IgG4-Related Skin Disease Presenting as a Pseudolymphoma in a White Adolescent Girl.

Immunoglobulin gamma (Ig) type 4-related disease (IgG4-RD) is a chronic immunologic systemic disorder that has gained worldwide recognition in the past decade. This entity can affect almost every organ system, and its characteristic lesions have been found in a variety of organs such as lacrimal and salivary glands, pancreas, liver, bile ducts, lungs, kidneys, retroperitoneum, breast, aorta, thyroid, and prostate. This case reports a very rare case of IgG4-RD presenting with a cutaneous lesion in a young female patient mimicking a lymphoproliferative disorder. IgG4-RD affecting the skin is a rare entity and has mostly been reported in Japanese men of middle to older age. IgG4-RD with cutaneous involvement should be in the differential of non-neoplastic, lymphomas, autoimmune, and infectious disorders of the skin.