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Velvety brown lesion

A physician performing an annual skin check-up on a 56-year-old man with a history of melanoma and nonmelanoma skin cancer noticed a velvety brown skin lesion on the patient’s leg. The patient said he’d noticed the asymptomatic lesion a few months before the office visit. The physician noted a 1-cm, slightly raised tan lesion with a rice paper/wrinkly surface.

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Velvety brown lesion

Dermoscopy revealed a uniform, sharply demarcated, slightly scaly lesion on a background of occasional scale and solar-damaged skin. This appearance, paired with the absence of abnormal blood vessels or suspicious, irregular pigmentation, pointed to a diagnosis of benign lichenoid keratosis also known as lichenoid keratosis (LK) or lichen planus-like keratosis. (It’s worth noting that in some cases, a dermoscopic evaluation will reveal blue-grey dots rather than the uniform, velvety brown pigmentation that was seen here.)

LK is a benign reactive inflammatory lesion that usually manifests as a solitary lesion in middle age. LKs can be found on the trunk or lower extremities. As the alternative name “lichen planus-like keratosis” implies, the lesions can be purple, polygonal, raised, and have stria. The etiology is unknown but thought to be a reaction to a lentigo or another lesion, resulting in an inflammatory infiltrate.1

If dermoscopic evaluation of the lesion is unclear, biopsy is warranted. Maor et al1 reported the pathology results of 263 consecutive patients with a histologic diagnosis of LK. Of those cases, 47% were clinically thought to be basal cell carcinoma (BCC) and 18% were submitted with a diagnosis of seborrheic keratosis.1 The high rate of concern for BCC and not listing a diagnosis of LK may have been the result of clinicians doing biopsies on the atypical lesions and clinically following the typical banal lesions.

At the patient’s request, he was given a written list of the diagnoses of his various skin lesions and advised that his LK was benign and did not require treatment. He was advised to continue coming in for serial skin examinations and report any concerning lesions in the interim.

Image and text courtesy of Daniel Stulberg, MD, FAAFP, Professor and Chair, Department of Family and Community Medicine, Western Michigan University Homer Stryker MD School of Medicine, Kalamazoo.

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