[516] Acral Nevi as Possible Precursors to Acral Melanomas?

Jonathan Lai, Cynthia M Magro. University of Toronto, Toronto, ON, Canada; Weill Cornell Medical College, New York, NY

Background: Melanocytic nevi with site-related atypia display inherent architectural disorder and cytologic abnormalities that can mimic dysplastic nevi or melanoma. Under this category, these nevi include melanocytic proliferations from acral, genital, special site (breast, flexural, scalp and auricular), and conjunctival areas on the body. To date, it is general accepted that that nevi with site-related atypia are biologically stable and do not possess an increased risk of malignant transformation. However, it has been the experience of one of the authors (CMM) that acral melanoma can arise in the background of an acral nevi precursor lesion.
Design: To investigate this further, a natural language search within the division of dermatopathology case database at Weill Cornell Medical College was conducted from 2006 to 2011 to identify cases of acral melanoma. Melanomas occurring on the ankle, foot, hand, and nail apparatus were considered of true acral origin. Reports of cases of acral melanoma were reviewed to see if a precursor lesion was present.
Results: Our search yielded a total of 48 acral melanomas, of which 39 (81%) were of acral lentiginous type, 8 (17%) were of superficial spreading type, and 1 (2%) was of nodular type. Of the 48 patients, 32 were female and 16 were male. The age ranged from 30 years to 98 years, with an average age of 62. Within the acral lentiginous melanomas and superficial spreading melanomas, 10 of 41 (24%) and 5 of 9 (56%) arose from a precursor acral nevus respectively. These acral melanomas with precursor acral nevi all occurred on the foot with 6 of 15 lesions occurring on the plantar aspect, 8 of 15 lesions occurring on the dorsal aspect, and 1 case with an unspecified biopsy site. Interestingly, 6 of 48 (12%) acral melanomas arose from either nail matrix or nail bed; all of which did not show any evidence of a precursor lesion.
Conclusions: Our results challenge the commonly held viewpoint that acral melanomas rarely arise from a precursor lesion and more often arise de novo. We acknowledge that this may indeed be the case for acral melanomas of the nail matrix and nail bed. However, a diagnosis of acral nevus may in fact require closer clinical follow-up and more aggressive management. Further investigation into the molecular alterations of acral nevi are needed to correlate with known molecular alterations in acral melanomas such as mutations in the receptor tyrosine kinase KIT or cyclin D1 gene amplifications.
Category: Dermatopathology

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 112, Wednesday Afternoon

 

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