Melanoma(s) Associated with a Quadrant or Segmental Distribution of Atypical Melanocytic Nevi

Abstract

The authors have indicated no significant interest with commercial supporters.A cquired melanocytic nevi, particularly if multiple and uneven in their clinical features (also called atypical melanocytic nevi, Clark's nevi, or dysplastic nevi), are considered to represent indicators for risk of melanoma development. 1 Such nevi typically develop at puberty and appear in most occasions to be randomly distributed on the trunk. Agminated, unilateral, quadrant, or segmental distribution of different types of melanocytic skin lesions have been described, 2-5 being associated with a certain risk of melanoma development. [6][7][8][9][10] We report a 30-year-old woman who developed two primary melanomas on her left lower extremity where numerous atypical melanocytic skin lesions were seen in a quadrant or segmental distribution. Case ReportA 30-year-old woman presented at our specialized pigmented lesion clinic for a routine check of her nevi. Her medical history revealed a polypoid spitzoid melanoma (Clark level IV, tumor thickness 2.4 mm, negative sentinel node) excised at another institution 4 years before on her left hip. There was no family history of melanoma or familial atypical nevus syndrome.Clinical examination revealed, in addition to a few scattered small nevi on the trunk, a cluster of approximately 70 aggregated melanocytic skin lesions on the distal ventral half of her left thigh ( Figure 1) and approximately 20 additional lesions loosely distributed on the rest of the leg, including the area of the previous melanoma. Examination with Wood's light revealed no background pigmentation suggestive of speckled nevus. The patient reported the onset of the lesions after the age of 15 and denied a history of sunburns confined to this area.Dermoscopically, most lesions revealed benign features, but a few within the cluster exhibited slightly atypical structures, such as prominent network, irregular dots or globules, and grayish pigmentation. 11 None of the lesions revealed features suggestive of melanoma. Digital dermoscopy imaging of the slight atypical lesions was thus performed, and the patient was scheduled for short-term monitoring. 12 After 4 months, side-by-side comparison with the baseline images revealed no significant changes. Only one lesion within the cluster showed symmetric enlarge-

Melanocytic naevi clustered on normal background skin

“…1g). In seven instances, a high number of other melanocytic naevi were also present and arranged in a nonsegmental fashion, [24][25][26] and in four cases, they developed into MM. [25][26][27] Segmentally arranged DMN probably represent a mosaic form of dysplastic naevus syndrome (DNS).…”

“…In seven instances, a high number of other melanocytic naevi were also present and arranged in a nonsegmental fashion, [24][25][26] and in four cases, they developed into MM. [25][26][27] Segmentally arranged DMN probably represent a mosaic form of dysplastic naevus syndrome (DNS). As DNS appears to be a polygenic trait, DMN confined to a cutaneous segment should be defined as 'isolated segmental DNS', 28 while segmentally arranged DMN cooccurring with widespread, nonsegmental DMN [24][25][26] configures a 'superimposed segmental DNS' according to a recent paradigm for mosaic polygenic disorders.…”

“…g). In seven instances, a high number of other melanocytic naevi were also present and arranged in a nonsegmental fashion, and in four cases, they developed into MM …”

“…[25][26][27] Segmentally arranged DMN probably represent a mosaic form of dysplastic naevus syndrome (DNS). As DNS appears to be a polygenic trait, DMN confined to a cutaneous segment should be defined as 'isolated segmental DNS', 28 while segmentally arranged DMN cooccurring with widespread, nonsegmental DMN [24][25][26] configures a 'superimposed segmental DNS' according to a recent paradigm for mosaic polygenic disorders. 29 Similarly to most such disorders, mosaicism has not yet been proved at the molecular level for DNS.…”