Propylthiouracil-induced lupus-like syndrome developing in a Graves' patient with a sibling with systemic lupus erythematosus.

A 13-year-old girl with Graves' disease, whose younger sister had systemic lupus erythematosus, developed polyarthralgia, fever, neutropenia, hypergammaglobulinemia, and microscopic hematuria after treatment with propylthiouracil (PTU) for 2 years. Myeloperoxidase-anti-neutrophil cytoplasmic antibodies were strongly positive. Anti-single- and anti-double-stranded DNA antibodies were positive, whereas LE cells and anti-Sm antibodies were negative. PTU was discontinued and all symptoms subsided gradually. Two years later, the microscopic hematuria had disappeared completely. Both patients had the identical HLA-DR alleles (HLA-DR9). These present two cases in siblings suggest that both sisters had lupus diathesis, and that the elder sister developed a PTU-induced lupus-like syndrome.