PERCUTANEOUS NEEDLE MUSCLE BIOPSY IN THE EVALUATION OF PATIENTS WITH SUSPECTED INFLAMMATORY MYOPATHY

Objective. To determine the usefulness of a unique method of percutane ous needle muscle biopsy (NMB) in patients with suspected idiopathic i nflammatory myopathy (IIM). Methods. The yield of percutaneous NMB was studied in 55 patients who were found to have a combination of clinic al, laboratory, or electromyographic features of IIM. Results. A diagn osis of IIM was confirmed histopathologically in 29 patients (53%), ot her specific myopathies were found in 5 (9%), nonspecific myopathic ch anges were present in 11 (20%), and a neurogenic process was diagnosed in 3 (5%), Nonspecific changes or no abnormalities were present in 7 patients (13%), Followup of the 18 patients with nonspecific histopath ologic findings disclosed that only 3 had a subsequent disease course compatible with IIM. Conclusion. Percutaneous NMB is a safe, convenien t, and relatively inexpensive method of muscle biopsy, with a high dia gnostic yield for the pathologic confirmation of IIM, It should be con sidered as a primary method of acquiring muscle for histopathologic ex amination in the evaluation of suspected IIM.