You wrote that at your first diagnosis you had no MALT in your bone marrow. However, only a bone marrow biopsy could have given your docs that information. So, either you didn't have a bone marrow biopsy initially and somebody misspoke at your diagnosis by saying it wasn't in your bone marrow, or you had a bone marrow biopsy at diagnosis.
It happens all the time that the bone marrow results will change. Once anyone is diagnosed their lymphoma doesn't stay precisely the same forever. That's why as time goes by there are scans to monitor you, comparisons with early tests, etc. as needed, to see how your MALT may be changing.
Maybe it would be helpful for you to join a group strictly for those with MALT lymphoma, since it is pretty rare. nhl-malt@yahoogroups.com is a good one. It's been very helpful to me.
Best wishes,
Carol