Very few cases in the literature has reported the presence of IgG4 in scleroderma ...

There are similarities between IgG4RD and scleroderma. For example, T-lymphocytes seem to be of particular importance in both the diseases. These cells are predominantly CD4+ with a predominant Th2 cytokine profile characterized by high levels of IL-4, IL-5. This key role of T cell proliferation and cytokine secretion suggests that both these condition could be associated with a defective control of T cell activation. B cells are also activated and, through the production of autoantibodies, forced fibroblasts to switch in a profibrotic phenotype. Macrophages in perivascular infiltrates produced transforming growth factor beta that promote fibrosis. However, to diagnose an IgG4RD, histopathological hallmarks must be respected: 1) dense storiform fibrosis and 2) lymphoplasmacytic infiltrate rich in IgG4+ plasma cells (with a definite cut off of IgG4+/IgG+ ratio in the various tissues examined). The IgG4 antibodies in scleroderma are not the most representative and most expressed. In contrast to systemic sclerosis, in which the tissues fibrosis remain largely intractable to treatment, many IgG4-RD patients appear to have a condition in which the collagen deposition is reversible. Therefore, there are some similarities but also substantial histological and pathogenetic differences which must be investigated.

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Article Scleroderma and IgG(4)-Related Disease