Immune myopathies with perimysial pathology: Clinical and laboratory features

Abstract

ObjectiveImmune myopathies with perimysial pathology (IMPP) have a combination of damage to perimysial connective tissue and muscle fiber necrosis, more prominent near the perimysium. We studied the clinical and laboratory correlates of patients with pathologically defined IMPP.MethodsThis is a retrospective chart and pathology review of 57 consecutive patients with IMPP myopathology and, for comparison, 20 patients with dermatomyositis with vascular pathology (DM-VP).ResultsCompared with DM-VP, IMPP patients more commonly had interstitial lung disease (ILD) (p &lt; 0.01), Raynaud phenomenon (p &lt; 0.05), mechanic's hands (p &lt; 0.05), arthralgias (p &lt; 0.001), and a sustained response to immunomodulatory therapy (p &lt; 0.05), and less frequently had a concurrent malignancy (p &lt; 0.01). IMPP patients had higher serum creatine kinase values (p &lt; 0.05), more frequent serum Jo-1 (p &lt; 0.03) or SSA/SSA52 autoantibodies (p &lt; 0.05), and less frequent antinuclear antibodies (p &lt; 0.01). IMPP patients with serum Jo-1/antisynthetase antibodies were more likely to have ILD (p &lt; 0.05) and inflammatory arthritis (p &lt; 0.05) than IMPP patients without these antibodies.ConclusionsIMPP myopathology is associated with an increased risk of ILD, Raynaud phenomenon, mechanic's hands, and inflammatory arthritis when compared with another immune myopathy (DM-VP). IMPP patients require regular screening for ILD, particularly those with antisynthetase antibodies. The absence of myositis-specific autoantibodies in a large percentage of IMPP patients emphasizes the important role for myopathology in identifying patients at higher risk of severe comorbid conditions such as ILD.</jats:sec