Our patient is a 58-year-old Caucasian male referred initially to the pulmonary clinic for an abnormal high resolution computed tomography (HRCT) of the chest (Figure 1) showing ground glass opacities (GGOs), thickening of the interlobular septa primarily in the bases with minimal honeycombing, mediastinal adenopathies, and small bilateral pleural effusions. He had complaints of progressive shortness of breath and an unproductive cough. Medical history was relevant for 31-pack-year smoking history, asbestos exposure, uncontrolled Diabetes Mellitus type II, and obesity. His oxygen saturation was 93% on room air. Lung auscultation revealed bibasilar crackles with poor air entry but no clubbing or cyanosis. Pulmonary function test demonstrated an obstructive lung disease with mildly decreased forced vital capacity (FVC) at 76% and forced expiratory volume in one second (FEV1) at 70%, borderline FEV1/FVC ratio at 72%, and excellent effort. Lung volumes also revealed a restrictive lung disease with moderately decreased total lung capacity (TLC) at 64%. Finally, the diffusion capacity of carbon monoxide (DLco) was severely reduced at 44%.
The initial outpatient workup included a complete blood count (CBC), comprehensive metabolic panel (CMP), erythrocyte sedimentation rate (ESR), N-terminal probrain natriuretic peptide (NT-proBNP), urinalysis, lactate dehydrogenase (LDH), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), creatine kinase (CK), angiotensin converting enzyme (ACE) level, antineutrophil cytoplasmic antibodies (ANCA), rheumatoid factor (RF), anti-cyclic citrullinated peptide immunoglobulin G (Anti-CCP), histoplasmosis antibodies, human leukocyte antigen B27 (HLA-B27), aspergillus galactomannan antigen, interferon-gamma release assay for tuberculosis, anti-SCL-70 antibody, beta D-glucan, and antinuclear antibodies (ANA). All were negative except a borderline nonspecific elevation in ACE, LDH, and CK levels and positive ANCA antibodies.
To address the interstitial lung disease pattern, a video-assisted thoracoscopic surgery (VATS) lung biopsy was performed. Right lower and right upper lobe wedge excisions revealed classic desquamative interstitial pneumonia, along with foci of respiratory bronchiolitis interstitial pneumonia, mild interstitial fibrosis, and emphysematous changes (Figures 2 and 3).
The patient's history of lifelong smoking along with asbestos exposure likely contributed to these histological changes and DIP diagnosis.
To treat DIP, he was started on a tapered dose of glucocorticoids (starting at 40 mg of prednisone) along with nicotine replacement therapy for smoking cessation. Over a 7-month treatment course, the prednisone dose was lowered to 10mg with improvement in his dyspnea and cough. With assistance from the nicotine replacement, the patient successfully quit smoking for 6 months. Repeat CT images showed improvement in GGOs and resolution of prior small pleural effusions.
After 7 months of DIP treatment and with minimal respiratory symptoms, he restarted smoking one pack of cigarettes a day. Six weeks after restarting smoking, respiratory issues quickly developed, and he required hospitalization for acute hypoxemic respiratory failure. Upon admission the patient was tachypneic with labored breathing, worsening bibasilar crackles, decreased air entry, and an unproductive cough. Given his presentation and dropping oxygen saturation to 84% on room air, he was given 100% FiO2 (fraction of inspired oxygen) by nonrebreather mask.
After discussing treatment options for respiratory failure, the patient refused intubation and mechanical ventilation with complete understanding that his condition could be life-threatening. His breathing was therefore supported with alternating 100% FiO2 by nonrebreather mask and noninvasive ventilator support to maintain oxygen saturation above 90%.
A chest X-ray (Figure 4) and a chest CT angiogram (Figure 5) were ordered. No pulmonary emboli were found. However, imaging did show significant worsening bilateral GGOs, bibasilar consolidations, mediastinal adenopathies, and a new moderate right pleural effusion. The patient was started on broad spectrum antibiotics with vancomycin, piperacillin/tazobactam, and azithromycin. Laboratory workup was unremarkable for infection however. White blood cell count was slightly elevated at 12,600 without a left shift. Procalcitonin level was borderline at 0.14 ng/mL, C-reactive protein was elevated initially but then normalized, and the patient was afebrile at 98.4 Fahrenheit. NT-proBNP was normal which excluded congestive heart failure as a cause for the pleural effusion and GGOs. Repeated arterial blood gas measurements displayed no abnormalities in pH or carbon dioxide levels despite his labored breathing.
Additional negative tests included respiratory polymerase chain reaction viral panel, fungal serology, blood cultures, sputum acid-fast bacilli testing, urine streptococcus, and legionella. Sputum fungal and bacterial cultures grew Candida dubliniensis and Pseudomonas fluorescens. Although, these organisms are not generally considered pathogens in humans unless severely immunocompromised and have been found in normal oral flora.
To further investigate a cause for the acute decompensation, the patient was offered a bronchoscopy and thoracentesis for mediastinal sampling and pleural effusion, respectively. After an extensive discussion, he refused all invasive diagnostic procedures.
Four days passed after being given broad spectrum antibiotics and no improvement was observed. Repeat imaging showed a persistence of bilateral interstitial opacities and pleural effusion. His oxygen saturation level still required 100% FiO2 supplementation to maintain above 90%. Because initial workup for the acute respiratory failure was inconclusive, less common etiologies were considered including DIP exacerbation.
On the fourth hospitalization day, treatment for possible DIP exacerbation was initiated and antibiotics were stopped. He was given 40 mg methylprednisolone every 8 hours. Within hours, his shortness of breath and oxygen saturation drastically improved. All respiratory symptoms dissipated, and he was stable to be treated as an outpatient after 48 hours of starting treatment. His discharge plan included oxygen support by nasal cannula and oral prednisone. He agreed to a smoking cessation plan with nicotine patches.
Ten days after discharge, an office-visit chest X-ray (Figure 6) showed complete resolution of the pleural effusion and bilateral interstitial and airspace diseases markedly improved. His oxygen saturation climbed to 96% on room air indicating supplemental oxygen was no longer needed.