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acral Spitz nevi

Monday 30 April 2018

Spitz nevi on acral sites are rare and poorly documented. The combination of Spitzoid cytomorphology and atypical architectural features of the junctional component may lead to an erroneous diagnosis of melanoma.

Acral Spitz nevi is characterized by strong and diffuse P16 and P21 expression, which differs from acral nevi and acral lentiginous melanoma.

Acral Spitz nevi are a distinctive subgroup of Spitz nevi with benign behavior.

Awareness of the subtle histologic differentiating features and the distinctive P16/P21 expression pattern allows separation from melanoma.

Differential diagnosis

Acral nevi occasionally demonstrate pagetoid spread of melanocytes. This feature may be of considerable concern because it is commonly associated with melanoma.

Other features of melanoma must be assessed to accurately classify these neoplasms as benign.

The presence of pagetoid spread of melanocytes is common in otherwise benign acral nevi. Other parameters of malignancy in these neoplasms must be evaluated to determine their biologic potential.

Paywall references

- Acral Spitz Nevi: A Clinicopathologic Study of 50 Cases With Immunohistochemical Analysis of P16 and P21 Expression. Wiedemeyer K, Guadagno A, Davey J, Brenn T. Am J Surg Pathol. 2018 Mar 13. doi : 10.1097/PAS.0000000000001051 PMID: 29537991

- Acral melanocytic neoplasms: a histologic analysis of 158 lesions. Boyd AS, Rapini RP. J Am Acad Dermatol. 1994 Nov;31(5 Pt 1):740-5. PMID: 7929919