Harrison's PodClass: Internal Medicine Cases and Board Prep Ep 127: A 65-Year-Old Male with a Spot on His Foot
Jan 2, 2025
A 65-year-old Black man develops a new pigmented lesion on the sole of his foot. The discussion works through why infection, diabetic ulcer, syphilis, and benign nevi are unlikely. Melanoma subtypes are compared, emphasizing acral lentiginous melanoma on palms and soles. The recommended next step is excisional biopsy for histologic assessment and staging if malignant.
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Don't Mistake Plantar Pigmented Lesions For Diabetic Ulcers
- Avoid assuming a diabetic foot ulcer for solitary non-tender plantar pigmented lesions without neuropathy or typical ulcer features.
- Consider melanoma when the lesion is pigmented, non-tender, and increasing in size despite diabetes history.
Rapid Growth Suggests Malignancy Not Dysplastic Nevus
- Do not assume dysplastic nevi when a lesion grows rapidly; dysplastic nevi usually do not enlarge over months.
- Use growth over weeks to months as a red flag favoring malignancy rather than benign atypical nevi.
Secondary Syphilis Usually Produces Widespread Lesions
- Secondary syphilis can involve the palms and soles but usually causes widespread lesions, not an isolated solitary lesion.
- A solitary dark macule on the sole is therefore unlikely to represent syphilis.
