Splenomegaly — Massive in Tropical Disease

A 42-year-old man from Bihar presents with a 3-month history of progressive abdominal distension and left upper quadrant fullness. On examination, the structure marked **A** (visible LUQ splenomegaly) extends well below the left costal margin and crosses the midline. He reports fever, weight loss, and darkening of his skin. Laboratory investigations show pancytopenia (Hb 8.2 g/dL, WBC 2.8 × 10⁹/L, platelets 95 × 10⁹/L) and elevated LDH. A rapid immunochromatographic test for rK39 antigen is positive. Which of the following is the most appropriate definitive treatment for this patient's condition?