Wilms Tumor and Paraneoplastic Syndromes: Unusual Presentation With Acquired von Willebrand Disease, Polycythemia and Hyperviscosity-A Comprehensive Case Report and Literature Reviews.

A 10-month-old child presenting with renal tumor with polycythemia, acquired von Willebrand disease, and elevated serum hyaluronic acid, leading to a diagnosis of Wilms tumor. Laboratory profile showed elevated levels of hemoglobin and hematocrit, prolonged aPTT, and high levels of hyaluronic acid and erythropoietin, which normalized after chemotherapy and tumor resection. She had a complete response and has remained in remission. Paraneoplastic syndromes are rare manifestations of Wilms tumor (WT). The simultaneous occurrence of distinct types, as demonstrated in this report (polycythemia, hyperviscosity, and coagulopathy), has not been previously reported. This unique presentation poses a challenge for both diagnostic and clinical management.