spreading Melanoma Arising from Intradermal Unna Nevus-Can Incomplete Oncogenic-senescence be Responsible for Non-hierarchical Melanomagenesis?

Abstract

We report a 70-year-old woman who presented a superficial spreading malignant melanoma with a nodular melanoma appearance, located on her leg. Most common clinicopathological types of malignant melanoma are lentigo maligna, superficial spreading, nodular, and acral lentiginous melanoma. Unusual variants of melanoma are rare but important. These are amelanotic melanoma, neurotropic melanoma, desmoplastic melanoma, metastatic melanoma, invisible melanoma, balloon cell melanoma, melanoma arising within a benign nevus and pedunculated melanoma. The lesion of our patient simulated a nodular or a pedunculated melanoma clinically, but its histopathological examination showed a superficial spreading melanoma arising from the surface of an Unna nevus. To the best of our knowledge, such misleading nodular appearance of a superficial melanoma arising from an intradermal nevus of Unna which seems to be a unique finding has not been reported previously.