Volumetric splenomegaly in patients with essential thrombocythemia and prefibrotic/early primary myelofibrosis

Non-palpable, volumetric splenomegaly at diagnosis was evaluated using computed tomography in patients with essential thrombocythemia (ET) and prefibrotic/early primary myelofibrosis (pre-PMF) based on 2016 World Health Organization guidelines. Each patient’s spleen volume was adjusted for their age and body surface area. The degree of splenomegaly was classified as no, borderline volumetric, overt volumetric, or palpable splenomegaly. Seventy-six patients with ET (median age, 62.5 years) and 19 patients with pre-PMF (median age, 65 years) were followed up for a median of 2.4 years (range 0.1–17.6 years) and 4.2 years (range 0.2–19.6 years), respectively. Spleen volume was significantly greater in pre-PMF patients than in ET patients (377.9 ± 92.2 cm 3 vs. 224.9 ± 115.2 cm 3 , P