Lesions in Muscle in Arthritis.

Recent pathological studies suggest that rheumatoid arthritis may be a disease with widespread involvement of tissues other than the joints. Curtis and Pollard (1940) were the first to describe a nonarticular histological lesion which was common to all cases of rheumatoid arthritis-their cases including four with Felty's syndrome. In every one of 11 cases these authors found small perivascular infiltrations with lymphocytes in the corium of the skin and in the muscles. They regarded these perivascular accumulations of cells as evidence of a generalized disease process and as indicating that Felty's syndrome is not essentially different from classical rheumatoid arthritis. Freund et al. (1942) found characteristic pathological lesions in the peripheral nerves of 3 out of 5 cases of rheumatoid arthritis. The lesions were located in the perineurium, and in their most typical form presented 3 zones: (1) a central acellular zone composed of homogeneous coagulated material occasionally showing nuclear debris; (2) an intermediate zone of cells with large hypochromatic nuclei with more or less definite nucleoli; and (3) a peripheral outer zone containing numerous lymphocytes and plasma cells. The lesion was sharply differentiated from the surrounding tissue, and they regarded it as in some respects similar to the subcutaneous nodule of rheumatoid arthritis. Nerves examined included the femoral, tibial, sciatic, and axillary; and the concentration of lesions differed widely in different nerves and different parts of the same nerve. All were perineural except one nodule which was situated in the epineural fatty tissue. The authors regarded these lesions as specific for rheumatism, and they recalled the finding by Koeppen (1932) of perivascular lymphocytic infiltrations in the sciatic nerve in 2 out of 8 cases of active acute and subacute rheumatism. They suggested that the nerve lesions might be related to pain, paraesthesia, vasomotor, secretory, and trophic disorders in the disease. In following up the nerve lesions in the small nerve branches in muscle, the same authors, Freund et al. (1945), noted the presence of inflammatory lesions in the muscle itself, unassociated with nerve fibrils. There were compact accumulations of lymphocytes, plasma cells in small numbers, and occasional eosinophil and epithelioid cells. Few reticulin fibres were found in the lesions, but there was an increase of collagenous connective tissue in the endomysium and perimysium between the inflammatory cells. The lesions varied in size from 20 lymphocytes to a nodule which, in a stained section, was visible to the naked eye. Such focar lesions were found in all of 14 patients with rheumatoid arthritis on whom muscle biopsy was performed. The deltoid, triceps, and gastrocnemius were the muscles examined. The authors drew attention to the importance of the finding of such nodules in a random sample of skeletal muscle not exceeding 5 g. in weight. Associated changes in muscle fibres included a hydropic degeneration, oedema, loss of striation with marked swelling, or shrinkage and atrophy of the fibres. Steiner, Freund, et al. (1946) extended and confirmed their previous observations. Focal lesions of the same kind were found in 9 more cases of rheumatoid arthritis; and a series of 196 control observations were made, including examination of muscle from cases of various nervous and muscular diseases. The control material failed to show any lesions comparable to those in rheumatoid muscle. Additional points of interest in their second series were the finding of: (1) vascular lesions consisting of adventitial and periadventitial lymphocytic infiltration-less frequently intramural lesions were found -and (2) small inflammatory foci where a muscle fibre, surrounded by cell infiltration, showed early evidence of degeneration, indicating clearly that muscle degeneration was a consequence of the inflammatory lesions. In the course of a systematic study of pathological material from various types of rheumatic disease, specimens of muscle tissue from 11 cases of generalized arthritis have been examined.