Renal disease is uncommon in patients with MCTD and is often mild when present. Kidney biopsies have shown mesangial change, focal nephritis, and diffuse membranous nephritis. Immunofluorescent stains have identified granular deposits of IgG, C3, and C4 in the glomerular basement membrane. Central nervous system involvement is uncommon. Trigeminal neuralgia is the most common neurologic finding.
Rare problems are transient confusion, cerebral infarction, aseptic meningitis, and seizures.
Aseptic meningitis in MCTD responds to corticosteroids. Other disorders include peripheral neuropathy and psychosis. Abnormal laboratory findings commonly include elevated sedimentation rates, leukopenia, and diffuse hypergammaglobulinemia. In rare instances, there is significant Coombs'-positive hemolytic anemia and thrombocytopenia. Rheumatoid factor tests are positive in about one half of patients.