Figure 1: Schematic representation of study design. The collected sera from occupational medicamentosa-like dermatitis induced by trichloroethylene (OMLDT) patients, TCE contacts and healthy controls were purified by a weak cation exchange magnetic beads (MB-WCX) chromatography. The serum proteomic profiles were analyzed by matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS) and ClinProTools. After the statistical analysis by ClinProTools, twenty-one significantly different peaks which were alike between two models were selected and further validated in different periods of seven typical OMLDT patients. Those peaks were defined as specific peaks of OMLDT. Then we calculated the peak area probability of these specific peaks in each period and analyzed the dynamic change of peak area probability distribution in different periods of OMLDT patients. Finally, m/z 4109Da characteristic peak may be the latent serum biomarker of OMLDT.