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Abstract
Introduction: Keratoacanthomas (KA) are well-differentiated neoplasms of squamous epithelium. While commonly asymptomatic and spontaneously regressing, lesions may induce local destruction if untreated. We present the case of a patient with numerous keratoacanthomas restricted to the red-inked areas of a recently obtained tattoo who exhibited a robust response to intralesional 5-fluorouracil (IL 5-FU).
Case Presentation: A 68-year-old male with a history of nonmelanoma skin cancers presented with rapidly growing lesions on his right posterior calf. These lesions developed over two months following the placement of new tattoos. The right posterior calf revealed a 4mm hyperkeratotic, exophytic nodule with a keratin core and thrombosed vessels under dermoscopy within the red-inked portion of the tattoo. Five additional hyperkeratotic papules were identified circumferentially throughout the red border of the tattoo, sparing the blue, green, yellow, and black inked portions. A punch biopsy confirmed a diagnosis of keratoacanthomatous squamous cell carcinoma. Treatment with IL 5-FU (50 mg/mL) demonstrated complete resolution of five out of six lesions after a second injection.
Discussion: The association between tattooing and developing keratoacanthomas and skin cancer is likely multifactorial.1,2,3 Definitive diagnosis is warranted to rule out malignancy and optimize the initiation of appropriate therapy. Excisional treatment ensures decisive treatment but does not eliminate the potential for new lesions in previously unaffected areas.4 Providers should consider less invasive options in patients with a high disease burden. In this case, we demonstrate a significant resolution of most lesions after treatment with IL 5FU, highlighting the utility of this approach to limit disfigurement and provide prompt management.