Lung nodules at AAV diagnosis may point to more relapses
Study finds those with nodules have more related relapses
Written by |
People with ANCA-associated vasculitis (AAV) who have pulmonary nodules ( rounded masses of tissue in the lungs) at diagnosis are more likely to experience relapses involving these nodules than those without, a study found.
Fewer nodules with a hollow center, a smaller nodule cavity, and a lower ratio of dead tissue in the nodule were each linked to higher rates of complete nodule regression on CT scans after six months of treatment, data showed.
“To our knowledge, this study represents the most comprehensive radiological [imaging] assessment conducted to date on this subject,” the researchers wrote. “These exploratory findings require … validation [in studies following patients over time and] using standardized CT protocols.”
The study, “The effect of pulmonary nodule presence on disease severity and course in ANCA-associated vasculitis: a multicenter cohort study,” was published in BMC Pulmonary Medicine.
AAV is a group of rare conditions in which abnormal immune responses cause inflammation and damage in small blood vessels throughout the body, most commonly affecting the kidneys and lungs. Lung abnormalities on chest CT scans are reported in up to 77% of patients.
Nodules common in AAV
Pulmonary nodules are common in AAV. Many are granulomas (small clusters of immune cells), but they can also be caused by tissue scarring or appear on scans as nodule-like structures but represent localized bleeding.
Previous research has linked cavitary pulmonary nodules, or those with a hollow center, to a higher risk of relapse, when disease activity and/or symptoms return after remission. However, “there is a lack of sufficient studies investigating the impact of the characteristic features of pulmonary nodules on the disease course,” the researchers wrote.
With this in mind, the team reviewed the medical records of 342 adults with AAV — 100 with pulmonary nodules and 242 without nodules at AAV diagnosis — followed at seven centers in Turkey. Of those with nodules, 49 had non-cavitary nodules, and 51 had cavitary nodules.
Most participants had granulomatosis with polyangiitis (GPA), a type of AAV. Age at disease onset was significantly older in the nodule-positive group (52.6 vs. 47.5). All received glucocorticoids as AAV treatment, while the majority in both groups were treated with cyclophosphamide as the induction (first) therapy.
Patients presenting with pulmonary nodules at diagnosis had significantly lower protein levels in the urine, indicating better kidney function. The nodule-positive group was also significantly more likely to have excess fluid around the lungs (20% vs. 10.7%), and this result was mainly driven by the significantly higher rate of excess fluid in patients with cavitary nodules (27.5%).
Imaging features of all nodules in the 108 participants who had nodules at diagnosis or during relapse were analyzed. The researchers found that cavitary nodules were more common than non-cavitary nodules (51.8%), and that non-cavitary nodules were also seen in 34.2% of those with cavitary nodules. The largest cavitary nodule was twice as large as the largest non-cavitary nodule (36 vs. 18 mm).
Also, non-cavitary nodules were located mainly beneath the lung lining (47.2%), while cavitary nodules were located primarily around the airways and blood vessels (66.1%).
Larger cavity nodule diameters and thicker cavitary walls were significantly associated with higher blood CRP levels, a marker of body-wide inflammation. This “may indicate that cavity size reflects the current inflammatory burden,” the team wrote.
Available data of six-month follow-up CT scans from 73 of the 108 patients showed that 21.9% achieved complete regression (nodules disappeared), and 65.8% experienced partial regression.
Final follow-up scans, taken at a median of 39 months (slightly more than three years) after diagnosis, showed complete regression in 71.8% and partial regression in 23.1%. Regression rates were similar between cavitary and non-cavitary nodules at both time points.
Further statistical analyses demonstrated that a higher ratio of dead tissue inside the nodule cavity was significantly associated with a lower chance of regression at both time points. “Such irreversible structural damage may partly explain the reduced likelihood of complete radiological regression,” the researchers wrote.
Also, fewer cavitary nodules and smaller cavity diameters were each significantly associated with a higher chance of complete regression.
Overall, remission within six months was comparable between the patients with nodules and those without. More than one-third of patients (39%) experienced a relapse, with similar rates between those with and without nodules. Still, relapses involving pulmonary nodules were about five times more frequent in patients with nodules at diagnosis than in those without (15.3% vs. 3.4%).
The findings highlight that patients with nodules at diagnosis have a “significantly higher risk of pulmonary nodule relapse,” while overall relapse rates did not differ between groups, the researchers wrote.
Findings on cavity size, wall thickness, and necrosis ratio should be considered exploratory, and require confirmation in studies following patients over time and “using standardized CT protocols, validated volumetric measurements and [disease-associated] correlation,” the researchers concluded.
Leave a comment
Fill in the required fields to post. Your email address will not be published.