Article Update

Sunday, March 7, 2021



Systemic sclerosis (SSc) is a systemic autoimmune disorder that clinically involves the skin, gastrointestinal tract, musculoskeletal system, kidneys, heart, and lungs. Most patients are women in their fourth and fifth decades of life. Common presenting complaints include Raynaud phenomenon; tightening of the skin of the face, upper extremities, and thorax; dysphagia; cough; and dyspnea. A variety of clinical SSc subtypes exist; diffuse cutaneous, limited, and sine scleroderma are all defined by specific patterns of skin involvement. Some pulmonary abnormality can be identified in almost all patients, and certain phenotypes are more commonly associated with specific pulmonary complications than others. However, all known pulmonary manifestations have been described in each of the SSc subtypes, and one should not exclude a particular pulmonary disorder based solely on a clinical or serologic scleroderma phenotype.

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A large number of pulmonary manifestations are recognized, with interstitial lung disease (ILD) and pulmonary hypertension being the most common as well as the leading causes of death. Chronic aspiration caused by esophageal dysmotility, airways disease, neuromuscular weakness, physiologic restriction secondary to a hide-bound chest, pleural effusions, pneumothorax, and lung cancer all cause clinically significant disease and occur commonly enough to be considered in SSc patients with respiratory symptoms. As in all connective tissue diseases (CTDs) the presence of infection or drug reaction should be an initial consideration in all patients with new or worsening respiratory signs or symptoms. Pulmonary hypertension is the single leading cause of mortality. Although a pulmonary arteriopathy similar to that seen in idiopathic pulmonary arterial hypertension (IPAH) is the dominant mechanism, left ventricular diastolic dysfunction, chronic thromboembolic disease (generally associated with the presence of antiphospholipid antibodies), and loss of vascular bed as a consequence of ILD can all contribute. Dyspnea on exertion is the presenting symptom, and syncope is a poor prognostic sign. Chest imaging features on high- resolution computed tomography (HRCT) may give hints of pulmonary hypertension with the presence of pericardial disease, an enlarged main pulmonary artery, and mosaic attenuation. Given its ease of use, resting transthoracic echocardiography (TTE), with estimation of right ventricular systolic pressure (RVSP), is generally the first step in diagnosis; however, it regularly both overestimates and underestimates the presence or absence as well as the degree of pulmonary hypertension. When pulmonary hypertension is considered, right-sided heart catheterization remains the gold standard for diagnosis. With currently available treatments, survival rates at 1 year of 81% and at 2 years of 71% can be expected.

ILD is the most common pulmonary manifestation, with clinically significant disease observed in more than one-third of patients. Neither the extent nor severity of the skin disease correlates with the presence or severity of the pulmonary disease, and although it is seen more commonly in diffuse cutaneous disease (dcSSc), it also occurs in limited cutaneous  disease (lcSSc) as well as in those without any skin involvement. Abnormalities on HRCT consistent with ILD are seen in a large majority of patients, and abnormal pulmonary physiology is reported in 45% to 100%, with a restrictive defect and a decreased diffusing capacity being the common findings. Because the most rapid decline in vital capacity occurs in the first 4 years of disease, those with a lower baseline forced vital capacity (FVC) are at higher risk of progressive lung disease. Although an isolated reduction in DLCO (diffusing capacity for carbon monoxide) is an early and sensitive sign of SSc-ILD, this finding should also prompt evaluation for PH. Although bronchoalveolar lavage has been used to identify the presence of lung disease in SSc, HRCT has been found to be more sensitive. In contrast to RA and more in common with the other CTDs, nonspecific interstitial pneumonia (NSIP) is the most prevalent pathologic pattern seen on surgical lung biopsy. Treatment of patients with Ssc-ILD with cyclophosphamide has been shown to be associated with improvements in FVC, skin score, and quality of life.

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