[A case of Behçet's disease associated with myopathy during cyclosporin treatment]

A 46-year-old male was admitted to the Department of Neurology complaining of gait disturbance. He was given a diagnosis of Behçet's disease and placed on colchicine (0.5-1.0 mg/day) for 7 months without improvement. Subsequently cyclosporin (290 mg/day) was added this regimen. However, 7 months after initiation of combined colchicine/cyclosporin therapy serum creatine kinase (CK) rose to 1,255 U/l. On admission, neurological examination revealed generalized muscle atrophy with predominant proximal muscle weakness and decreased deep tendon reflexes. No myalgia was noted. Laboratory tests demonstrated anemia, liver dysfunction, chronic renal failure and an elevated serum CK level. The plasma cyclosporin concentration was 220 ng/dl, which is within therapeutic limits. Motor unit potentials in electromyography of bilateral quadriceps muscles were generally of short duration and reduced amplitude. A biopsy of quadriceps muscle showed variability in the size of type 2 fibers and scattered small vacuoles. Some of the vacuoles resembled rimmed vacuoles. These vacuoles were stained positively for acid phosphatase. Electronmicroscopy revealed that these vacuoles contained dense bodies, myeloid bodies, and glycogen particles. Collectively suggesting that these structures are autophagic vacuoles. Cyclosporin was reduced to 200 mg/day with unchanged colchicine dose and bromocriptine, which potentiates cyclosporin effects, was started. Gradual recovery from muscle weakness ensued. These findings suggest that cyclosporin contributed to the pathogenesis of this myopathy. On increase in use of cyclosporin, one should consider the possibility of myopathy as one of its side effects especially in combination therapy with myotoxic drugs such as colchicine.