A case of AL amyloidosis associated with follicular lymphoma with plasmacytic differentiation.

A 58-year-old woman underwent emergency surgical resection of the small intestine for intussusception as diagnosed at our hospital. Histopathological diagnosis of the resected specimen of the ileum was amyloid light chain (AL) amyloidosis. The colonoscopy after the surgical resection and following histopathological analysis of the biopsied specimens of the colon revealed follicular lymphoma (FL) grade 1 with plasmacytic differentiation. Histological findings of these ileal and colonic lesions were characteristic. In the ileum, CD10-positive lymphoid follicles and CD38-positive interfollicular plasma cell infiltration into villi were detected. The amyloid deposition was localized to the ileum and was adjacent to lymphoid follicles and interfollicular plasma cells. Furthermore, fluorescence in situ hybridization (FISH) for paraffin-embedded tissue sections (tissue-FISH) revealed that both the B cells in follicular lesions and the interfollicular plasma cells showed IGH/BCL2 fusion signals, which means the interfollicular plasma cells were originated from the differentiated neoplastic follicular B cells. The patient was treated with six courses of lymphoma chemotherapy and attained complete remission without any symptoms associated with amyloidosis. Further case analyses are needed to clarify the clinicopathological findings and to establish therapeutic strategy of AL amyloidosis associated with FL and FL with plasmacytic differentiation.