Sarcoidosis

What Sarcoidosis Is

Sarcoidosis is one of the more frequently recognized causes of granulomatous interstitial lung disease, and it is worth understanding as its own distinct entity rather than a variant of idiopathic pulmonary fibrosis or another fibrotic ILD subtype, since its causes, expected course, and treatment approach differ considerably.

Pulmonary vs. Extrapulmonary Presentation

Pulmonary involvement, whether lymph node enlargement, lung tissue involvement, or both, is the most common presentation of sarcoidosis. Extrapulmonary involvement is also common enough that it is worth understanding the major patterns rather than treating it as a rare curiosity.

Where Sarcoidosis Can Show Up

Lungs and Chest Lymph Nodes

The most common site of involvement, ranging from lymph node enlargement alone to lung tissue involvement and, less commonly, established scarring.

Skin

Nodules, raised plaques, or, in the specific pattern called lupus pernio, discolored plaques on the nose, cheeks, and ears. Erythema nodosum, tender red shin nodules, is a related but distinct reactive skin finding.

Eyes

Uveitis, inflammation inside the eye, is one of the more common extrapulmonary manifestations and is a reason ophthalmologic evaluation is a standard part of a thorough workup.

Heart

Cardiac sarcoidosis can cause conduction abnormalities, arrhythmias, or heart failure, and is taken seriously as a recognized cause of sudden cardiac death.

Lymph Nodes Elsewhere

Enlarged, usually painless lymph nodes can appear outside the chest as well, such as in the neck or under the arms.

Nervous System, Liver, and Other Organs

Less common but recognized sites of involvement, each with its own evaluation when clinically suspected.

Chest X-Ray Staging: The Scadding System

Pulmonary sarcoidosis is often described using a chest X-ray staging system, sometimes called Scadding staging, that has been in clinical use for decades. It remains a useful shorthand for describing the imaging pattern, and it is still referenced in current guidelines, even though high-resolution CT can add further detail in individual cases.

Stage 0

Normal chest X-ray

No visible chest involvement on a plain radiograph, though extrapulmonary disease can still be present.

Stage I

Bilateral hilar lymphadenopathy alone

Lymph node enlargement without lung tissue involvement; the most common pattern at diagnosis and associated with a high likelihood of spontaneous improvement.

Stage II

Hilar lymphadenopathy plus lung infiltrates

Both lymph node enlargement and involvement of the lung tissue itself are present.

Stage III

Lung infiltrates without lymphadenopathy

Pulmonary involvement persists while the lymph node enlargement has resolved or diminished.

Stage IV

Pulmonary fibrosis

Established lung scarring; associated with the lowest likelihood of spontaneous improvement and the greatest risk of long-term functional impairment.

These stages describe the chest X-ray pattern at a given point in time, not a strict severity ranking or a required progression. Many people are diagnosed at stage I and never advance further, and a person can present at any stage.

How Sarcoidosis Is Diagnosed

There is no single test that confirms sarcoidosis on its own. Diagnosis is built on three elements together: a clinical and imaging picture consistent with sarcoidosis, biopsy evidence of the characteristic granulomas, and exclusion of other conditions that can look similar.

The Diagnostic Pathway

1. 01→Clinical SuspicionSymptoms, an incidental imaging finding, or a specific pattern such as Löfgren syndrome raises concern for sarcoidosis.↓
2. 02→Chest ImagingA chest X-ray establishes the Scadding stage; high-resolution CT is sometimes added for a more detailed look or when the presentation is atypical.↓
3. 03Excluding Other CausesInfections such as tuberculosis or fungal disease, other granulomatous conditions, and relevant occupational exposures are ruled out, since these can mimic sarcoidosis both clinically and on tissue sampling.↓
4. 04→Tissue BiopsyA biopsy, often obtained during bronchoscopy with sampling of an enlarged chest lymph node, or from an accessible extrapulmonary site such as a skin lesion, looks for non-caseating granulomas, granulomas without the central tissue death seen in some infections.↓
5. 05→Extrapulmonary EvaluationA baseline EKG, an ophthalmologic exam, and additional organ-specific testing are performed as clinically indicated, since some extrapulmonary involvement can be present without obvious symptoms.↓
6. 06Putting It TogetherThe diagnosis is confirmed when the clinical and imaging picture, biopsy findings, and exclusion of alternative diagnoses are all consistent with sarcoidosis.

High-resolution CT imaging can add detail beyond a standard chest X-ray, particularly when the presentation is atypical or fibrosis is a concern, and bronchoscopy, often with endobronchial ultrasound-guided sampling of an enlarged lymph node, is the most common way a tissue diagnosis is obtained when the chest is the most accessible site of disease.

Pulmonary Function Testing and Monitoring

Pulmonary function testing, including DLCO, is used both around the time of diagnosis and on an ongoing basis to track how sarcoidosis is affecting lung function. A restrictive pattern, reduced lung volumes, or a reduced DLCO can develop as pulmonary involvement progresses, and periodic testing helps distinguish stable disease from disease that is meaningfully worsening, which matters for treatment decisions.

Cardiac and Ocular Sarcoidosis Deserve Particular Attention

Because cardiac sarcoidosis is a recognized cause of sudden cardiac death and ocular sarcoidosis can threaten vision if untreated, these two organ systems are evaluated proactively rather than only when symptoms are already present. A baseline EKG and an eye exam are standard parts of an initial sarcoidosis evaluation for this reason, and further cardiac imaging, such as a cardiac MRI or PET scan, is pursued when cardiac involvement is suspected. Advanced pulmonary sarcoidosis can also lead to pulmonary hypertension, a complication that is evaluated and managed alongside a patient’s broader pulmonary and cardiac care.

Treatment: When and How

Treatment decisions in sarcoidosis start with an honest assessment of whether treatment is actually needed, since a substantial share of pulmonary sarcoidosis, particularly at earlier chest X-ray stages, improves or stays stable without any medication at all.

Observation. For asymptomatic or mildly symptomatic disease, active monitoring with periodic clinical review, imaging, and pulmonary function testing is often the appropriate starting approach rather than immediate treatment.

Corticosteroids. When treatment is needed, whether because of progressive symptoms, declining lung function, or involvement of an organ such as the heart or eyes where the stakes of ongoing inflammation are higher, oral corticosteroids are the first-line therapy. They are effective at suppressing the granulomatous inflammation driving disease, though prolonged use carries real side effects, so physicians generally aim for the lowest effective dose with a gradual taper once disease is controlled.

Corticosteroid-sparing agents. When corticosteroids alone are not adequately controlling disease, would be needed at doses associated with too much toxicity, or cannot be tolerated, immunosuppressant medications such as methotrexate or azathioprine are added or substituted. Biologic therapy, most studied in the form of infliximab, is reserved for disease that remains refractory despite these steps.

Organ-specific care. Cardiac, ocular, and neurologic sarcoidosis are generally co-managed with the relevant specialist, since each of these organ systems has its own monitoring approach and treatment nuances beyond what a pulmonologist manages alone.

Living With Sarcoidosis

Because the course of sarcoidosis varies so much between individuals, from disease that resolves within a couple of years to disease that follows a more chronic course, ongoing follow-up is generally recommended even for people who are not on treatment. This typically includes periodic clinical review, imaging, and pulmonary function testing, with the specific interval tailored to how a person’s disease has behaved so far.

Persistent fatigue is common and deserves to be addressed directly with a physician rather than dismissed as an inevitable part of the disease, and new or changing symptoms, particularly cardiac symptoms such as palpitations or fainting, or new visual symptoms, warrant prompt evaluation rather than being attributed automatically to already-known sarcoidosis.

Getting an Accurate Diagnosis

Because sarcoidosis can present in so many different ways, and because a similar-looking presentation can sometimes be caused by an infection or another condition that requires very different treatment, a thorough evaluation matters, particularly before starting corticosteroids or another immune-modulating medication.

For patients in the North Dallas-Fort Worth area, the pulmonary team at VitalAir Sleep & Lung Center in Frisco, Texas offers pulmonary function testing and evaluation for unexplained shortness of breath, cough, or an abnormal chest imaging finding, which can be an appropriate starting point when sarcoidosis or another form of interstitial lung disease is a consideration.