Leukemic Non-Nodal Mantle Cell Lymphoma Presenting with Traumatic Splenic Rupture

Background: Leukemic non-nodal variant mantle cell lymphoma (nnMCL) is an uncommon subtype of mantle cell lymphoma that lacks lymphadenopathy and generally follows an indolent clinical course. Adverse genetic alterations such as TP53 inactivation and del(13q) may have prognostic significance. Clinical findings such as splenomegaly may serve as a clue to the diagnosis and should prompt further evaluation. Case Presentation: We describe a 91-year-old woman who presented with a one-month history of anemia (hemoglobin 12.3 g/dL), mild thrombocytopenia (platelets 136 × 10⁹/L), isolated splenomegaly and no palpable lymphadenopathy. Despite a normal total white blood cell count, intermittent relative lymphocytosis with atypical lymphocytes (4%) and smudge cells was detected on the complete blood count. Peripheral blood flow cytometry demonstrated a monoclonal kappa-restricted B-cell population negative for CD5 and CD10, comprising approximately 20% of lymphocytes. Conventional karyotyping and fluorescent in situ hybridization (FISH) analysis identified del(13q), del(17p)/TP53, and IGH-CCND1 rearrangement in 8-19.5% of peripheral blood leukocytes. A month after the initial assessment, the patient presented following a fall. CT imaging of the abdomen revealed marked splenomegaly, a large subcapsular/perisplenic hematoma, and moderate-to-large hemoperitoneum. Emergent laparotomy showed an enlarged spleen (1490 g, 23 × 16 × 7.5 cm) with laceration. Histologic evaluation showed atypical lymphoid cells positive for CD20 and cyclin D1, with strong p53 expression, negative for CD5 and SOX11, and a low Ki-67 index. Similar involvement was identified in the small bowel and appendix. Targeted sequencing of splenic tissue, performed as part of a retrospective molecular characterization, identified a pathogenic TP53 variant (p.His179Gln). Conclusions: This case provides a rare opportunity to evaluate splenic and small intestinal involvement by nnMCL at both the gross and histologic levels. It highlights the importance of integrating clinical findings with flow cytometry, imaging, cytogenetic, and molecular data in establishing the diagnosis. Even when peripheral blood findings suggest a low disease burden, imaging may better define the extent of disease and support appropriate clinical assessment, particularly in elderly patients at risk for complications related to splenomegaly.