If a lymph node is round with a well defined border and no fatty center is it always malignant?

More info needed: The only way to tell if a lymph node is malignant is to biopsy it (take it out and look at it under the microscope).

Imaging: Usually if the doctor has a suspicion that the lymph node may be abnormal (bigger than usual, hard, several of them) they will obtain a ct of the area and then consider a biopsy. A biopsy where a piece of the lymph node or full removal of the lymph node gives the most information. Sometimes a very fine needle is put into the lymph node but that may not reveal the overall problem.

No: What you describe sounds like an ultrasound report of a lymph node. The only way to know for sure that a lymph node is malignant is to biopsy it (take a small sample of it.).