Acral melanoma in Japan.

Area of Science:

• Dermatology
• Oncology
• Pathology

Background:

• Malignant melanoma incidence and mortality rates have been rising globally.
• Acral melanomas, particularly on plantar surfaces, present unique diagnostic and therapeutic challenges.
• Understanding the epidemiology and clinicopathologic features of melanoma in specific populations is crucial for public health.

Purpose of the Study:

• To analyze the clinical and histologic characteristics of malignant melanoma in Japanese patients.
• To assess trends in malignant melanoma mortality and survival rates in Japan.
• To compare the features of acral melanomas in Japan with those reported internationally.

Main Methods:

• Retrospective review of clinical records and histologic materials from 81 malignant melanoma patients at Tohoku University School of Medicine.
• Statistical analysis of 1597 malignant melanoma cases from Japanese literature (1961-1982).
• Detailed clinicopathologic examination of acral melanoma cases.

Main Results:

• The annual mortality rate for malignant melanoma in Japan showed a near-linear increase over 20 years, reaching 0.21 per 100,000 in 1980.
• The five-year survival rate at Tohoku University was 35%.
• Acral sites, especially plantar surfaces, were the most common locations for melanoma. Clinicopathologic features of these acral melanomas were consistent with acral lentiginous melanoma observed in the United States.

Conclusions:

• Malignant melanoma represents a growing public health concern in Japan, with increasing mortality rates.
• Acral lentiginous melanoma is a significant subtype, sharing similar clinicopathologic features across different geographic regions.
• Further research and improved early detection strategies are warranted to improve survival rates for malignant melanoma.