Case Study and Clinical Highlight: Diagnosis of Pulmonary Involvement in Systemic Sclerosis

A 60-year-old female patient presents to the outpatient clinic for evaluation of her systemic sclerosis (SSc). She has been prescribed methotrexate in the past, but she has been non-compliant with medication and  follow-up visits.  She complains of new-onset progressive shortness of breath, first noted 3 weeks ago when she ran to catch a bus. She was evaluated at an urgent care clinic, where a chest radiograph was performed and blood samples were taken. She was subsequently sent home and told to follow up with her doctor.

She reports chronic non-productive cough on review of systems. She denies syncope, productive cough, acid reflux symptoms, hemoptysis, chest pain, ankle swelling, or new joint pain.  She denies history of cigarette smoking or exposure to new medications, fumes, or chemicals.

On physical examination, the patient is afebrile, normotensive, and breathing comfortably without tachypnea. Diffuse skin thickening, perioral skin tightening, calcinosis cutis of the hands, and scattered areas of cutaneous hyperpigmentation of the distal upper extremities are noted. Auscultation of the chest reveals bibasilar, dry inspiratory crackles, while auscultation of the heart is within normal limits. There is no evidence of peripheral edema or clubbing.

Review of the chest radiograph obtained at the urgent care center 2 weeks ago shows scattered symmetric ground-glass opacities. There is no cardiomegaly, pleural effusion, air bronchograms, lobar consolidations, or masses noted on the radiograph.  Complete blood count (CBC), basic metabolic panel (BMP), D-dimer, and brain natriuretic peptide (BNP) levels are within normal limits.

High on the differential diagnosis is SSc lung involvement, including interstitial lung disease (ILD) and pulmonary vascular disease, which may occur separately or together.  SSc-associated ILD commonly presents with the subacute onset of dyspnea on exertion, sometimes associated with a nonproductive cough. 

Radiographs obtained at the urgent care clinic appear to have some classic features of SSc-associated ILD: symmetric reticular or ground-glass opacities.  

SSc-associated ILD usually seen at the base of the lungs. Assessment of the radiograph for hazy or reticular opacities in the lower lobes, to evaluate for ILD, or enlarged pulmonary arteries, to evaluate for pulmonary hypertension, is difficult. 

Chest radiography is a relatively insensitive tool for the detection of early ILD, as it has a low sensitivity and specificity for detecting parenchymal involvement. In contrast, chest radiography has good specificity in identifying pulmonary hypertension (PH), by detection of enlargement of right pulmonary artery, loss of peripheral vasculature and filling of the retrosternal space by the hypertrophic right ventricle.

High-resolution computed tomography (HRCT) is ordered to evaluate the structural abnormalities associated with ILD and to further examine the nature and location of the ground-glass opacities detected on chest radiograph.

Next: Diagnostic Imaging and Pulmonary Function Testing