Lymphoma

my dad, age 60, was diagnose with NHL last year 2008.  He underwent 6 chemo sessions.  He was doing fine post treatment, he regained weight/mobility and was in fact planning to return to work. It has been about 7 months since his last chemo. In the last two weeks, things started to go down hill.  His right leg and abdomen started swelling.

We took him to the emerg where his surgeon ordered a CT scan, it was done without trace because his kidney function was not well.  The result of the scan showed a "mass" on the right side kidney and couldn't tell what it was.  Surgeon suspected the lymphoma was back.  The next day he called and said a few Radiologist said my dad's lymph nodes have actually shrunk since a CT scan completed in Dec of 08 and the "mass" could be some sort of bleeding.

Next came the Oncologist. Looking at my  dad he suspects that the cancer is back....in fact an aggressive lymphoma resistant to treatment?  As of today he admitted my dad for some tests.....an ultra sound was done and we're awaiting a biopsy to be done.

My question is, if the lymphoma was back wouldn't the lymph nodes be swollen? Is something else possibly going on by the right side kidney?  has anyone experience something similar?  I asked the Oncologist if this could be lymphadema and that was ruled out also.

thanks in advance