Recent progress in follicular lymphoma in Japan and characteristics of the duodenal type

The incidence of lymphoma has rapidly increased over the last 40 years in Japan, following a trend that is very similar to that of breast cancer. In particular, the relative frequency of follicular lymphoma (FL) has reached that in Western countries. Given its indolence, a “watch‐and‐wait” approach is often applied to FL patients. We have shown that FL is often detected in the second portion of the duodenum and has a distinct follicular dendritic cell distribution and heavy chain variable usage similar to mucosa‐associated lymphoid tissue (MALT) lymphoma. Al though the t(14;18)(q32;q21) frequency is the same as in the nodal subtype of FL, there are also ongoing mutations, immunopositivity for cluster of differentiation 10 and B‐cell lymphoma (BCL)6, and overexpression of BCL2. Gene expression profiling has shown that it is more similar to gastric MALT lymphoma than to nodal FL. Duodenal‐type FL lacks the activation‐induced cytidine deaminase (AID) expression observed in nodal ones, although this may be compensated for by BTB domain and CNC homolog 2. Based on these findings, duodenal‐type FL has been included in the Revised 4th edition of the World Health Organization classification published in late 2017.
Source: Pathology International - Category: Pathology Authors: Tags: Review Article Source Type: research