Primary splenic diffuse large B-cell lymphoma manifesting in red pulp

We evaluated six cases of diffuse large B-cell lymphoma (DLBCL) involving the red pulp of the spleen. All had B symptoms and an aggressive clinical course. The lymphoma cells proliferated diffusely and non-cohesively in the cords of the red pulp. The lymphoma involved the bone marrow in four of the five patients and the liver in all four of the patients examined. However, lymph node (LN) involvement was rare at presentation, and systemic LN involvement was not observed even in the terminal phase. The lymphoma cells infiltrated the intrasinusoidal/intravascular and interstitial spaces of the involved tissues and were detected in the peripheral blood in two of the six patients. CD5-expressing lymphoma cells were detected in four of the five patients examined. Because these cases had some unique clinical features and occurred in distinct splenic sites, we proposed that primary splenic DLBCL manifesting in red pulp is a distinct clinicopathological entity.