17th January 2024

Differential diagnoses

Lymphoma

For patients presenting with bilateral hilar lymphadenopathy, lymphoma is an important differential. They can also present with “B-symptoms” of weight loss, night sweats and persistent fatigue, all of which can also occur with sarcoidosis. Differentiating features would include painless lymphadenopathy elsewhere and splenomegaly. Full blood count and blood film are minimally invasive investigations which can help with the diagnosis, but if there is a significant diagnostic uncertainty, a lymph node biopsy or bone marrow aspirate should be undertaken.

Tuberculosis

Pulmonary tuberculosis (TB) presents with cough, haemoptysis and shortness of breath in addition to systemic symptoms such as weight loss, fevers and night sweats. Appearance of hilar lymphadenopathy can be similar to sarcoidosis on chest x-ray. TB is characterised by caseating granulomas, whereas sarcoidosis is associated with non-caseating granulomas. Travel and exposure history are important in delineating risk of an infective cause of symptoms, particularly where there are red flag symptoms such as haemoptysis. It is important to rule out TB prior to giving immunosuppressive therapy.

Interstitial lung disease

In patients with fibrosis on imaging, it is important to consider other forms of interstitial lung disease. Diseases of occupational exposure, such as berylliosis and silicosis, can have a similar CT appearance, so a thorough occupational history is key.