A 74-year-old man was referred to our hospital with abnormal chest X-ray findings in February 2015. He complained of dry cough, dyspnea on exertion (DOE) of modified Medical Research Council (mMRC) grade 1, and intermittent arthralgia. Initial significant findings were fine crackles in bilateral lower lung fields and tenderness of the metacarpophalangeal joint of the left second digit. Initial laboratory findings were as follows: rheumatoid factor 7.2 IU/ml, anti-cyclic citrullinated peptide antigen 818.9 IU/mL, and erythrocyte sedimentation rate (1 hour) 92 mm. Initial high-resolution computed tomography (HRCT) images showed typical UIP pattern with basal and subpleural lung dominant reticular opacities, interlobular septal thickness associated with honeycombing and traction bronchiectasis. Since the morphologic pattern showed UIP with no apparent cause, the diagnosis was IPF.
His symptoms gradually worsened over 2 years until January 2017; his dry cough increased, and DOE gradually worsened to mMRC grade 2. Chest HRCT images showed extended reticulation (Fig. 1B).
Pulmonary function test findings, especially FVC, also declined (Fig. 2). In February 2017, bronchoalveolar lavage (BAL) and transbronchial lung biopsy (TBLB) were performed. BALF cytology showed total cell counts of 2.71 x 105/mL, lymphocytes of 12%, and a CD4/CD8 ratio of 0.4. Histopathology showed old fibrosis and aggregated alveolar walls accompanying fibroblastic foci. At that time he had no arthralgia. Treatment was initiated with nintedanib 300 mg/day. It was generally well tolerated except for slight diarrhea. His dry cough improved gradually and diminished 8 months after he started treatment. Pulmonary function testing also improved; the gradual FVC decline in February recovered 60 mL 3 months after treatment initiation, followed by milder decline. FVC decreased by 490 ml 13 months after the initial visit (-12.6%/13 months) and by 90 ml after 6 months of treatment (-2.6%/6 months) (Fig. 2).
In October 2017, his metacarpophalangeal joint of the left second digit developed swelling. At this time, he met the criteria of RA with a DAS 28 score of 3.61, showing moderate disease activity.