NGF and cutaneous mastocytosis: In addition to the detected lower levels of NGF, BDNF and PGE2 among EM patients compared to controls, NGF was the only biomarker in our study that showed significantly different (i.e., lower) serum levels in EM patients than that of CM patients, while none of the remaining three biomarkers investigated in our case control study were able to discern between CM and EM (although difference in PGE2 levels between EM and CM patients trended towards significance).