[Cutaneous pseudolymphoma as an alternative presentation of IgG4 related disease]

Hyper-IgG4 syndrome is a rare entity characterized by fibro-inflammatory lesions of organs, an excess of IgG4 positive plasma cells in histology and high serum level IgG4. Many organs can be affected (pancreas, kidney, salivary glands) and the list continues to grow. The skin damage is rarely reported in the literature and is usually associated with other typical lesions of this syndrome. We report the case of a 53-year-old female followed since 2005 for lymphadenopathy, associated with axillary nodular skin lesions. The assessments made at that time had retained the diagnosis of pseudolymphoma with implementation of multi-line therapy. Six years later, and the persistence of the lesions, plasma cells marked by anti-IgG4 and the serum IgG4 has attached injuries to the syndrome hyper-IgG4. The patient is treated with low dose corticosteroids with a good and protacted response. Cutaneous pseudolymphoma could be a new presentation of the syndrome of hyper-IgG4 in the absence of any other injury usually associated with this entity. This case illustrates the interest for proposing a plasma cell labeling with anti-IgG4 in any case of cutaneous pseudolymphoma.