Rate of growth in melanomas: characteristics and associations of rapidly growing melanomas.

OBJECTIVES To investigate the spectrum of growth rates in melanomas and to identify clinical associations of rapidly growing melanomas. DESIGN Clinical interview, skin examination, and pathology review. SETTING Three tertiary melanoma referral centers and 2 private dermatology practices. PATIENTS 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. RESULTS 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 (4 mm, GMR = 12.1) and mitotic rate (<1/mm(2), GMR = 1.0; 1-4/mm(2), GMR = 2.9; 5-10/mm(2), GMR = 6.1; and >10/mm(2), GMR = 9.7). Rapid tumor growth occurred more often in males (GMR = 1.7), elderly individuals (>or=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). CONCLUSIONS 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.