The main differential diagnoses for miliary nodules can be remembered using the mnemonic TEMPeSt: Tuberculosis, Eosinophilic granuloma, Metastases, Pneumoconiosis, Sarcoidosis.
Rather than reciting a list of differentials in an exam, a better approach is to show the examiner how you would narrow the differential. An example would be to say: 'The appearances are consistent with miliary nodules. No endotracheal tube or monitoring leads are seen, but if the patient was unwell or had a known history of TB, miliary TB is likely. I don't see any clips in the region of the thyroid or breast, but if there is a known history of cancer, miliary metastases are more likely.
If the patient has an occupational history, pneumoconiosis should be considered even though the nodules are not particularly dense. If the patient is a male smoker, I would consider Langerhans cell histiocytosis. If on review of the previous CXR, the findings are longstanding, sarcoidosis would be in the differential.'