Background/Purpose:

The idiopathic inflammatory myopathies are associated with an increased incidence of malignancy, and interstitial lung disease (ILD) has been reported in as many as 20-78% of patients with polymyositis and dermatomyositis when followed from diagnosis.  As a result of these associations, patients often receive CT scans of the chest where lung nodules are incidentally discovered. The radiographic nature of these lung nodules and whether they tend to increase in size, regress, or remain stable in size has not been described. The aim of this study was to define the prevalence of lung nodules in patients with inflammatory myopathies in a large clinical cohort evaluated at a Myositis Center, the clinical features associated with the presence of lung nodules, and whether the nodules changed in size over time.

Methods:

Data was obtained from the cohort of 976 patients referred to the Myositis Center at Johns Hopkins.  Only patients with confirmed inflammatory myopathies and at least one chest CT scan performed at our Center for clinical purposes were included in the study.  For patients with more than one CT, all CTs were reviewed. The presence of interstitial lung disease was defined by decreased total lung capacity (TLC) or diffusion capacity (DLCO) on pulmonary function testing and/or presence of ground glass opacities on chest CT.

Results:

298 of the 976 patients had at least one chest CT performed at our Center.  The prevalence of lung nodules in these patients was 25.5% (76/298). Only 5 patients had a nodule> 10 mm, and in those patients with follow up CTs, none of these nodules increased in size. Interstitial lung disease was present in 34.9% of the total cohort.  The prevalence of nodules was not significantly different in those who had interstitial lung disease and those who did not (26.9% and 24.7% respectively, p=0.68).  Of the 76 patients with lung nodules, 39.4 % (30/76) had a follow-up chest CT.  The interval for follow-up was variable and ranged from 3 to 19 months. On subsequent CTs, none of the nodules had progressed in size by more than .2 cm and 51.6% (16/31) had regressed entirely. 

Conclusion: Lung nodules are frequently observed in patients with inflammatory myopathies, but not greatly increased in prevalence over healthy adults where they are reported in 18% of patients.  Lung nodules were no more common in patients with ILD than those patients without ILD. The lung nodules do not likely represent malignancy as they do not progress when followed over time. In fact, about half of patients had regression of the nodules,

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« Back to 2012 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/lung-nodules-in-patients-with-idiopathic-inflammatory-myopathies/