[Significance of rimmed vacuoles in neuromuscular disorders--a comparative immunohistochemical study of inclusion body myositis and distal myopathy with rimmed vacuole formation].

Of 3,403 muscle biopsies from patients with a variety of neuromuscular disorders, 87 (2.6%) had at least three muscle fibers with rimmed vacuoles in a single low power field (magnificantion x 20). The rimmed vacuole formation may be a crucial pathologic findings to understand the pathogenesis of inclusion body myositis (IBM), distal myopathy with rimmed vacuole formation (DMRV), Marinesco-Sjögren syndrome and oculopharyngodistal myopathy, because the muscle fibers in these biopsies showed no striking necrotic and denervating changes. Since Congo red positive material and ubiquitin- and beta-amyloid protein-positive deposits were found in muscle fibers with rimmed vacuoles in DMRV and various neuromuscular disorders besides IBM, these findings may have no disease-specific significance and may be not helpful in differentiating DMRV from IBM.