We report the case of a patient with
lymphoma of the salivary gland, at first diagnosed as
lymphoma of mucosa-associated lymphoid tissue (
MALT lymphoma) but later found to infiltrate the bone marrow. At diagnosis, the patient had a polyclonal increase of
gamma-globulins. Five years after initial diagnosis, the patient presented with
monoclonal gammopathy and infiltration of the bone marrow with neoplastic cells. Initially, the patient had received
chemotherapy with different protocols (including
etoposide,
cyclophosphamide, fludarabin,
methotrexate, and
vincristine), none of which induced a lasting response.
Therapy with
rituximab (chimeric anti-CD20
monoclonal antibody) finally led to partial remission. Eighteen months after
rituximab, progressive
lymphoma in the abdomen and a
monoclonal gammopathy developed. The bone marrow showed infiltration by lymphoplasmacytoid cells (monoclonal expression of the light-chain type lambda, positive for CD20, heterogeneous expression of CD45). The patient achieved another short clinical response with 4 cycles of the
CHOP-protocol, but soon the
lymphoma progressed again. Five years and 8 months after the initial diagnosis, the patient died from
septicemia and progressive
lymphoma. By polymerase chain reaction (PCR) for the IgH gene it was shown that
lymphoma cells were initially oligoclonal in the salivary gland and, later, biclonal in the bone marrow. Sequencing of two bands of apparently same length showed that these manifestations of
lymphoma were not identical. Taken together, our data show that the initial low-grade oligoclonal
MALT lymphoma was no longer present and a more aggressive biclonal
lymphoma with plasmacytoid differentiation had developed. The new
lymphoma was clonally distinct and produced high amounts of monoclonal
IgG lambda by immunoelectrophoresis. The relationship of the second
lymphoma to the initial
MALT lymphoma is discussed.