Durable Disease Control in Disseminated Primary Splenic Leiomyosarcoma Treated With Sequential Gemcitabine–Docetaxel and Pazopanib Therapy: A Case Report

Primary splenic leiomyosarcoma (PSL) is an exceptionally rare malignancy, and therapeutic guidance is limited to individual case reports. We describe a patient with disseminated PSL who achieved prolonged disease control using a sequential strategy combining cytotoxic chemotherapy and tyrosine kinase inhibitor (TKI) prolonged therapy. A 52-year-old woman presented with abdominal discomfort in the preoperative period (prior to Day 1). Magnetic resonance imaging demonstrated multiple splenic lesions with splenomegaly. Splenectomy confirmed leiomyosarcoma (French Federation of Cancer Centers Sarcoma Group (FNCLCC) grade 2; Ki-67 20-25%) with smooth muscle immunophenotype (smooth muscle actin and h-caldesmon positive). Postoperative staging with positron emission tomography/computed tomography (PET/CT) revealed diffuse metastatic disease involving the peritoneum, pleura, pericardium, and liver. She received four cycles of gemcitabine-docetaxel with partial metabolic response, followed by pazopanib (800 mg daily) as maintenance. After radiographic relapse, gemcitabine-docetaxel was reintroduced for four additional cycles. Overall, the initial response was followed by seven months of stable disease on pazopanib; after re-induction, the final documented progression occurred around Day 540. This case suggests that a cytotoxic-to-TKI sequential strategy may be feasible in disseminated PSL and was associated with prolonged disease control in this patient. Given the rarity of PSL, systematic case reporting and, when feasible, molecular characterization may help refine future management.