Tocilizumab as a novel bridging therapy for surgery in dedifferentiated liposarcoma complicated by paraneoplastic leukemoid reaction, severe anemia, and thrombocytopenia: a case report.

BACKGROUND: Dedifferentiated liposarcoma (DDLPS) is a malignant mesenchymal tumor. While paraneoplastic leukemoid reaction (PLR) has been sporadically reported in DDLPS, its coexistence with severe anemia and thrombocytopenia, constituting a severe cytokine release syndrome (CRS), is exceedingly rare and presents a significant diagnostic and therapeutic challenge.

CASE PRESENTATION: A 56-year-old male with recurrent retroperitoneal well-differentiated liposarcoma presented with high fever, profound leukocytosis (WBC up to 43×109/L), severe anemia (Hb 30 g/L), and thrombocytopenia (platelets 10×109/L), which precluded immediate surgery. Extensive workup ruled out infection and hematological malignancies. The clinical picture was consistent with a tumor-induced CRS, evidenced by markedly elevated interleukin-6 (IL-6) and C-reactive protein (CRP). Following a multidisciplinary discussion, the patient received intravenous tocilizumab (an IL-6 receptor antagonist) and methylprednisolone. His fever resolved rapidly, and hematological parameters improved significantly, facilitating successful tumor resection. Postoperative pathology confirmed DDLPS. All paraneoplastic symptoms and laboratory abnormalities normalized after surgery. However, at the second follow-up, tumor recurrence was observed along with a marked elevation of the WBC, which again decreased following the subsequent surgical resection.

CONCLUSION: This case highlights that DDLPS can trigger CRS, which manifests with clinical features mimicking severe infection and leading to critical cytopenias that complicate surgical management. IL-6 pathway blockade with agents such as tocilizumab may be an effective bridging therapy to stabilize the systemic inflammatory state and create a safe window for surgical intervention.