LAUSR

A 33-year-old previously healthy man presented with an asymptomatic rash on his tattoo. Physical examination revealed brown and black papules confined to the ink of his tattoos (Fig. 1a, b). Chest x-ray showed hilar lymphadenopathy. Biopsy of a papule on his tattoo demonstrated noncaseating granulomas consistent with a diagnosis of sarcoidosis. Sarcoidosis is a granulomatous disease that can affect multiple organ systems, with skin involvement seen in approximately 25% of cases. Sarcoidal reaction at the site of tattooing is a well-described phenomenon. 3 Skin findings in sarcoidosis typically do not have prognostic significance, with the exception of erythema nodosum and lupus pernio, which have been associated with spontaneously resolving sarcoidosis and more severe systemic involvement, respectively. The etiology of tattoo sarcoidosis is unknown, but it may arise from chronic antigenic stimulation in predisposed patients. The differential diagnosis for tattoo-associated skin lesions in sarcoidosis includes T-cell lymphoma, infection, keloid, and discoid lupus erythematosus. 3 It is vital for practitioners to be aware of skin and tattoo involvement in sarcoidosis, as it is an easy and non-invasive site for biopsy and can aid in an early diagnosis and thus prompt treatment.