ABSTRACT
Hematopoietic cells travel continually through the circulatory and lymph systems. Some autoimmune diseases are also associated with an increased risk of lymphoma, particularly extranodal marginal zone/mucosa-associated lymphoid tissue lymphoma in patients with Hashimoto’s thyroiditis, and lymphoepithelial sialadenitis associated with Sjogren’s syndrome. The transit of lymphocytes from circulation into secondary lymphoid organs, for example, lymph nodes (LNs) and Peyer’s patches (PPs) is the best understood example of leukocyte trafficking from blood into solid tissues. Lymphocyte homing to LNs and PPs through high endothelial venules occurs constantly and at a very high rate, which has led to our intricate knowledge of these processes gained through intravital microscopy. The intestinal lamina propria contains numerous previously activated/memory CD4+ T-cells involved in intestinal immunity and the induction and maintenance of chronic intestinal inflammation. Hepatosplenic T-cell lymphoma is distinguished by hepatosplenomegaly, minimal or no lymphadenopathy, frequent bone marrow involvement, and a distinctive pattern of intrasinusoidal infiltration of tumor cells.
