Rheumatoid arthritis (RA) is often associated with interstitial lung fibrosis, but in most cases the manifestation is not detected in chest radiographies. Researchers at the Fornaroli Hospital Magenta, in Italy, recently revealed that ultrasound ecography likely serves as a better diagnostic tool and can increase identification of RA patients with interstitial pneumonias.
The study, “Ultrasound in Rheumatologic Interstitial Lung Disease: A Case Report of Nonspecific Interstitial Pneumonia in Rheumatoid Arthritis” and published in Case Reports in Rheumatology, reports on a particular case involving ultrasound ecographic follow-up.
RA is a chronic inflammatory disease that affects the joints primarily, but can result in extra-articular manifestations such as interstitial pneumonia and fibrosis. Approximately 40 percent of RA patients are reported to have interstitial fibrosis, but their chest radiography and high-resolution computed tomography (HRCT) scans only detect evidence of the manifestations in 5 percent and 30-40 percent of cases respectively.
Although RA is most commonly associated with usual interstitial pneumonia (UIP), nonspecific interstitial pneumonia (NSIP) can also be observed in RA patients. In some cases, NSIP can even anticipate RA joint symptoms.
Currently, chest HRCT is the gold standard technique for the diagnosis of pulmonary fibrosis. But recent reports show that ultrasound ecographies can also detect fibrosis through the presence of ultrasound lung comets (ULCs), which are multiple comet tails fanning out from the lung surface. The structures positively correlate with the scores of pulmonary fibrosis detected by HRCT, suggesting that ultrasound ecographies may be a simpler and radiation free alternative to HRCT for lung fibrosis diagnosis.
The research case revolved around a 54-year-old male who was admitted to the hospital for interstitial lung disease of uncertain origin. The patient had fever, dry cough, and chest pain at the time of admission, and both chest X-ray and CT revealed interstitial fibrosis. Rheumatoid factor and anti-cyclic citrullinated peptide (CCP) antibodies, which increase the risk of RA patients developing interstitial lung diseases, were elevated. The observations, combined with lung CT and positron emission tomography CT (PET/CT) observations, led researchers to hypothesize rheumatologic rather than infective interstitial lung disease. Ultrasound of the lung also revealed the presence of ULCs.
Together, the results led to the diagnosis of NSIP in RA seropositive for rheumatoid factor. The patient started on immunosuppressive therapy with cyclophosphamide, commonly used in RA patients. One month later, HRCT showed a significant improvement of interstitial lung disease. The same was observed with ultrasound; the therapy completely resolved ULCs.
These observations suggest that lung ultrasound is a valuable tool for interstitial lung disease detection, diagnosis and prognosis.