Systemic follicular lymphoma with massive intestinal involvement with leukemic manifestation.

A 30-year-old man was referred to our hospital with leukocytosis and fecal occult blood. His white blood cell count was 30.2 × 10(9)/L with 79% small- to medium-sized lymphocytes. Surface antigen analysis revealed that these lymphocytes were positive for CD19, CD20, CD10, and CD23, but negative for CD5. The lymphocytes infiltrated the bone marrow. On endoscopic examination of the duodenum and jejunum, many small polypoid lesions were observed. A histologic picture of a biopsied lesion showed diffuse infiltration of small- to medium-sized lymphocytes in the submucosal region. On immunohistochemistry, these lymphocytes were positive for CD20, BCL2, and CD10 (weakly). Polymerase chain reaction analysis of cells from peripheral blood, bone marrow, and intestinal lesion showed a fusion product of BCL2 and immunoglobulin heavy chain (IGH) genes. The fused BCL2/IGH gene was also demonstrated by fluorescence in situ hybridization in the same cell sources. Computed tomography scanning showed marked wall thickening throughout the small intestine and enlarged mesenteric lymph nodes. A diagnosis of follicular lymphoma with massive intestinal involvement in a leukemic state was made. After 6 courses of rituximab-combined CHOP chemotherapy, complete remission was obtained.