Rheumatoid pulmonary nodules: clinical and imaging features compared with malignancy
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The objective of this study was to identify clinical and imaging features that distinguish rheumatoid lung nodules from malignancy.
We conducted a retrospective review of 73 rheumatoid patients with histologically-proven rheumatoid and malignant lung nodules encountered at Mayo Clinic, Rochester, MN (2001–2016). Medical records and imaging were reviewed including a retrospective blinded review of CT and PET/CT studies.
The study cohort had a mean age of 67 ± 11 years (range 45–86) including 44 (60%) women, 82% with a smoking history, 38% with subcutaneous rheumatoid nodules, and 78% with rheumatoid factor seropositivity. Subjects with rheumatoid lung nodules compared to malignancy were younger (59 ± 12 vs 71 ± 9 years, p < 0.001), more likely to manifest subcutaneous rheumatoid nodules (73% vs 20%, p < 0.001) and rheumatoid factor seropositivity (93% vs 68%, p = 0.034) but a history of smoking was common in both groups (p = 0.36). CT features more commonly associated with rheumatoid lung nodules compared to malignancy included multiplicity, smooth border, cavitation, satellite nodules, pleural contact, and a subpleural rind of soft tissue. Optimal sensitivity (77%) and specificity (92%) (AUC 0.85, CI 0.75–0.94) for rheumatoid lung nodule were obtained with ≥ 3 CT findings (≥ 4 nodules, peripheral location, cavitation, satellite nodules, smooth border, and subpleural rind). Key 18FDG-PET/CT features included low-level metabolism (SUVmax 2.7 ± 2 vs 7.2 ± 4.8, p = 0.007) and lack of 18F-fluorodeoxyglucose (FDG)-avid draining lymph nodes.
Rheumatoid lung nodules have distinct CT and PET/CT features compared to malignancy. Patients with rheumatoid lung nodules are younger and more likely to manifest subcutaneous rheumatoid nodules and seropositivity.
• Rheumatoid lung nodules have distinct clinical and imaging features compared to lung malignancy.
• CT features of rheumatoid lung nodules include multiplicity, cavitation, satellite nodules, smooth border, peripheral location, and subpleural rind.
• Key PET/CT features include low-level metabolism and lack of FDG-avid draining lymph nodes.
KeywordsMultidetector computed tomography PET-CT scan Multiple pulmonary nodules Rheumatoid arthritis Rheumatoid nodule
Cyclic citrullinated peptide
Diffusing capacity for carbon monoxide
Forced expiratory volume in 1 s
Forced vital capacity
Ground glass opacity
High-resolution computed tomography
Positron emission tomography
Pulmonary function test
Total lung capacity
The authors state that this work has not received any funding.
Compliance with ethical standards
The scientific guarantor of this publication is Dr. Jay H. Ryu.
Conflict of interest
Dr. Johnson has received research funding from Pfizer which is not relevant to this work. None of the additional co-authors have relevant disclosures.
Statistics and biometry
Mr. Paul A. Decker kindly provided statistical advice for this manuscript.
The study was approved by the Mayo Clinic Institutional Review Board (IRB16-006571). According to Mayo Clinic institutional policy, patient information may be used for research purposes only with prior patient consent.
Institutional Review Board approval was obtained by the Mayo Clinic Institutional Review Board (IRB16-006571).
Study subjects or cohorts overlap
None of the study subjects or cohorts have been previously reported except for abstract presentation at the American Thoracic Society International Conference 2017.
• Case-control study
• Performed at one institution
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