Here is a vignette contributed by a Respiratory colleague:

A middle-aged lady with IgA nephropathy on hemodialysis for 6 months presented with a one-month history of fever. Septic work up was negative and she did not respond to multiple courses of antibiotics. A CT thorax was subsequently performed.

Question(s): What are the differential diagnoses and what should be performed next?

[Updated 5th August 2016]

The CT cuts show an enlarged subcarinal lymph node. Rest of the lung fields were not shown but there were no other lesions/infiltrates. The most likely diagnosis remains tuberculosis but lymphoma is also a possibility.

Endobronchial ultrasound (EBUS) of the subcarinal lymph node was performed, with fine needle aspiration (FNA) performed under EBUS guidance.

The direct smear preparations of the FNA samples showed several granulomas comprising aggregates of epithelioid histiocytes and few multinucleated giant cells in a background of abundant suppurative necrotic debris. Some granulation tissue is also seen. Clusters of benign bronchial epithelial cells are also noted.

TB molecular of the EBUS smear was positive and the patient was treated as for tuberculosis.