[1312] Primary Follicular Lymphoma of the Small Intestine: A Morphologic, Immunohistochemical and Molecular Study of 7 Cases.

Carlos Martin, Rosa Kitagawa, Hernan Garcia Rivello, Dana Kohan, Esteban Mocetti, Marina Narbaitz. Hematopathology Consultation, La Plata, Argentina; Hospital Italiano, Buenos Aires, Argentina; National Academy of Medicine & Fundaleu, Buenos Aires, Argentina

Background: Primary intestinal Follicular Lymphoma (FL) is one of the variants of FL included in the 2008 WHO lymphoma classification, being the duodenum the most frequent location. Recently, several reports showed similarities to the nodal counterpart in terms of morphology, immunophenotype and molecular findings, stressing the fact that endoscopic biopsies may present some diagnostic difficulties derived from the small size of the sample.
Design: Five men and two women aged 35-73 years (mean 58,5) consulted for abdominal pain or discomfort. Endoscopic findings consisted in multiple small nodular or polypoid lesions. Biopsies were obtained in all patients. H&E stained sections were complemented with immunohistochemical stains for CD3, CD20, CD10, Bcl2, Bcl6, Ki67, Cyclin D1 and CD5. Additional molecular studies for detection of t(14;18) were performed by PCR in paraffin embedded samples.
Results: Six cases showed duodenal involvement by FL, and the remaining case was jejunal. In all cases a mucosal nodular lymphoid proliferation was seen with a variable diffuse component. Small lymphocytes and centrocytes predominated, with isolated mitotic figures. Five cases were grade 1, and two were grade 2. CD20 was positive in all cases, with co-expression of CD10, Bcl2 and Bcl6. CD5 and Cyclin D1 yielded negative results. Ki67 index was < 20%. In all cases a t(14;18) was detected by PCR (Mbr region). Staging procedures demonstrated six cases of stage IE (85,7%) and one case of stage IIE (14,3%).

Conclusions: Primary FL arising in the small intestine is a low grade indolent disease, with prevalent duodenal location, typical immunophenotype and presence of t(14;18), with some cases progressing to high grade lymphoma. This particular type of FL should be distinguished from MALT and Mantle Cell lymphomas by appropriate morphologic, immunohistochemical and molecular assessment.
Category: Hematopathology

Wednesday, March 2, 2011 1:00 PM

Poster Session VI # 198, Wednesday Afternoon


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