Another young man from South Asia, who had been working in the construction industry in Singapore for a few years, was incidentally found to have a painless mass over the left upper quadrant of his abdomen during a routine medical examination. He mentioned that it had appeared over the past week, gradually increasing in size. He was otherwise well, with no fever, loss of weight, or other constitutional symptoms. A CT scan was organised.

Question: What has caused the lump and what is the likely underlying diagnosis?

[Updated 17 March 2016]

The CT and photo together show a multiloculated splenic collection that has tracked outwards to form a subcutaneous collection. Note that there is also a peri-hepatic collection that is not easy to see on the single cut of the CT shown. There are two main differentials here given disease presentation and epidemiology – disseminated tuberculosis with cold abscesses, and melioidosis. Given that the young man was relatively asymptomatic, and that there was a peri-hepatic collection as well, the former is far more likely. Aspiration of the subcutaneous collection showed creamy thick whitish pus which was positive for tuberculosis using PCR testing.