SYSTEMIC SCLEROSIS (SCLERODERMA)
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.
