Malignant melanoma originating from intradermal nevi. A clinicopathologic entity

Abstract

Two cases of malignant melanoma arising in preexisting intradermal nevi without a junctional element are described. These cases and the two known to have been reported previously demonstrate similar clinical and morphologic findings. These include an innocuous gross appearance, a nodular growth pattern, and deep levels of invasion. It appears that the origin of the tumor in the dermis conceals malignant transformation. The consequent time lapse and the dermal position of the lesion favor deep penetration of the tumor prior to removal.

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

“…In contrast to our lesion, their lesion was composed of an intradermal nevus in the upper portion of the dermis, and a deeper nodule composed of malignant neoplastic cells that extended into the reticular dermis, and only these deeper cells were positive for HMB45 while upper ones were not [21]. In another report, Benisch et al reported two NM lesions originating from intradermal nevi [22]. Our lesion was a SSM.…”

Macular-appearing Nodular melanoma Arising from a Preexisting Melanocytic nevus in an Elderly patient--Can “Older Age of Nevus” be Besponsible for Unusual Morphogenesis and Melanomagenesis?

“…In another report, Benisch et al reported two NM lesions originating from intradermal nevi (24). Similar to the Tsao et al's suggestions, these authors speculated that, the reason for this nonhierarghical MM development from an intradermal nevus could be related to advanced age of patients (14,23,24). Our lesion arose from an acquired common melanocytic nevus existing for many years.…”

Malignant Melanoma Developing from an Intradermal Nevus

“…This may be specific in cases with malignant melanoma from an intradermal nevus, but the reason remains unclear. In 3 of the 4 previous reports, malignant melanomas developed beneath nests of nevus cells [1, 2, 3], while in the fourth report, it was shown that nevus cells were scattered throughout the nodule and blended with melanoma cells [5]. In the present case, melanoma developed upward from the nest of the intradermal nevus, and no junctional activity was seen.…”

“…In the cases reported, the melanoma cells were usually located beneath the intradermal nevus cells [1, 2, 3]. However, in the case described here, melanoma cells were located above the intradermal nevus without showing junctional activity, and a transitional zone was detected between nevus and melanoma cells.…”

“…We therefore considered this intradermal nevus to be acquired naturally [6]. In general, malignant melanomas accompany lymphocytic infiltration, but in the reported cases, lymphocytic infiltration was sparse [1, 2, 3]. The specimen of our patient also showed such a sparse lymphocytic infiltration.…”