SAN DIEGO — Melanoma of the foot and ankle occurred far more commonly in women than it did in men, but men were more likely to have thicker tumors that were associated with a worse prognosis, Dr. Hugh T. Greenway said at the annual meeting of the California Society of Dermatology and Dermatologic Surgery.
In a review of 63 cases seen over 20 years at the Scripps Clinic in La Jolla, Calif., patients were the first to draw attention to melanoma lesions in 44 cases. Physicians spotted them in seven cases, and both were credited in five, Dr. Greenway reported.
There was no association between trauma and melanoma in the series.
Possible factors contributing to the disease remain unclear, said Dr. Greenway, who heads the clinic's division of Mohs/dermatologic surgery.
Sunburns, the binding pressure of shoes, and perhaps exposure to unfiltered radiation from fitting devices at Buster Brown shoe stores in the 1950s and 1960s may be contributing to melanoma of the lower extremities.
In all, foot and ankle melanoma constituted 4% of all melanoma cases diagnosed at Scripps over 2 decades, occurring in 47 women and 16 men. The mean age at diagnosis was 58 years.
Melanomas occurring on the foot and ankle are more often misdiagnosed than melanomas on any other anatomic site, Dr. Greenway said. In his series, 10 cases, or 16%, were originally misdiagnosed.
“We're used to seeing benign conditions of the foot,” he said, noting that some melanoma lesions may be dismissed as verrucae, toenail onychomycosis, subungual hematomas, tinea pedis, or ischemic ulcers.
“For the most part, prognosis is not good,” with 5-year survival ranging from 52% to 71% in previous series, noted Dr. Greenway.
The Scripps series showed a 4-year survival of 80%, with disease-free survival in 73% (46 patients). One reason for the high survival of Scripps patients could be that 24 of the 63 cases were melanoma in situ.
“The real key [to generally poor survival statistics] is that we don't pick these up as early as we do melanoma on other parts of the skin surface,” he said.
People don't regularly examine their feet, and the process becomes even more difficult with age and infirmities. In addition, some clinicians don't even have patients remove their socks during skin examinations, said Dr. Greenway.
Women may be diagnosed with less-thick melanomas because they pay more attention to their feet than men do and they are also more likely to get pedicures, he speculated.
Presumably these cases are diagnosed earlier.
Many patients, however, have trouble remembering how long the lesions have been on their feet or ankles, perhaps accounting for the failure of Dr. Greenway's group to find an association between tumor thickness and duration.
In 10 cases, a biopsy underestimated the Breslow thickness of the tumor. Seven of these cases were upstaged during the treatment process, which consists of surgery, consideration of sentinel node examination, a metastatic and oncology evaluation, and follow-up.
Disease-free survival was significantly worse in the Scripps series for thicker tumors, a higher stage, males, and tumors initially misdiagnosed.
Increased surveillance did not improve survival in the series, he noted.
ELSEVIER GLOBAL MEDICAL NEWS