MedWire News: The prevalence and type of acral melanocytic nevi in individuals seeing a dermatologist appear to be associated with ethnicity, pigmentation, age, gender, and risk factors for cutaneous melanoma, study results show.
Study authors Gary Palicka and Arthur Rhodes, from Rush University in Chicago, Illinois, USA, say that the findings may be "relevant to the predictive value of morphologic features used in the differential diagnosis of cutaneous melanoma."
The age-adjusted annual incidence rate of cutaneous melanoma in the USA is 1.1 and 25.3 per 100,000 population for Black and White individuals, respectively. This difference may relate to constitutive pigmentation and/or genetic factors associated with pigmentation and melanocytic neoplasms.
"There is a pressing need for clinical-histopathologic correlation studies of common acral nevi to determine the sensitivity and specificity of gross morphologic features in predicting histopathologic melanocytic dysplasia or acral cutaneous melanoma," the researchers comment in the Archives of Dermatology.
In the current study they assessed 513 adults (343 White, 119 Black, and 51 other ethnicities) who were visiting the outpatient dermatology service at Rush University Medical Center for routine care.
They determined the prevalence and morphologic features of unselected acral melanocytic nevi (those not selected for excision).
Palmar or plantar nevi were detected in 50 (42.0%) Black participants and 79 (23%) White participants, giving a significant difference.
Palmar or plantar nevi 6 mm diameter or larger were detected in four (3.4%) Black participants and two (0.6%) White participants, giving a difference of borderline significance.
Diffusely black acral nevi did not occur in any White individuals and in just one Black participant.
The prevalence of palmar or plantar nevi increased directly with the degree of constitutive skin pigmentation.
Among Whites participants, the occurrence of at least 1 palmar or plantar nevus was more common in women (27.1%) than in men (18.1%), and in individuals younger than 50 years (30.8%) than in those 50 years or older (13.9%.)
The presence of at least 1 palmar or plantar nevus was significantly associated with having any established cutaneous melanoma risk factor (odds ratio=2.2), including a history of atypical nevus removal, at least 1 extant atypical nevus, or at least 20 nevi of 2 mm diameter or larger.
There was insufficient data to assess these variables in Black participants.
The researchers comment: "We suggest that diameter alone may not be sufficient to require biopsy to exclude acral cutaneous melanoma or to obviate the need for biopsy for a clinically atypical or unstable lesion smaller than 7 mm in diameter.
"It is possible that there are unique varieties of acral nevi that represent risk factors and/or potential precursors of acral cutaneous melanoma."
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