By Anne Harding
NEW YORK (Reuters Health) - New findings suggest that mechanical stress may promote melanoma formation on the plantar surface.
"We should suspect melanoma more strongly in a case of a developing pigmented lesion located on the plantar mechanical stressful areas, including the heel," Dr. Ryuhei Okuyama' of Shinshu University School of Medicine in Matsumoto, Japan, told Reuters Health by email. The findings were published online June 16 in the New England Journal of Medicine.
While sun exposure is the key risk factor for melanoma on the skin, the malignancy can also occur on non-sun-exposed parts of the body, such as the volar surfaces, Dr. Okuyama and colleagues state in their report. These melanomas usually do not have the oncogenic BRAF mutation seen often in melanomas on sun-exposed skin, they add.
In the new report, the researchers looked retrospectively at patients treated at their hospital for plantar surface melanomas between 1990 and 2014.
The average density of distribution for the entire plantar surface was 0.40 lesions/cm2. But lesions were distributed more densely in the rear (0.87/cm2) and front (0.71/cm2) of the feet, and less densely in the arch (0.07/cm2). There was no association between patterns of melanoma distribution and the lesions' Breslow thickness.
"Our results suggest that mechanical stress is an oncogenic stimulation for melanoma development in addition to ultraviolet irradiation," Dr. Okuyama told Reuters Health.
The incidence of cutaneous melanoma on the sole is 2.2 cases per million blacks and 2.4 cases per million whites in the United States, the researcher added.
"Melanoma on the sole is easily missed," he said. "Therefore it occasionally becomes advanced and incurable when diagnosed."
Dr. Okuyama said he and his colleagues are now investigating nail melanoma, which they expect is also due to mechanical stress.
The Japanese Society for the Promotion of Science supported this research. The authors made no other disclosures.
SOURCE: https://bit.ly/28UvHHI
N Eng J Med 2016.
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