Previous studies revealed similar VAFs of CH mutations (0.45 < VAF < 0.55) in pathogenic cells in Erdheim–Chester disease [23,34], bone marrow cells of patients with myelodysplastic/myeloproliferative neoplasms [35], and tumor cells of Epstein–Barr virus-positive diffuse large B cell lymphoma [36]. This evidence concerns the gene C4B and myeloproliferative neoplasm.