Anti-polymyositis/Scl antibody-positive overlap syndrome of diffuse cutaneous systemic sclerosis, dermatomyositis, systemic lupus erythematosus, and antiphospholipid syndrome.

A 37-year-old Japanese man with a 3-year history of diffuse cutaneous systemic sclerosis was admitted to our hospital with high fever, arthralgia, myalgia, and muscle weakness. A physical examination revealed facial erythema, Gottron's sign, and mechanic's hands in addition to skin sclerosis. Laboratory data revealed significantly elevated levels of creatine kinase and decreased complement. Anti-RNP, anti-Smith, anti-DNA, anti-β -glycoprotein 1, anti-polymyositis (PM)/Scl75, and anti-PM/Scl100 antibodies were detected. He also had urinary protein, interstitial lung disease, pericarditis, multifocal cerebral infarctions, and leukoencephalopathy. Thus, a diagnosis of overlap syndrome of diffuse cutaneous systemic sclerosis, dermatomyositis, and systemic lupus erythematosus with antiphospholipid syndrome was made. Because of the intractable course, he was treated with multiple immunosuppressive and immunomodulatory drugs, including three rounds of 1000 mg methylprednisolone pulse therapy. This is the first case report of anti-PM/Scl antibody-positive overlap syndrome of three major connective tissue diseases.