Pulmonary fibrosis and solitary pulmonary nodule in hidden rheumatoid arthritis

History of present illness

A 78-year-old Caucasian man underwent a visit at the outpatient pulmonology clinic complaining of persistent dry cough and dyspnea during moderate exertion in the last year. On the suggestion of his general practitioner, he had previously received a chest radiograph, which revealed an irregular reticulation in the lower zones, suspicious for interstitial lung disease (ILD).

Past medical history

The patient was a never-smoker and previously an amusement park employee, with a family history negative for pulmonary disease. He declared to have an unspecified thyroid disease not requiring medical treatment, whereas he was on proton pump inhibitor therapy for gastroesophageal reflux disease and a sartan for hypertension. He denied home exposure to mold and parrots during the past few years. He reported no symptoms correlated with obstructive sleep apnea syndrome or asthma-related symptoms during his lifetime. Eight years earlier, he underwent radical bowel surgery for rectal cancer that had not required chemotherapy treatment.

Subsequently, he scrupulously complied with scheduled cancer follow-ups with no evidence of disease recurrence or extension.

Physical examination and early clinical findings

During the physical examination, the patient was alert and cooperative, apyretic, and eupneic at rest (respiratory rate 14 breaths/minute). Oxygen saturation (SpO ₂ ) was 96% on room air, heart rate was 78 beats/min, and blood pressure was 120/65 mmHg. There were no current or previous signs and symptoms suggestive of a connective tissue disease (CTD) or systemic vasculitis. On chest auscultation, vesicular murmur appeared reduced in all lung areas with the presence of Velcro-like crackles at the bases bilaterally. He underwent a high-resolution computed tomography (HRCT) scan of the chest, which confirmed an ILD with reticulations, subpleural and basal honeycombing, and traction bronchiectasis, in the absence of features inconsistent with usual interstitial pneumonia (UIP) pattern ( Figs. 12.1 and 12.2 ).

Pulmonary function tests (PFTs) revealed a restrictive ventilatory defect with a decreased diffusing capacity of the lung for carbon monoxide (DLCO): forced vital capacity (FVC) was 72% predicted, total lung capacity (TLC) 80% predicted, DLCO 55% predicted. He also performed a 6-minute walk test with no significant oxygen drop (distance covered 400 m, test not interrupted early). During the second appointment, the screening for autoimmunity showed antinuclear antibodies (ANAs) positivity (titer 1:160) with negative extractable nuclear antigen (ENA) typing, negative myositis pattern, and no positive value was found for rheumatoid factor (RF), anti-cyclic citrullinated peptide antibodies (ACPAs), cytoplasmic antineutrophil cytoplasmic antibodies (c-ANCA), and perinuclear antineutrophil cytoplasmic antibodies (p-ANCA); inflammatory indexes and markers of acute viral hepatitis (hepatitis B and C virus) were also negative. Echocardiogram showed normal right heart sections, minimal tricuspid regurgitation, and preserved systolic function (left ventricular ejection fraction [LVEF] 65%).

Clinical course

A multidisciplinary team (MDT) reviewed lung CT scan images and confirmed the presence of a definite usual interstitial pneumonia (UIP) pattern. Based on clinical and radiological data, in the absence of evident underlying causes, a highly confident diagnosis of idiopathic pulmonary fibrosis (IPF) was made. Subsequently, the patient started an antifibrotic therapy with nintedanib, initially 150 mg twice daily for about 1 year, then 100 mg twice daily due to the occurrence of persistent gastrointestinal side effects. The patient remained stable on clinical, radiological, and functional aspects for the following 2 years. Then, a new chest CT scan performed for morphological reevaluation of the lung parenchyma revealed a solid nodule approximately 12 mm in diameter in the basal segment of the right lower lobe. There were no enlarged mediastinal or axillary lymph nodes. So, the case was discussed again by the MDT, including a thoracic surgeon with expertise in ILD, and a positron emission tomography (PET)-CT scan was proposed to add more information about the nodule. On the PET-CT scan, the lung lesion showed increased volume and mild metabolic activity, rising the suspicion of lung cancer at stage I ( Fig. 12.3 ).