Acral Plantar Melanoma Mimicking a Diabetic Foot Ulcer in a Nonagenarian: A Case Report.

Acral melanoma on the plantar surface may be clinically overlooked and can resemble common causes of plantar ulceration. In patients with diabetes, chronic plantar lesions are often managed as diabetic foot ulcers, which can delay consideration of alternative diagnoses. We report the case of a very elderly woman with diabetes whose plantar lesion was initially treated as a diabetic foot ulcer but later evolved with features concerning for malignancy. Histopathology confirmed deeply invasive ulcerated acral melanoma. This case highlights the importance of maintaining suspicion for malignant mimics in non-healing plantar lesions and supports early biopsy when a presumed diabetic foot ulcer behaves atypically or fails to improve with appropriate care.