To the Editor We read with interest the article recently published in JAMA Dermatology that reported successful treatment of IgG4-related disease (IgG4-RD) of the skin with thalidomide.1 A recently described disease entity, IgG4-RD can affect virtually any organ of the body, and while skin involvement is rare, it may manifest clinically as nonspecific skin papules, plaques, and nodules.2 Ingen-Housz-Oro et al1 rendered a diagnosis of IgG4-RD in the skin of 2 patients with skin nodules based on evaluation of skin biopsy specimens showing dense lymphocytic infiltrates with lymphoid follicles, dermal fibrosis, and a IgG4 to IgG ratio exceeding 75%. Although these patients may indeed have had isolated skin involvement by IgG4-RD, we highlight herein recent advances in the diagnosis of IgG4-RD to emphasize the importance of correlating clinical features, histopathologic evidence, and immunophenotypic data derived from careful interpretation of IgG4 and IgG stains.
Lehman JS, Pittelkow MR, Smyrk TC. IgG4-Related Skin Disease. JAMA Dermatol. 2013;149(12):1439-1440. doi:10.1001/jamadermatol.2013.7326