Miliary nodules in the exam
Getting a film with miliary nodules in the exam is one of the many exam set-pieces that can be prepared for.
The film goes up and after a couple of seconds pause, you need to start talking:
There are multiple tiny soft-tissue density nodules present throughout both lungs with an upper- and middle-zone predominance. The pattern of disease suggests an inhalational cause for the underlying pathology*.
I cannot see any calcified nodules and there are no large nodules or mediastinal lymphadenopathy. The pleural spaces are clear, as are the bones.
The differential diagnosis for miliary opacities is broad and includes TB and metastases. Review of previous examinations would be helpful to determine the chronicity of the underlying disease process and highlight other co-existing pathology.
Features of infection would make pulmonary tuberculous more likely and I would highlight the result to the referring clinician to expedite respiratory referral, further investigation and treatment.
Constitutional symptoms would also be compatible with TB, but also with pulmonary metastases which would also be high on the list of differentials - this is especially true if there is a history of malignancy**. Inhalational lung disease and pneumoconioses would be considered if there were appropriate clinical history.
* the effect of gravity on blood ensures more blood at the bases and more gas in the upper zones and apices. This ventilation-perfusion mismatch is responsible for the predominance of upper zone changes in inhalational disorders and middle- and lower-zone predominance for blood-borne disease, e.g. haematogenous metastases.
** the pulmonary metastases that most commonly present as miliary opacities are:
- thyroid cancer
- ovarian cancer
- renal cancer
- breast cancer
- pancreatic neoplasms
- osteosarcoma (calcified metastases)
- trophoblastic disease