Steroid-induced myopathy. Two case-reports.

Steroid-induced myopathy is a rare condition defined as gradually increasin g muscle weakness in a patient on glucocorticoid therapy. All glucocorticoi ds, including fluorinated derivatives, have been incriminated. The clinical spectrum ranges from muscle fatigability to diffuse myopathy. Two cases ar e reported, in a 48-year-old man with rheumatoid arthritis and sicca syndro me and a 60-year-old woman with anterior pituitary insufficiency. Electrodi agnostic testing confirmed the myopathy. In the woman, histological feature s were consistent with the diagnosis. Laboratory test results were those ex pected in rheumatoid arthritis in the man and were normal in the woman. Fol lowing substitution of methylprednisolone for the hydrocortisone used forme rly, the muscle weakness resolved fully in both patients. Steroid-induced m yopathy is a rare condition that has a favorable outcome after hydrocortiso ne substitution. Its pathophysiology may involve cytochrome 450 production within skeletal muscles.