An eight-year-old boy had abdominal pain, fever with bloody diarrhea for 18 months. His height is 100 cm and weight is 14.5 kg. Stool culture was negative for known entero-pathogens. The sigmoidoscopy was normal. During the same period child had an episode of renal colic and passed urinary gravel. The Mantoux test was 5 x 5 mm. The most probable diagnosis is:

The boy in question is obviously malnourished (Expected weight is 20-25 kg and expected height is 125-130 cm) A normal sigmoidoscopy rules out ulcerative colitis as it extends in a continuous fashion proximally from the rectum. A negative Mantoux test goes against active tuberculosis and a negative stool culture also rules out strongyloidiasis. Interpretation of Mantoux test: If the width of the induration is: >= 10 mm: Positive (tuberculin reactors) 6-9 mm: Equivocal/doubtful reaction <=5 mm: Negative reaction Hence, the obvious choice left is option '2', i.e. Crohn's disease.