Abstract

Crystal deposition as a result of medication injection is rarely encountered in the skin. We report the case of a 63-year-old man with rosacea who repeatedly injected ceftriaxone diluted with lidocaine into a presumed abscess on his left cheek over a period of several weeks which subsequently developed into a painless firm plaque. A punch biopsy revealed a lobular distribution of well-circumscribed rounded aggregates of brilliantly polarizable crystalline deposits with surrounding fat necrosis but devoid of an inflammatory infiltrate. Although there are numerous reports of ceftriaxone precipitating and resulting in pseudolithiasis and urine crystals, this is a unique report of crystal deposition following subcutaneous injection of an antibiotic. The histopathologic characteristics, proposed pathogenesis, and treatment challenges will be discussed.

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