CSF2 and juvenile myelomonocytic leukemia: Bacterial [69] and viral (e.g., Epstein–Barr virus [70], cytomegalovirus [71], and herpesvirus 6 [72]) infections can mimic the clinical and laboratory findings of JMML in infants, including fever, splenomegaly, leukocytosis with monocytosis, hypersensitivity to GM-CSF, and STAT5 hyperphosphorylation.