A ten-year old girl presents with swelling of one knee joint. All of the following conditions can be considered in the differential diagnosis except -
Tuberculosis
Juvenile rheumatoid ahritis
Haemophilia
Villonodular synovitis
Ans. is 'c' i.e., Haemophilia Although all conditions mentioned in the options may produce swelling of one knee joint, the clue lies in the fact that haemophilia is an X Linked recessive disease and is not manifested in girls who act only as carriers.