Anti-RNA polymerase III antibodies in the diagnosis of scleroderma renal crisis in the absence of skin disease.

Scleroderma renal crisis (SRC) occurs in approximately 10% of patients with systemic sclerosis (SSc), particularly in those with diffuse skin disease. Scleroderma renal crisis has rarely been described to occur in patients with SSc without skin involvement. Scleroderma renal crisis without skin disease represents a major diagnostic challenge, particularly in patients without overt SSc involvement of other organ systems. It closely mimics the presentation of thrombotic thrombocytopenic purpura/hemolytic uremic syndrome, and treatment is therefore often directed at this entity. Anti-RNA polymerase III antibody testing has been previously reported to be used in 4 patients to diagnose SRC in the absence of sclerotic skin disease.We report 2 patients without skin disease or overt visceral involvement at presentation who presented with microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Both patients eventually developed diffuse and rapidly progressive skin thickening. Anti-RNA polymerase III antibodies were strongly positive, supporting that their renal presentations were secondary to SRC.