In a Clinical Crossroads article published in November 2001, Michael
Iseman, MD, discussed a 52-year-old man, Mr Z, who had recently returned from
Bangladesh, an area endemic for tuberculosis (TB), with a dry, hacking cough.1 His purified protein derivative (PPD) test yielded
a positive result with 22 × 28 mm of induration; a chest radiograph
was normal. His primary care physician, Dr L, was not convinced that the positive
PPD represented a recent conversion to TB, and, after considering with the
patient the potential risks of treatment, elected not to treat him at that
time.