That's the conclusion drawn from a study by researchers affiliated with University of Iowa Hospitals and Clinics. The study found an inverse relationship between a man's density of body hair growth and the number of pigmented lesions that may progress into malignant melanoma, or skin cancer.

Published in Melanoma Research, the findings confirm the researchers' hypothesis that, in the absence of normal body hair growth, melanocytes (cells that produce melanin, a dark pigment) in hair follicles might develop into pigmented lesions.

Pigmented lesions were classified as a darkly pigmented spot at least three millimeters in diameter.

"The study reflects the hypothesis that some pigmented lesions may arise from the melanocytes of the hair follicles rather than just the melanocytes in the skin," said Joanne Tobacman, M.D., assistant professor of internal medicine. "The research may help us think about new ways of treating malignant melanomas."

If the coordinated growth of the follicular cells (keratinocytes and melanocytes) is disrupted and hair growth fails, the pigment that would normally color the growing hair instead may accumulate as a pigmented lesion, Tobacman said.

In addition to Tobacman, who led the study, co-investigators included Duane Whitaker, M.D., professor of dermatology, and Bridget Zimmerman, Ph.D., director of the UI Biostatistics Consulting Center.