Nevus-associated melanomas: clinicopathologic features

Area of Science:

• Dermatology
• Oncology
• Pathology

Background:

• The clinical significance of nevus-associated melanoma versus de novo melanoma is debated.
• Previous suggestions indicated nevus-associated melanomas might have greater Breslow thickness and poorer prognosis.

Purpose of the Study:

• To evaluate the incidence of nevus-associated melanoma over a decade.
• To determine the prognostic significance of nevus-associated melanoma concerning clinicopathologic features.

Main Methods:

• A 10-year cross-sectional study (1995-2004) at a dermatopathology referral center.
• Analysis of 1,190 melanoma records from 135,653 skin biopsy specimens.
• Evaluation of clinicopathologic features including sex, location, subtype, Breslow thickness, Clark level, ulceration, and nevus association.

Main Results:

• Nevus-associated melanomas accounted for 32.8% (390 cases) of all melanomas.
• Thin melanomas showed a 1.52 times higher association with nevi compared to thick melanomas (P < .001).
• The median Breslow thickness was lower in nevus-associated melanomas than in de novo melanomas.

Conclusions:

• Nevus-associated melanomas constitute a significant proportion (one-third) of melanomas in southeast Brazil.
• These melanomas are associated with intermittent sun exposure, superficial spreading subtype, and thinner Breslow thickness.
• This study represents one of the largest series on nevus-associated melanomas in Latin America.