Melanoma risk associated with solar elastosis.
The two retrospective studies considered me presence of dermal solar elastosis a surrogate marker for sun damage to skin, and found solar elastosis in 61% of 368 consecutive cases of cutaneous invasive melanoma, and in 77% of 380 consecutive cases of melanoma in situ diagnosed at the University of Texas Southwestern Medical Center at Dallas.
"There definitely is an association. That association needs to be investigated further," Dr. Crystal Thomas said at a poster presentation at the annual meeting of the American Society of Dermatopathology. She presented the melanoma in situ study, and Dr. Barry White presented a poster on the invasive melanoma data. Both investigators and their associates are with the University of Texas.
Several prominent dermatologists in recent years have argued that solar elastosis is coincidental with a melanoma diagnosis, not contributive, and is related only to patient age. Some have even argued that solar elastosis may be protective, with cutaneous melanomas occurring at older ages in people with solar elastosis (Am. J. Clin. Pathol. 2007;128:260-4).
In the patients with invasive melanoma, 59% of cases occurred in sun-exposed sites, and the presence of solar elastosis correlated significantly with greater depth of invasion, Dr. White reported. The presence of solar elastosis was associated with an average age of 66 years. The 39% of melanomas in patients without solar elastosis were more likely to occur in younger patients (average age, 47 years) and in body sites that were not considered exposed to the sun.
"We believe this indicates that a different pathogenic mechanism is at work in younger individuals with melanoma" and that sun exposure does contribute to melanoma risk in most patients, Dr. White concluded. More research is needed, however, to prove a causal relationship.
In the study of melanoma in situ, 38% of all patients showed moderate or severe solar elastosis within the papillary dermis, and 39% had mild solar elastosis.
Sun-exposed body sites accounted for 62% of locations of melanoma in situ, Dr. Thomas reported. The most common locations for melanoma in situ were the face, back, and arms. The most frequent sites for solar elastotic changes were the face, scalp, ears, arms, hands, and shoulders. Least likely to have solar elastosis were the buttocks, nails, feet, and legs.
Although the studies do not show that sun exposure causes melanoma, the association is strong enough for physicians to take heed, she said. "It is important to tell your patients to wear sun block and protect their skin from the sun," Dr. Thomas said.
The likelihood of solar elastosis increased with age; signs began to appear between ages 30 and 39 years, and to present in a majority of patients by age 40 years. None of seven patients with melanoma in situ before age 30 had evidence of solar elastosis.
Melanoma in situ in sun-exposed areas was more common in older than in younger patients, and the reverse was true for melanoma in situ in body areas not exposed to the sun, which was more common in younger patients.
The presence of dysplastic nevi in association with melanoma in situ was more common in younger patients than older ones, with a peak incidence in 30-to 39-year-olds and a decline after age 60.
Previous studies have shown that ultraviolet radiation damages DNA and can result in the development of various cutaneous tumors. Melanomas have been induced in animal studies after exposure to intense ultraviolet light, or to a chemical carcinogen followed by ultraviolet light.
BY SHERRY BOSCHERT
San Francisco Bureau
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|Publication:||Internal Medicine News|
|Date:||Dec 1, 2008|
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