My father in law had a small tumour removed from his head which turned out to be malignant. his doctor wants to do an ultra sound of his throat - why?

What is Pathology?: The tumor was likely diagnosed by a pathologist. If it appears to have arisen from the throat, than it may be arising from the pharynx or one of the salivary glands. An ultrasound may not be able to see that deep, and I would suggest that he undergo a CT scan of the neck, with contrast, as this can see the deep structures of the neck in better detail.