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55-Year-Old Male with Asymptomatic Lesion on Back

Can you diagnose this case?

David L. Kaplan 2014 Series Editor @ University of Missouri – Kansas City School of Medicine

Signs and Symptoms

A 55-year-old male presented for his annual skin examination, which revealed an asymptomatic lesion on his back. It is of unknown duration as the patient was unaware of it. He had recently returned from extended travel overseas in Asia. He is otherwise healthy.

How would you diagnose his mystery lesion?

Choose one to reveal diagnosis and discussion

Insect bite reaction
Nummular eczema
Basal cell carcinoma
Amelanotic melanoma
Lichenoid keratosis

Answer: Amelanotic melanoma

See the full case at Consultant360

A biopsy showed this to be a 0.4 mm amelanotic melanoma. Amelanotic melanoma is an extremely difficult clinical diagnosis to make as demonstrated by this case. All of the differential diagnoses are reasonable, which made biopsy necessary to confirm the clinical diagnosis (not suspected prior to the biopsy). This also supports the importance of yearly physical examinations, action that was recently—and questionably—criticized by an academic physician in these 2 New York Times columns: “Skip Your Annual Physical” (Emanuel, EJ, Op-Ed, January 9, 2015) and “Your Annual Checkup” (Letters to the Editor, January 17, 2015).