Inclusion body myositis in French patients. A clinicopathological evaluation.
In order to establish the frequency of inclusion body myositis (IBM) in a European neuropathological unit and to evaluate the specificity of IBM pathology, we reviewed the 850 muscle biopsies performed in our laboratory over the past 7 years. Clinical histopathological and ultrastructural evaluation of all cases showing rimmed vacuoles, a constant histopathological feature of IBM, was done and the diagnosis of IBM was assessed using the clinico-pathological criteria of Calabrese, Mitsumoto & Chou (1987). Among the nine cases showing rimmed vacuoles, five were classified as IBM (group 1), either definite (3/5) or probable (2/5), and four suffered from a chronic denervating process of muscle (group 2). The overall frequency of IBM (0.6% of all muscle biopsies) was similar to that reported by North American authors. IBM represented 16% of adult idiopathic inflammatory myopathies investigated in our laboratory. Clinical and histopathological findings in group 1 were homogeneous and distinctive. Muscle biopsy was consistent with an inflammatory myopathy in all patients in group 1 and with a non-inflammatory denervating process in 3/4 patients in group 2. Typical intrasarcoplasmic inclusions were detected by electron microscopy in 3/5 cases in group 1 and 1/4 in group 2, which raises questions about the specificity of the 16-18 nm tubulofilaments. Failure to demonstrate inclusions in two patients with otherwise typical IBM, was probably related to the paucity of rimmed vacuoles observed in these cases.
Mhiri
C
C
Département de Pathologie (Neuropathologie), Hôpital Henri Mondor, Créteil, France.
Gherardi
R
R
D000328:Adult; D000368:Aged; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D002479:Inclusion Bodies / Q000473:pathology*; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D009132:Muscles / Q000473:pathology / Q000648:ultrastructure; D009220:Myositis / Q000453:epidemiology / Q000473:pathology*