Quantitative histopathology of the inflammatory myopathies
S. P. Ringel, M. R. Carry, A. J. Aguilera and J. M. Starcevich
This study quantitatively assessed skeletal muscle histopathology in 57
patients with inflammatory myopathy, including 20 patients with
polymyositis (PM), 19 patients with dermatomyositis (DM), and 18 patients
with evidence of an additional connective-tissue disease. No histologic
criteria for invariably distinguishing patients with inflammatory myopathy
were established because of overlap in individual measurements, but general
histopathologic distinctions were confirmed. In PM, endomysial mononuclear
cell infiltration (fibers bordering on inflammation) was usual, whereas in
DM inflammation of large vessels, fibers with circumscribed areas of
myofibrillar loss, and perifascicular atrophy were seen. Patients with
evidence of an additional connective-tissue disease were most similar to
the DM patients, with a greater prevalence of perivascular inflammation
than in the PM patients. Because of varying histopathology (and presumed
varying pathogenesis), future therapeutic trials would be more informative
if they were designed using patients with homogeneous histologic features.
