Immunoglobulin G4-positive multi-organ lymphoproliferative syndrome with antiphospholipid antibody syndrome

We report immunoglobulin (Ig)G4-positive multi-organ lymphoproliferative syndrome (IgG4(+) -MOLPS) with antiphospholipid antibody syndrome (APS) in a 56-year-old Japanese man presenting with purpuric patches on his legs. Skin biopsy revealed leukocytoclastic vasculitis. Laboratory tests demonstrated high levels of serum IgG and IgG4, hypocomplementemia and anticardiolipin antibody. Echography of the lower limbs and pulmonary scintigraphy showed a thrombus in the left soleal vein and multiple emboli in the basal part of both inferior pulmonary arteries. Computed tomography revealed systemic lymphadenopathy. Histologically, there was reactive paracortical hyperplasia with proliferation of histiocytes and infiltration of IgG4-positive plasma cells. We made a diagnosis of IgG4(+) -MOLPS with APS. To our knowledge, this complication has not been reported previously.