Renal thrombotic microangiopathies/thrombotic thrombocytopenic purpura in a patient with primary Sjögren's syndrome complicated with IgM monoclonal gammopathy of undetermined significance.

Thrombotic microangiopathy (TMA)/thrombotic thrombocytopenic purpura (TTP) is a rare but potentially lethal condition requiring rapid recognition, diagnosis, and initiation of therapy. We experienced a case of a 61-year-old woman with primary Sjögren's syndrome (pSS) complicated with severe renal TMA/TTP following IgM monoclonal gammopathy of undetermined significance (MGUS). She was admitted to our hospital for further evaluation of hypergammaglobulinema, acute renal failure, and severe thrombocytopenia. She had been diagnosed with pSS 13 years prior to admission. Histological examination of her kidney revealed fibrin thrombi in the glomeruli and arterioles, a finding that is consistent with TMA/TTP. The patient was subsequently treated with plasma exchange, which resulted in a successful outcome without any complications. This rare case suggests that it is important to make a therapeutic decision based on appropriate and prompt pathological diagnosis.