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Flat lesions on thigh

A 26-year-old woman sought treatment for multiple flat lesions on 1 thigh. She said that at first there had been just a few lesions, but over the past 3 months, they had spread. She had no pain or itching. She reported that she shaved that part of her leg.

What's your diagnosis?


This patient was diagnosed with flat warts, based on their typical appearance and location. The differential diagnosis included lichen planus and seborrheic keratoses. Lichen planus is bilateral and the most common sites are the ankles, wrists, and back. Seborrheic keratoses are typically found in clusters on the face and trunk, so this would have been an unusual location for a cluster of these lesions.

Flat warts may be treated with salicylates, 5-fluorouracil, imiquimod, cryotherapy, or tretinoin. The clinician discussed the treatment choices with the patient, and she chose to have initial cryotherapy followed by topical, over-the-counter salicylic acid.

This case was adapted from: Mayeaux EJ. Flat warts. In: Usatine R, Smith M, Mayeaux EJ, Chumley H, Tysinger J, eds. The Color Atlas of Family Medicine. New York, NY: McGraw-Hill; 2009:527-529.

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