To investigate the spectrum of growth rates in melanomas and to identify clinical associations of rapidly growing melanomas.
Clinical interview, skin examination, and pathology review.
Three tertiary melanoma referral centers and 2 private dermatology practices.
A total of 404 consecutive patients with invasive primary cutaneous melanomas.
Main Outcome Measure
A surrogate for rate of growth in primary invasive melanoma was calculated as the ratio of Breslow thickness to time to melanoma development based on a previously reported assessment tool.
One third of the melanomas grew 0.5 mm per month or more. The median monthly growth rate was 0.12 mm for superficial spreading melanomas, 0.13 mm for lentigo maligna melanomas, and 0.49 mm for nodular melanomas. Rapid tumor growth was associated with tumor thickness (≤1 mm, geometric mean ratio [GMR] = 1.0; 1.01-4 mm, GMR = 3.9; and >4 mm, GMR = 12.1) and mitotic rate (<1/mm2, GMR = 1.0; 1-4/mm2, GMR = 2.9; 5-10/mm2, GMR = 6.1; and >10/mm2, GMR = 9.7). Rapid tumor growth occurred more often in males (GMR = 1.7), elderly individuals (≥70 years old, GMR = 2.8), and patients with fewer melanocytic nevi (n<50, GMR = 2.0) and fewer freckles (GMR = 2.5). Rapidly growing melanomas were more often symmetrical (GMR = 2.5), elevated (GMR = 1.4), amelanotic (GMR = 1.7), regular in border (GMR = 2.5), and symptomatic (GMR = 1.7).
Rapid growth of primary cutaneous melanomas is associated with aggressive histologic features and atypical clinical features. It occurs more frequently in elderly men and individuals with fewer nevi and fewer freckles.