HRCT findings in idiopathic pneumonia syndrome with documentation of the disease course

Objective: To analyze extent and patterns of lung involvement in patients with idiopathic pneumonia syndrome (IPS) following allogeneic stem cell transplantation (SCT), and demonstrate their course during therapy.

Methods: 14 consecutive patients (age 29-64 years, mean 46.2 years) who experienced IPS after allogeneic SCT (as defined by current guidelines of NIH) were treated with either steroids (n = 5), or steroids and the TNF-α blocker etanercept in more severe cases (n = 9). CT-scans obtained before, during and after IPS were evaluated retrospectively. Quantification of pulmonary involvement was performed by visual estimation. Surveillance time ranged from 21 to 914 days with a total of 99 CT-scans (2-12 CT-scans per patient) obtained.

Results: IPS was mainly confined to the central lung regions (71%) with a bilateral and symmetric distribution (71%). Ground-glass opacity (93%) was the prominent CT-morphologic correlate, whereas concomitant consolidation of lung areas (noted in 43% of patients at the time of maximum infiltrates) only occurred in severe courses of IPS (p<0.01). Favourable courses (50%) showed an earlier peak with respect to extent and CT-attenuation of IPS infiltrates (p<0.01) followed by a rapid decline (median IPS duration 8 days) whereas a significantly more protracted course was observed in severe (unfavorable) cases (median IPS duration 52 days, p = 0.01). The death rate in the first and the latter groups (all of the severe cases receiving TNF blockage) was 0% and 43%, respectively. Pulmonary sequelae were recorded in almost all patients during follow-up with fibrotic residues.

Conclusion: HRCT-features of IPS are non-specific, but predictable. Response monitoring in IPS can be well accomplished via HRCT and the course of pulmonary infiltrates heralds patient's outcome.