A histopathologic study of striated muscle biopsies in leprosy.

Histopathologic changes in striated muscle biopsies in 50 cases of leprosy were studied; 40 being the lepromatous type and 10 the nonlepromatous type. All the biopsies were obtained from midportions of normal looking biceps muscles and paraffin embedded. Sections cut in transverse and longitudinal planes were stained by hematoxylin and eosin, Masson's trichrome, Mallory's PTAH, Gomori's silver impregnation, and Ziehl-Neelsen's technic. Lepromas, focal or confluent, in the endomysium, perimysium, muscle fibers and perineurally, constituted the most common pathological lesion, being observed in 34% of all cases with a higher frequency in the lepromatous type. Acid-fast bacilli could be demonstrated in some of these lepromas. These nodules were observed even in younger patients and increased in frequency as the age of patient advanced. Three cases of nonlepromatous leprosy showed granulomas. Other changes noted in varying proportions were loss of striations, hyaline change, fatty change, sarcolemmal changes, along with endomysial thickening, muscle necrosis and fibrosis. Bacillemia in leprosy and the possible route of muscle invasion resulting in subsequent production of leprous nodules with associated degenerative changes, indpendent of nerve involvement, have been postulated.