Cysts: Cysts are fluid-filled sacs that can form anywhere on the body, including the chest. They are usually benign and do not cause any problems, but they can sometimes become infected or grow large enough to interfere with breathing or other bodily functions.
Tumors: Tumors are abnormal growths of tissue that can be either benign or malignant. Malignant tumors, or cancer, can spread to other parts of the body and be life-threatening.
Abscesses: Abscesses are pockets of pus that form when bacteria or other foreign material gets trapped in the body. They can be painful and can cause serious health problems if not treated properly.
Hernias: Hernias occur when an organ or other tissue protrudes through a weakness in the muscle or connective tissue. They can be painful and can lead to serious health problems if not treated properly.
Impacted crop: A budgie's crop can become impacted (blocked) causing a firm feeling lump to appear just underneath the bill at the front of the chest
It is important to take your budgie to the vet if you notice a lump on his chest. The vet will be able to determine the cause of the lump and recommend the best course of treatment.