Shouldnt your white blood count be up if you have pneumonia or any other infection?

I took my mother to the emergency room last night and for stomach pain so they did an ct scan and said that they did not find nothing in the abdominal area and that she had a mass in her lung and said that she either has pneumonia or she has lung cancer but her blood work was fine .Should i take her to get a second oppinon

If your mum had a CT scan, the Radiologist would be able to define if the mass was cancer or not. Otherwise, what sort of a Dr is he?
Your mum's blood tests would also confirm either cancer or Pneumonia, did you go to a hospital or a circus?

in some cases the white count is not high during the infection.

well if she had some kinda stomach infection her wbc count would be up as well.......she needs to go to the doc and make sure she doesn.t have a cancer that is pressing against other parts of her body and causing pain.......she needs to go to another doc to determine what is wrong.......people can be atypical in their bloodwork

If you are not happy you should go for a second opinion. There is a big difference between pneumonia and lung cancer?!! Did they suggest any further tests or anything?

Viral pneumonia will not raise the wbc count. The radiologist cannot determine whether your Mom's tumor is cancerous or not. Only a biopsy can determine that. The tumor can only look suspicious.
A follow-up appointment with her primary physician is crucial, to determine what is going on with her.