Muscle pathology in 57 patients with myotonic dystrophy type 2.
We evaluated muscle biopsies from 57 patients with genetically confirmed myotonic dystrophy type 2/proximal myotonic myopathy (DM2/PROMM). Light microscopy showed myopathic together with "denervation-like" changes in almost all biopsies obtained from four different muscles: increased fiber size variation, internal nuclei, small angulated fibers, pyknotic nuclear clumps, and predominant type 2 fiber atrophy. Quantitative morphometry in 18 biopsies that were immunostained for myosin heavy chain confirmed a predominance of nonselective type 2 fiber atrophy. These histological changes were similar in all patients regardless of the site of biopsy, the predominant clinical symptoms and signs, and the clinical course. It is likely that, in a number of undiagnosed patients, DM2 is the underlying disorder. With a better understanding of the histopathological pattern in DM2, biopsies from patients with undiagnosed neuromuscular disorders can now be reevaluated.
Schoser
Benedikt G H
BG
Department of Neurology, Friedrich Baur Institute, Ludwig Maximilians University of Munich, Ziemssenstr. 1a, D-80336 Munich, Germany. bschoser@fbs.med.uni-muenchen.de
Schneider-Gold
Christiane
C
Kress
Wolfram
W
Goebel
Hans-Hilmar
HH
Reilich
Peter
P
Koch
Manuela C
MC
Pongratz
Dieter E
DE
Toyka
Klaus V
KV
Lochmüller
Hanns
H
Ricker
Kenneth
K
D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology*; D009223:Myotonic Dystrophy / Q000235:genetics* / Q000473:pathology*