Mycophenolate mofetil induced myopathy in a patient with lupus nephritis.

We describe a case of mycophenolate mofetil (MMF) induced myopathy in a patient with lupus nephritis. Two months after starting MMF treatment she developed asthenia, lower limb weakness, and abnormal increase of muscle enzymes. An electromyogram showed a myogenic pattern with small polyphasic discharges without neurogenic signs involving proximal muscles of lower limbs. Muscle biopsy revealed the presence of fibers of variable size with irregular sarcoplasmic basophilic areas. Using oxidative enzyme techniques, many type I fibers showed a moth-eaten appearance resembling minicores. The ultrastructural findings consisted of myofibrillary lesions with multiple small foci of Z-band streaming. MMF withdrawal was followed by complete clinical and enzymatic recovery.