Radiological appearance of sarcoidosis

Bilateral hilar lymphadenopathy (BHL), the classic radiographic feature of sarcoidosis is seen in around three quarters of the patients (1).

Concomitant involvement of the right paratracheal lymph nodes can be seen in some patients (1).

Pulmonary parenchymal infiltrates (with or without BHL) is seen in 20% to 50% of sarcoidosis patients

• may present as patchy or diffuse infiltrates
• mainly involves the upper and mid lung zones
• reticulonodular infiltrates, macroscopic nodules, consolidation or mass like lesions may be seen

Once fibrosis of the lungs occurs chest radiography may reveal loss of volume, hilar retraction, and coarse linear bands (1).

The appearance of the chest radiograph permits prognostic classification of disease.

Radiological staging has four categories (1):

• stage 1 - bilateral hilar lymphadenopathy (BHL) only (likelihood of spontaneous remission 55-90%)
• stage 2 - BHL plus pulmonary infiltrate (likelihood of spontaneous remission 50-70%)
• stage 3 - peripheral pulmonary infiltrates alone (likelihood of spontaneous remission 10-20%)
• stage 4 - pulmonary fibrosis (likelihood of spontaneous remission 0%) (progressive pulmonary infiltration, pleural involvement, bulla formation (honeycombing)(2)

Reference:

• 1. Lynch JP 3rd et al. Pulmonary sarcoidosis.Semin Respir Crit Care Med. 2007;28(1):53-74
• 2. Dempsey OJ et al. Sarcoidosis. BMJ. 2009 Aug 28;339:b3206