Symptomatic Massive Splenomegaly in Persistent Polyclonal B-cell Lymphocytosis Requiring Splenectomy

INTRODUCTION: 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. CASE PRESENTATION: 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. DISCUSSION: 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. CONCLUSION: 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.