A 61-year-old obese, man with type 2 diabetes presented with the gradual onset of a mildly tender lesion on the dorsum of the right arm. He had a well-known history of actinic keratoses and multiple nonmelanoma skin cancers.
Key point: The irregularly shaped lesion is erythematous and hyperkeratotic (Figures A and B), suggesting either an in situ or early invasive squamous cell carcinoma. However, a deep saucer-shaped shave biopsy only revealed a benign, irritated and inflamed seborrheic keratosis.
Treatment: In effect, the biopsy served as definitive treatment; no additional therapy was given.
Note: This case highlights how closely benign and malignant skin lesions can mimic one another. Obtaining histologic results from a representative biopsy is always a good idea before embarking on extensive therapy.