Miliary sarcoidosis

Miliary sarcoidosis is a rare thoracic manifesation of sarcoidosis where there are numerous miliary-like nodules scattered throughout the lungs. It is thought to represent less than 1% of cases. 

Epidemiology

From the limited case reports available, there is some suggestion that this form may occur in a slightly older age group (e.g. fifth decade ²)

Radiographic features

Plain radiograph

Tiny nodules in the range 1 to 5 mm in size distributed bilaterally throughout the lungs. There may be some upper zone predominance and hilar lymphadenopathy to help distinguish it from miliary tuberculosis and miliary metastases however they can be identical.   

CT

In this form, the tiny nodules may be distributed in a random miliary-like manner without the typical galaxy configuration.  Concurrent supportive features such as lymphadenopathy may be present in some cases.

Differential diagnosis

On CT imaging, consider other causes of miliary nodular opacities, such as

• miliary tuberculosis

• pneumoconioses

• miliary metastatic lesions

For a broader differential for miliary pattern in the lungs - refer to miliary opacities