Most animals, including humans, might have a little lump here and there that are not significant and do not represent a health risk.
Cockatiels can have abscesses. An abscess is a collection of pus caused by a bacterial or fungus infection and is potentially dangerous. Veterinarian attention is required or the infection can spread to the rest of the body.
Your vet will probably drain the abscess and put your cockatiel on special antibiotics. Your vet will also give instructions on how to care for your cockatiel's abscess while at home.
If the bird is a female, an abdominal bulge may in fact be an egg.
A lump can also be a tumor, but only an Avian Vet will be able to determine that. There are several different types of tumors, fatty tumors, kidneys, thyroid, adrenal tumors these are just a few. Some tumors can go into remission just like cancer does for humans.
Your vet will run tests to make sure if it is a tumor or do an x-ray as many will show up this way. Other masses are actually large deposits of fat that are beneath the skin, similar to a "spare tire" in people.
As always the information offered here is to provide guidance and is not intended to be a substitute for the good advice provided by your own avian vet. When in doubt always consult your own veterinarian.
Pet birds can develop many different types of cancer, and cancer can occur at any age, although older birds are most at risk. The most common type of cancer seen in birds is squamous cell carcinoma, or malignant skin cancer. The most common areas affected include the skin on the bird's head, on or around her beak, around the uropygial gland, and on or around the eyelids. Although this type of cancer can affect any breed, cockatiels, lovebirds, and parakeets are the most prone to it.
A feather cyst is equivalent to an ingrown hair on a human except it is much bigger. A feather cyst occurs when a growing feather is unable to protrude through its natural opening in the skin, and curls up within the follicle into what is sometimes a gnarled up feather mass. Feather cysts appear visibly as oval or elongated swellings involving one or sometimes multiple feather follicles.
If your cockatiel has a feather cyst, it would be best for your avian vet to take care of it.