MALIGNANT-MELANOMA OF THE FOOT AND ANKLE

The records of sixty patients who had a malignant melanoma of the foot or ankle were reviewed retrospectively to determine the clinical feat ures, prognostic factors, and distinguishing characteristics. Fifty-se ven patients were white and three were black. There were forty-two wom en and eighteen men (a female-to-male ratio of 2.3 to 1). The mean age at the time of presentation was fifty-seven Sears (range, twenty-two to eighty-three years). The most common site of involvement was the pl antar aspect of the foot. The mean duration of follow-up was forty-fiv e months (range, three to 144 months). Kaplan-Meier life-table analysi s revealed an overall five-year survival rate of 63 per cent and an ov er-all ten-year survival rate of 51 per cent. The mean duration of sur vival for the patients who had a plantar or subungual lesion was signi ficantly shorter than that for the patients who had a lesion at anothe r site on the dorsal aspect of the foot or on the ankle (forty-seven c ompared with seventy-two months) (p = 0.02). The mean depth of the les ion, according to the criteria of Breslow, was 3.03 millimeters, and t he mean level, according to the classification of Clark et al., was IV . According to the classification of the American Joint Commission on Cancer, forty-three patients had stage-I or II (local) disease, thirte en had stage-III disease (nodal or in-transit disease, defined as cuta neous or subcutaneous metastases more than two centimeters from the pr imary tumor but not beyond the regional lymph nodes), and four had sta ge-IV disease (distant visceral metastases) at the time of presentatio n. Lesions at plantar and subungual sites were also associated with a higher prevalence of clinical misdiagnosis compared with lesions on th e dorsal aspect of the foot or on the ankle (p = 0.02). The misdiagnos es included a benign nevus (one patient), a paronychia (one patient), a pyogenic granuloma (two patients), a plantar wart (three patients), a ganglion cyst (one patient), a blister (two patients), and a traumat ic lesion (five patients). The fifteen patients in whom the lesion had initially been misdiagnosed had a mean duration of survival of twenty -two months, compared with sixty-seven months for the forty-five patie nts in whom the melanoma had initially been diagnosed misdiagnosed had a greater mean depth than those that had been diagnosed correctly (4. 31 compared with 2.62 millimeters; p = 0.4) at the time that the patie nts were first seen at our institution. The poorer survival rate for o ur patients, who had a melanoma of the foot or ankle, compared with th e previously reported survival rates for patients who had a melanoma i n other parts of the body, reflects the advanced stage of the disease and the greater depth of these lesions at the time of the diagnosis. T hese two factors may also be related to a delay in the correct diagnos is.