Mixed connective tissue disease associated with von Recklinghausen's neurofibromatosis.

We report a 42-year-old Japanese woman with Recklinghausen's neurofibromatosis 1 (NF1) who developed mixed connective tissue disease (MCTD). Previously experiencing good health without an increase in subcutaneous nodules, she presented with Raynaud's phenomenon, swollen hands and polyarthralgia Clinical examination revealed a high titer of anti-RNP antibody, and she was thus diagnosed as having MCTD. She was treated with oral prednisolone (10 mg/day) and her symptoms improved rapidly. Since the association of MCTD and NF1 has not been reported previously, we concluded that this association is rare. We also discussed the association of NF1 and autoimmune diseases including MCTD.