UCSF

Persistent polyclonal B-cell lymphocytosis (PPBL) is a rare lymphoproliferative hematological disease characterized by binucleated lymphocytes, CD 19+ CD 5-lymphocytosis, and elevated levels of serum immunoglobulin M (IgM). It can rarely be associated with splenomegaly, though the disease usually remains indolent. We present a case of PPBL in a young man with massive splenomegaly that mimicked isolated splenic lymphoma requiring splenectomy for persistent pain, symptoms, and diagnosis. Determining the etiology of splenomegaly in these patients is often confounding due to a lack of a tissue diagnosis and the limited morphological and immuno-histochemical features of PPBL, therefore, the presentation remains highly concerning for lymphoma. The presentation, surgical treatment, tissue and peripheral blood molecular analysis, and flow cytometry integral to managing these patients and to prevent an assumptive and misleading diagnosis are reviewed.