Tattoos and sarcoidosis

I read, with keen interest, the CMAJ article “Tattoo reactions as a sign of sarcoidosis,” which described granulomatous tattoo reaction in a patient with systemic sarcoidosis.¹ Tattoo sarcoidosis has been known for more than half a century, although only a few cases have been described. One hypothesis is that this may be a “pigment-induced disease.”² Tattoo pigments may provide chronic antigenic stimulation leading to Th1/Th2 imbalance in a genetically predisposed individual, thus triggering the development of sarcoidosis. This is based on the demonstration of pigment in the tattoo granuloma as well as similar pigment in the noncutaneous site of granulomatous inflammation. On histopathologic examination, pigment granules, pigment laden macrophages or polarizing material may be demonstrable. I am interested in knowing if these findings were seen in any of the histopathologic sections from the patient described by Post and Hull, and when the patient was tattooed.¹ In 2005, Antonovich and Callen reviewed the published cases of tattoo sarcoidosis.³ Most cases occurred along with pulmonary involvement and tattoo reactions preceded the diagnosis of sarcoidosis in 14 out of 19 cases. The authors also highlighted that granulomatous inflammation on histopathology with demonstrable foreign material should not be used as a criterion to exclude a diagnosis of sarcoidosis, as was the previous school of thought.