Rapidly progressed secondary amyloidosis in a patient with mixed connective tissue disease.

A 39-year-old woman with mixed connective tissue disease suddenly developed repeated watery diarrhea two years after the onset of the disease. A colonic biopsy specimen revealed amyloid A protein deposition and the diagnosis of secondary amyloidosis was established. The amyloid deposition disappeared after the 8-month course of the treatment with prednisolone and azathioprine. Molecular genetic analysis showed the presence of the gamma-allele in her serum amyloid A protein 1 gene. This might be associated with the early onset and progression of secondary amyloidosis in our case, just like cases reported in rheumatoid arthritis.