Evolution of Pulmonary Involvement in Idiopathic Multicentric Castleman Disease-Not Otherwise Specified

Previous studies about multicentric Castleman disease-associated pulmonary manifestations have been limited by small cohorts and not following the Castleman Disease Collaborative Network classification criteria of multicentric Castleman disease. The pulmonary manifestations in idiopathic multicentric Castleman disease-not otherwise specified (iMCD-NOS), a distinct clinical phenotype in the classification criteria, have not been reported.Which pulmonary abnormalities in iMCD-NOS are advanced manifestations and which are reversible after effective treatment?Patients diagnosed with iMCD-NOS with pulmonary involvement were enrolled. The baseline CT scan was evaluated for the presence and anatomic locations of pulmonary abnormalities. Patients were further divided into different subgroups according to baseline CT scan manifestations. Follow-up CT scan was reviewed to assess the changes in pulmonary lesions among patients without and with treatment.Of 162 patients with iMCD-NOS, 58 individuals (35.8%) with pulmonary involvement were identified. Pulmonary manifestations included nodules (96.6%), cysts (65.5%), consolidation (22.4%), interstitial thickening (50.0%-87.9%), and ground-glass opacities (55.2%). Patients (n = 58) were further classified into nodule (n = 15), cyst (n = 33), and consolidation (n = 10) subgroups. Patients in the consolidation (median, 67 months) and cyst (median, 23 months) subgroups had a longer duration of symptoms before the baseline CT examination than those in the nodule subgroup (median, 12 months) (P = .016). During follow-up, the evolution of pulmonary lesions from nodules to cysts was observed in two patients without treatment. After treatment, pulmonary lesions, except for cysts, improved in most patients. Moreover, nodules or cysts progressed into consolidation in two patients.Pulmonary involvement is not rare in iMCD-NOS. Chest CT scan examination is very essential in finding potential pulmonary abnormalities. Pulmonary manifestations follow a unique pattern with evolution from nodules to cysts or consolidation, the latter of which can also form in cystic areas. Timely diagnosis of pulmonary involvement is crucial because of possible reversibility after treatment.