Childhood dermatomyositis associated with intracranial tumor and liver cysts.

We present a girl with dermatomyositis, liver cysts and choroid plexus papilloma who was treated and followed for 7 years. Muscle histology revealed an inflammatory muscle disease and similar changes were detected in a brain tumor that was surgically removed at onset. Western blot analysis of the muscle revealed severely reduced calpain-3 protein. She was treated with pulse methylprednisolone treatment (800 mg i.v. for 4 days) followed by oral prednisone treatment (16 mg on alternate day) for 14 months, which improved muscle strength. Moreover, the cystic liver formations disappeared during steroid treatment. This is an unusual association of muscular disorder, steroid-responsive liver cysts, intracranial tumor and secondary calpain-3 deficiency. We speculate that this association is not coincidental, but mediated by an autoimmune attack against an antigen that is shared among the target tissues.