A “miliary pattern” on chest x-ray (CXR) is a distinctive finding characterized by numerous small (1-4 mm) nodules, typically uniform in size and distributed throughout both lung fields, resembling millet seeds – hence the term “miliary.”
Miliary patterns are most commonly associated with the hematogenous spread of diseases, including infection (disseminated fungi, viruses like varicella, tuberculosis with granulomas throughout the lung), neoplasm (metastatic cancers like thyroid, melanoma, renal, breast, or GI), granulomatous diseases (sarcoidosis, silicosis), and other rare causes (pneumoconioses, hemosiderosis, and pulmonary amyloidosis).
Workup is centered around identifying the etiology through history and physical (attention to recent travel, occupational exposures, immunosuppression, and evidence of infection/malignancy), lab testing, additional imaging (e.g., high-resolution chest CT), microbiology, and biopsy. It follows that therapies range from conservative management and antibiosis to steroids and chemotherapy/radiation.
