Plasmacytic differentiation in MALT lymphomas following treatment with rituximab

Abstract

Mucosa-associated lymphoid tissue (MALT) lymphomas are B cell neoplasms which commonly affect the gastrointestinal (GI) tract. Gastrointestinal MALT lymphomas rarely show plasmacytic differentiation (PCD), and limited data on the potential influence of the anti-CD20 antibody rituximab (R) on PCD exist in the current literature. We have retrospectively analyzed patients with GI MALT lymphomas treated with R-containing regimens because restaging is routinely performed by repeated biopsies with pathohistological response assessment. Twenty-one patients with GI MALT lymphoma were identified to have undergone R-containing therapy. In 19 patients, the lymphoma originated in the stomach, while the colon was the primarily affected organ in two cases. Four patients received R monotherapy and 17 combinations of R with various chemotherapeutic agents. Only two patients with gastric MALT lymphoma had PCD before initiation of therapy. In 7 of 19 patients (37%) without PCD at diagnosis, restaging revealed PCD after or while on treatment with R-containing regimens. Out of these seven patients, only one patient had a complete response as opposed to 10/12 without PCD. These data suggest that R or R-containing treatment regimens may not optimally eradicate the plasma cell component and thus lead to PCD in patients with GI MALT lymphoma. In view of this, rebiopsy and histological re-assessment appear mandatory in patients failing/relapsing after R-containing regimens.

Rituximab plus subcutaneous cladribine in patients with extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue: a phase II study by the Arbeitsgemeinschaft Medikamentose Tumortherapie

“…11 However, development of refractoriness to treatment due to plasmacytic differentiation was not a problem in our study and also has not been found in patients being given rituximab along with fludarabine. The effects of this latter combination were reported by Salar et al, who studied a cohort of 22 patients with MALT lymphoma.…”

“…While the role of the chimeric anti-CD20 antibody rituximab in combination with chemotherapies is undisputed in almost all types of B-cell lymphomas, its use in MALT lymphoma is being tested in an ongoing randomized trial and it is currently not approved for this indication in Europe. Although it has been shown to have good palliative potential in patients with MALT lymphoma, 7 various caveats such as suboptimal penetration of the antibody into the gastric mucosa 7 and induction of plasmacytic differentiation 11 have been raised. The latter might lead to resistance of the disease to rituximab-containing therapies, as plasma cells are devoid of CD20 expression.…”

Extranodal Marginal Zone Lymphoma of the Lung: Evolution from an Underlying Reactive Lymphoproliferative Disorder

“…MALT lymphomas are usually composed of a heterogenous mixture of the cells; however, between one-fourth and one-third of MALT lymphomas display prominent plasmacytic differentiation [7,8] as was seen in this case. This variant is not associated with a difference in clinical presentation or prognosis [7], although MALT lymphomas arising outside the gastrointestinal tract are more likely to demonstrate this morphology [9]. Of note, patients treated with rituximab therapy may eventually show a shift in differentiation toward the plasmacytic variant due to selective proliferation of the CD20-negative cells [9,10].…”

“…Dutcher bodies (intranuclear inclusions), Russell bodies (cytoplasmic vesicles containing immunoglobulin), and Mott cells (plasma cells that contain numerous Russell bodies) are also common findings in MALT lymphoma [5,6]. MALT lymphomas are usually composed of a heterogenous mixture of the cells; however, between one-fourth and one-third of MALT lymphomas display prominent plasmacytic differentiation [7,8] as was seen in this case. This variant is not associated with a difference in clinical presentation or prognosis [7], although MALT lymphomas arising outside the gastrointestinal tract are more likely to demonstrate this morphology [9].…”

Primary Small Intestinal Mucosa-associated Lymphoid Tissue Lymphoma Diagnosed by Balloon-assisted Enteroscopy

“…The treatment for gastric MALT lymphomas generally includes H. pylori eradication therapy (7), radiation therapy (8), chemotherapy (9), and surgery. In contrast, there is no consensus regarding treatment of small intestinal MALT lymphomas.…”