CSF1 and lymphoma: Although elevated M‐CSF serum levels have been reported in HL patients, and HL cells were found to be M‐CSF‐positive by immunohistochemistry, the measured M‐CSF amounts in the lymphoma‐CM in vitro and the differences in Mφ counts and phenotype indicate the involvement of additional factors during HL‐specific Mφ differentiation (Casagrande et al., 2019; Kowalska et al., 2012; Zheng et al., 1999).