Teaching Case

A 25-year-old man was referred from another hospital with a 2-month history of fever, erythema nodosum and lower extremities joints pain. Chest radiograph (Fig. 1) was performed, followed by thoracic CT scan (Fig. 2) and EBUS (endobronchial ultrasound) biopsy. Histopathology was positive for non-necrotic epithelial granulomas.

Chest radiographs (Fig. 1) revealed bilateral hilar lymphadenopathy and paratracheal lymph node enlargement. There were no pulmonary opacities.
CT scans (Fig. 2) showed bilateral hilar, paratracheal, subcarinal and prevascular lymph node enlargement. There were no pulmonary abnormalities.

Sarcoidosis is a systemic disease of unknown aetiology that is characterized by formation of noncaseating granulomas. Even though they may be found in any organ, most commonly affected structures are hilar and mediastinal lymph nodes, lungs, skin and eyes. Sarcoidosis incidence varies greatly around the world, from about 1.01 to 35.5 in 100 000. The highest prevalence is reported in African–American, Danish and Swedish individuals, and the lowest in the Japanese population. [1]

Sarcoidosis is often (in 30-60%) asymptomatic, the only finding being abnormal chest imaging studies. Clinical symptoms if present include persistent cough, fatigue, fever, erythema nodosum, joints pain, uveitis and peripheral lymph node enlargement. [2]

Pathologic chest radiograph findings are reported in 60% to 70% of patients with sarcoidosis. [3] The pattern of these chest radiographic abnormalities is a basis of classic sarcoidosis staging system (Fig. 3) [4]
Stage 1 is described as isolated intrathoracic lymphadenopathy. The most typical chest radiograph lympadenopathy pattern, occurring in 85-95% of diagnosed patients, is bilateral, symmetric, well-defined hilar lymph node enlargement. Right paratracheal lymph nodes are enlarged in 75% of cases. Together they form a sign named Garland's triad or a 1-2-3 sign. Lymphadenopathy in other localizations is less frequent, it is found in 50-75% in the aortopulmonary window, 20% in the subcarinal region, 10-15% in the anterior mediastinum, <5% in the posterior mediastinum, <5% intramammary. (Fig. 4) [3] Lymph node enlargement usually resolves in 2 years’ time, however it may persist for many years. Recurrence following resolution is uncommon. Lymph node calcifications are reported in chest X-rays of up to 20% of patients with sarcoidosis lasting for 10 year or more. [5]
CT (computed tomography) due to its superior sensitivity displays a different pattern of lymphandenopathy in patients who have sarcoidosis. Right lower paratracheal lymph nodes are enlarged in 100%; subaortic and paraaortic lymph nodes (lymph nodes of aortopulmonary window) in 95%; hilar in 90%, prevascular in 65%; in posterior mediastinum in 15%. Calcifications are observed in CT in 25-50% of patients, and its prevalence increases with disease duration. In contrast to densely calcified lymph nodes characteristic for tuberculosis, sarcoid lymph nodes often display a hazy or eggshell calcification pattern. [3]
Even though lymphandenopathy in sarcoidosis is often prominent, it rarely causes any symptoms. [6]

Take home message
Sarcoidosis is the most common cause of bilateral asymptomatic hilar lymphadenopathy and should always be included in the differential diagnosis of such a finding.