Systemic polyclonal B-immunoblastic proliferation with marked peripheral blood and bone marrow plasmacytosis.

The clinical and pathologic features of a case of acute systemic polyclonal B-immunoblastic proliferation characterized by pronounced peripheral blood and bone marrow plasmacytosis and infiltration of the hepatic portal areas by immunoblasts, plasma cells, and lymphocytes are reported. Clinical and laboratory findings during the acute phase and long-term follow-up support the diagnosis of a benign process, possibly related to Pseudomonas aeruginosa septicemia. The patient experienced a dramatic clinical recovery on administration of high-dose intravenous corticosteroids. Pathologists should be aware of this entity so as not to confuse it with non-Hodgkin's lymphoma or a form of plasma cell dyscrasia.