SSc-ILD

Diagnosis

Diagnosis of systemic sclerosis (SSc)¹

Diagnosis of SSc can be obvious in patients with combinations of classic manifestations. However, in some patients, the diagnosis cannot be made clinically, and confirmatory laboratory tests can increase the probability of disease but their absence does not exclude it.¹

The criteria for SSc by the American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) include the following features:¹

• Skin thickening of the fingers of both hands
• Fingertip lesions (ulcers, pitting scars)
• Telangiectasia
• Abnormal nail-fold capillaries (ectatic blood vessels, dropout areas) on capillaroscopy examination (seen with an ophthalmoscope or dissecting microscope)
• Pulmonary arterial hypertension and/or interstitial lung disease
• Raynaud phenomenon
• Systemic sclerosis–related autoantibodies (anticentromere, anti–Scl-70, anti–RNA polymerase III). The most cost-effective way is to test for antinuclear antibodies (ANA), anti-Scl-70 and anticentromere antibodies first. If results are negative, testing for other antibodies should be considered based on clinical manifestations.

Diagnosis of systemic sclerosis associated interstitial lung disease (SSc-ILD)^2-4

High-resolution computed tomography (HRCT) patterns²

HRCT imaging is critical for interstitial lung disease (ILD) detection in SSc patients. The most common histologic pattern seen in SSc-ILD is nonspecific interstitial pneumonia (NSIP). The usual interstitial pneumonia (UIP) pattern is less common.

NSIP pattern: The NSIP pattern is characterized by increased reticular markings, ground glass opacities, and traction bronchiectasis with minimal honeycombing.

UIP pattern: The UIP pattern is predominantly peripheral and bibasilar reticulonodular opacities with honeycombing.

Pulmonary function test (PFT)^3,4

PFTs in patients with SSc-ILD generally demonstrate a restrictive pattern, with reduced forced vital capacity (FVC) and diffusion capacity of the lung for carbon monoxide (DLCO). However, even in patients with clear fibrosis on HRCT, FVC may be normal.³

It is recommended that all newly diagnosed patients with SSc should have baseline PFT, with follow-up testing every 3–6 months for the next 3–5 years. Annual spirometry and diffusion should be done after the 3–5 years with more frequent testing in patients with established ILD. HRCT should be done at baseline and repeated when there is a clinically meaningful decline in pulmonary function or new symptoms that could be attributed to SSc-ILD.⁴