Hello and welcome to HCM,
A mass (?site unknown) with history of
weight loss and
fever are very much suggestive of a cancer.
You need to consult your treating doctor as soon as possible.
The mass needs to be investigated.
Depending on its site relevant investigation will be required- aspiration cytology or
biopsy.
Aspiration cytology or biopsy will determine the origin and nature of the lesion.
If the mass turns out to be malignant, treatment in the form of surgery,
chemotherapy and/ or radiotherapy will have to be planned.
Treatment will depend on the site and type of lesion.
It is difficult to say why the mass did not appear on imaging earlier.
Probably it was too small to be detected.
Your treating doctor will be in a better position to answer that.
Thanks and take care
Dr Shailja P Wahal