Can you give us any background on this fish? How long has the owner had him? Was he QT'd and were the other fish in the tank with him QT'd as well? Any behavioral symptoms like flashing, scratching, heavy breathing, lethargy, lack of appetite? Anything else you can think of that might be relevant?
Can he do a freshwater dip on it to see if that dislodges those nodules? They really do look like lymph, but he should be otherwise normal if it were lymph. The dip will act as a diagnostic tool for us.