Your sister is having fever for the last 3 months. Do you have objective documentation of the fever 38/39/40 degree etc. is it associated with sweating and weight loss
. WBC count
is zero ? What is your sister's age. Any other important medical history with your sister and within the family. Occupation. Any history of miscarriage
or still birth if she is married and if she is in the age of getting pregnant.Pleural effusion
is significant. Better to get the effusion fluid taken out possibly a small sample for test. This will give you an idea. If necessary she might need biopsy of the pleura (lining of the lung) done under local anesthesia
. Depending upon where you live procedure for pleural biopsy could also vary. The information you have provided in not sufficient to give you a close up to the possibilities and the likely hood is really huge. So kindly provide more information to help us narrow down our impression.