Sarcoidosis (Thoracic Nodes)
Sarcoidosis is a systemic inflammatory disease in which small collections of immune cells, called granulomas, form in various organs—most commonly the lymph nodes inside the chest and the lungs. Enlargement of thoracic lymph nodes (hilar and mediastinal nodes) is one of the most characteristic imaging findings of sarcoidosis and is often discovered incidentally on chest imaging. The condition can range from mild and self-limited to a chronic process with significant lung and systemic involvement. CT and MRI play important roles in identifying typical patterns and guiding further evaluation.
What is it?
Sarcoidosis is a chronic inflammatory disease in which small, organized clusters of immune cells—called granulomas—form in different organs of the body. The lungs and the lymph nodes inside the chest are the most commonly affected areas, but sarcoidosis can also involve the skin, eyes, heart, nervous system, liver, spleen, bones, and other tissues. Why these granulomas form is not fully understood, though current understanding points to an exaggerated immune response in genetically susceptible people, possibly triggered by environmental or infectious factors.
Sarcoidosis is particularly associated with characteristic enlargement of certain thoracic (chest) lymph nodes. The classic imaging pattern is bilateral hilar lymphadenopathy—symmetric enlargement of lymph nodes around the airways at the roots of each lung—often combined with enlarged mediastinal nodes (such as those in the right paratracheal region). This pattern, when present, can strongly suggest sarcoidosis, especially in patients with compatible symptoms or other findings.
A widely used radiographic staging system describes the typical patterns seen with sarcoidosis: stage 0 (normal imaging), stage I (only enlarged thoracic lymph nodes), stage II (enlarged nodes plus lung involvement), stage III (lung involvement without significant nodal enlargement), and stage IV (lung fibrosis). Staging is descriptive and does not by itself predict the course or treatment, but it provides a useful framework for discussion.
The disease behavior is highly variable. Many people with sarcoidosis—particularly those with limited disease confined to thoracic nodes—have minimal or no symptoms and may experience spontaneous improvement over months to years. Others develop persistent or progressive disease that requires treatment. Common symptoms include cough, shortness of breath, chest discomfort, fatigue, low-grade fever, night sweats, and weight loss. Some patients present with characteristic syndromes such as Löfgren syndrome (fever, painful red bumps on the legs called erythema nodosum, joint pain, and bilateral hilar lymphadenopathy), which often has a favorable prognosis. Extrapulmonary involvement can produce skin lesions, eye inflammation (uveitis), heart rhythm disturbances or weakness of the heart muscle, neurological symptoms, or abnormal liver and kidney tests.
Chest X-ray is often the first study to suggest sarcoidosis, particularly when bilateral hilar lymphadenopathy is identified. CT of the chest provides more detailed information about the location, distribution, and characteristics of enlarged lymph nodes, as well as lung involvement, which often shows a characteristic pattern along the bronchovascular bundles and in the upper lobes. Pulmonary function testing assesses how lung function is affected. Blood tests may show elevated calcium, abnormal liver tests, or elevated angiotensin-converting enzyme (ACE) levels (though ACE is not specific or sensitive enough to diagnose sarcoidosis on its own). Tissue confirmation, often through endobronchial ultrasound-guided biopsy of mediastinal or hilar lymph nodes, is typically needed to support the diagnosis and exclude conditions that can mimic sarcoidosis, such as lymphoma, tuberculosis, fungal infection, or metastatic disease. Additional testing—including eye examination, ECG and cardiac imaging, and evaluation of other organs—is often performed to assess the full extent of disease.
Important to Know
Many patients with sarcoidosis, especially those with limited involvement of thoracic lymph nodes and minimal or no symptoms, can be observed without specific treatment. Spontaneous improvement is common, and unnecessary treatment can expose patients to side effects without clear benefit. Regular follow-up with imaging, pulmonary function testing, and symptom review is often the mainstay of care for these patients.
For symptomatic patients—or those with significant involvement of the lungs, eyes, heart, nervous system, kidneys, or other organs—treatment is generally needed. Corticosteroids (such as prednisone) are typically the first-line therapy. Other immune-modulating medications (such as methotrexate, azathioprine, mycophenolate, or biologic agents like TNF inhibitors) may be used when steroids are inadequate, poorly tolerated, or when long-term immunosuppression is needed. Treatment of associated conditions—such as elevated calcium, fatigue, or specific organ involvement—is individualized.
Care is typically coordinated by a multidisciplinary team that may include pulmonologists, primary care clinicians, rheumatologists, cardiologists, neurologists, dermatologists, ophthalmologists, and other specialists depending on which organs are affected. Patient education, vaccinations, and management of associated mental health and lifestyle issues are also important parts of care.
Because sarcoidosis can mimic other serious conditions—including lymphoma, tuberculosis, and certain infections—accurate diagnosis is essential. Imaging findings are interpreted together with the patient’s history, examination, biopsy results, and laboratory studies.
Red flag symptoms include rapidly worsening shortness of breath, severe chest pain, palpitations or fainting, severe headache or new neurological symptoms, vision changes, persistent high fever, significant unintended weight loss, severe fatigue, or worsening symptoms in known sarcoidosis. These warrant prompt medical evaluation.