This hypermelanotic Clark nevus is characterized by a centrally situated diffuse regular pigmentation also called black lamella
The diffuse irregular pigmentation in the left lower part of this lesion facilitates the dermoscopic diagnosis of melanoma
The localized regular hyperpigmentation within this Clark nevus correlates to pigmented melanocytes/nevus cells within the papillary dermis. The significance of these eccentric foci of hyperpigmentation (“small dark dots”) within melanocytic nevi has been elaborated by Bolognia et al. [Arch Dermatol 1994]
The localized irregular pigmentation, formerly also called irregular extensions, is the dermoscopic hallmark of this malignant melanoma
The diffuse regular pigmentation present in the center of this hypermelanotic Clark nevus corresponds to numerous clumps of melanin throughout the thickened cornified layer. This rather distinctive histopathologic finding is also called pigmented parakeratosis (Cohen et al. Am J Dermatopathol 1997)
The diffuse irregular pigmentation that can be recognized dermoscopically in this melanoma correlates to the confluent, variously sized and shaped nests of heavily pigmented melanocytes at the dermo-epidermal junction and within the papillary dermis