Miliary opacities (lungs)
The term miliary opacities refers to innumerable, small 1-4 mm pulmonary nodules scattered throughout the lungs. It is useful to divide these patients into those who are febrile and those who are not.
Additionally, some miliary opacities are very dense, narrowing the differential - see multiple small hyperdense pulmonary nodules.
The causes can be broadly subgrouped dependent on whether or not the patient is febrile.
- miliary metastases
- sarcoidosis: miliary sarcoidosis
- pulmonary hemosiderosis
- hypersensitivity pneumonitis
- Langerhans cell histiocytosis (LCH)
- multifocal micronodular pneumocyte hyperplasia (MMPH)
- diffuse pulmonary meningotheliomatosis
- pulmonary alveolar proteinosis
- small acinar opacities can mimic a miliary pattern
- hypersensitivity pneumonitis (mild fever if any)
History and etymology
The term miliary is derived from the millet seed, a term used to describe a group of small-seeded species of cereal crops or grains, widely grown around the world for food and fodder .