A 53-year-old woman was referred to a dermatologist because
of a verrucous nodule on the sole of her right foot (Panels A and B) that had
been treated as a plantar wart for 2 years by a podiatrist. A plantar wart was
diagnosed, and the patient underwent electrocoagulation therapy without histologic
examination. The lesion began to grow, and 6 months later, the patient came
to our clinic. Examination of her right foot revealed an erythematous, partially ulcerated,
nodular lesion, approximately 2 cm in diameter, covered by a thickened corneal
layer. Enlarged right inguinal lymph nodes were also identified. Histopathological
examination of the lesion showed an ulcerated, nodular, amelanotic malignant
melanoma, exceeding 6 mm in thickness (Clark’s level IV). The plantar melanoma
and involved inguinal nodes were excised, and interferon therapy was administered.
Plantar and subungual sites account for two thirds of melanomas of the foot and for
3 to 15% of all cutaneous melanomas. Acral melanomas may be misdiagnosed as
warts, calluses, fungal disorders, keratoacanthomas, nonhealing ulcers, foreign bodies,
moles, ingrown toenails, onychomycoses, and subungual hematomas. Six months
after coming to our clinic, the patient was found to have liver metastases, and she
died 6 months later.
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