Photo Rounds

Sore on arm

A 48-year-old man presented to his family physician (FP) with a 4-month history of a non-healing, crusty sore on his arm. The lesion presented without pigmentation. The patient admitted to having had a lot of sun exposure and did not use sunscreen.

What’s your diagnosis?


Sore on arm

The FP suspected that this was a skin cancer with ulceration rather than a dermatitis because of the ulceration and polymorphous vessels on dermoscopy. The differential diagnosis included squamous cell carcinoma, amelanotic melanoma, and basal cell carcinoma.

The FP explained to the patient that a biopsy would be needed and suggested a broad shave biopsy because it would provide adequate tissue to the pathologist. The physician performed a broad shave biopsy with a DermaBlade. (See the Watch & Learn video on “Shave biopsy.”) The biopsy report came back as amelanotic melanoma with a depth of 1.5 mm.

While most melanomas have visible pigment, some melanomas will present without pigmentation. Based on a Breslow depth of 1.5 mm, the patient was sent to Surgical Oncology for a wide excision with 1 cm margins and sentinel lymph node biopsy. Fortunately, the sentinel lymph node biopsy did not show any metastasis. The FP advised the patient that he would require regular skin surveillance and would need to take skin care precautions when exposed to the sun.

Photo courtesy of Jonathan Karnes, MD and text for Photo Rounds Friday courtesy of Richard P. Usatine, MD. This case was adapted from: Karnes J, Usatine R. Squamous cell carcinoma. In: Usatine R, Smith M, Mayeaux EJ, et al. Color Atlas and Synopsis of Family Medicine. 3rd ed. New York, NY: McGraw-Hill; 2019:1103-1111.

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