Diffuse Large B-Cell Lymphoma Presenting as Clinically Isolated Massive Splenic Disease: A Case Report

Diffuse large B-cell lymphoma (DLBCL) presenting as clinically isolated massive splenic disease is uncommon and may pose substantial diagnostic and therapeutic challenges. We report a 47-year-old woman who presented with six months of progressive left upper quadrant pain, abdominal fullness, anorexia, early satiety, intermittent dyspnea, fatigue, fever, night sweats, and a 7 kg unintentional weight loss. Examination revealed massive splenomegaly without peripheral lymphadenopathy. Laboratory investigations showed leukocytosis with neutrophilic predominance and elevated lactate dehydrogenase. Contrast-enhanced computed tomography (CT) demonstrated a markedly enlarged spleen measuring approximately 37 × 25 × 15 cm without significant thoracic, abdominal, or pelvic lymphadenopathy. Because of severe mass effect symptoms, extreme splenic enlargement, and the need for definitive tissue diagnosis, elective open splenectomy was performed. The spleen measured 40 × 27 × 12 cm and weighed 7.5 kg. Histopathology demonstrated diffuse effacement of splenic architecture by large atypical lymphoid cells. Because immunohistochemical facilities were unavailable at the treating institution, representative paraffin-embedded tissue blocks were evaluated at an external laboratory by a hematopathologist. Immunohistochemistry demonstrated CD20, CD79a, and PAX5 positivity; CD3 and CD5 negativity; CD10 and BCL6 positivity with MUM1 negativity; a Ki-67 proliferation index of approximately 80%; and MYC and BCL2 expression below commonly used double-expressor thresholds. These findings confirmed DLBCL of germinal center B-cell phenotype involving the spleen. Postoperative contrast-enhanced CT of the chest, abdomen, and pelvis showed no significant nodal or additional visceral disease, supporting a clinically localized splenic presentation. Pretreatment and post-treatment 18F-FDG PET-CT and bone marrow assessment were not performed because of resource and logistical limitations; therefore, occult systemic or marrow involvement could not be definitively excluded, and PET-based metabolic response could not be assessed. The patient received six cycles of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) every 21 days, beginning 28 days after surgery. At 18 months after completion of chemotherapy, she remained clinically well with no evidence of recurrent disease on surveillance clinical examination and CT. This case emphasizes the importance of adequate tissue diagnosis, external expert immunophenotypic confirmation when required, careful systemic staging, and individualized consideration of open splenectomy in patients with symptomatic extreme splenomegaly.