Clinical Course and Changes in High-Resolution Computed Tomography Findings in Patients with Idiopathic Pulmonary Fibrosis without Honeycombing

Abstract

Some patients with idiopathic pulmonary fibrosis (IPF) do not have honeycombing on high-resolution computed tomography (HRCT) at their initial evaluation. The clinical course and sequential changes in HRCT findings in these patients are not fully understood. We reviewed the cases of 43 patients with IPF without honeycombing on initial HRCT from institutions throughout Japan. All patients were diagnosed with IPF based on a surgical lung biopsy. Multidisciplinary discussions were held five times between 2011 and 2014, to exclude alternative etiologies. We evaluated the sequential changes in HRCT findings in 30 patients with IPF. We classified these 30 patients into three groups based on their HRCT patterns and clarified the clinical characteristics and prognosis among the groups. The patterns of all 30 patients on initial HRCT corresponded to a possible usual interstitial pneumonia (UIP) pattern which was described in the 2011 International Statement. On long-term follow-up (71.0±38.7 standard deviation [SD] months), honeycombing was seen in 16 patients (53%, the HoneyCo group); traction bronchiectasis or cysts without honeycombing was observed in 12 patients (40%, the NoHoneyCo group), and two patients showed no interval change (7%, the NoChange group) on HRCT. The mean survival periods of the HoneyCo and NoHoneyCo groups were 67.1 and 61.2 months, respectively (p = 0.76). There are some patients with IPF whose conditions chronically progress without honeycombing on HRCT. The appearance of honeycombing on HRCT during the follow-up might not be related to prognosis.

Fig 1. Establishing the diagnosis of idiopathic pulmonary fibrosis (IPF) by multidisciplinary discussions.

Fig 2. HRCT images of two patients with representative HRCT scans, showing reticular abnormalities and/or subpleural irregularities without honeycombing.

Fig 3. Representative HRCT scans from the three patient groups.

HoneyCo: Honeycombing became evident on HRCT scan. NoHoneyCo: Traction bronchiectasis or cysts became evident on HRCT scan. NoChange: No significant change in HRCT findings.

Fig 4. Kaplan-Meier survival curves where honeycombing appeared on subsequent HRCT scans after initial evaluation (n = 16, blue line, the HoneyCo group), patients in whom honeycombing was not seen but traction bronchiectasis or cysts appeared on subsequent computed tomography scans after initial evaluation (n = 12, green line, the NoHoneyCo group), and patients with no change in HRCT findings after long-term follow-up (n = 2, yellow line, the NoChange group).