Table 1. Summary of Reported Regional Pathophysiological Mechanisms of Acne from Included Studies

Region	Traditional-medicine pathophysiology	Western-medicine pathophysiology	Reference number
Forehead	Heart(心)Heart fire flaring upward(心火上炎)Excess heat in the blood(血熱內盛)Lung wind-heat(肺經風熱)	T-zone*-High density of sebaceous glands-Sebum secretion and bacteria-Sebum and pH-Adolescent lesion concentrationO-zone(include perioral)	[2,4,7,8,12–19]
Nose	Spleen(脾)Damp-heat in spleen and stomach(脾胃濕熱)Stomach meridian(胃經)		[2,4,5,7,8,12,15–19,31]
Left cheek	Liver(肝)Lung(肺)†Liver qi stagnatio(肝氣鬱結)	Inconsistent T/U-zone classification	[2,4,18]
Right cheek	Lung(肺)Lung heat(肺熱)Excess heat in stomach and large intestine(胃大腸實熱)		[2,4,17,18, 20]
Chin/Jawline	Kidney(腎)Kidney yin deficiency(腎陰虛)Liver–Kidney deficiency(肝腎不足)Chong-Ren disharmony(沖任失調)Spleen–Kidney yang deficiency(脾腎陽虛),Foot Shaoyin Kidney meridian(足少陰腎經)Foot Shaoyang Gallbladder meridian(足少陽膽經)Qi-stagnation constitution(氣鬱體質)Phlegm-damp constitution(痰濕體質)	Representative predilection site of adult-acneHormonal acneFemale acneMenstrual cycle fluctuationMenstrual irregularityPCOS associationHPA-axis related Stress effect	[2,4,7,8,12, 13,18–25,30]

Forehead and nose were analyzed together as the T-zone in several studies; however, distinct pathophysiological interpretations for each subregion were not provided
Both cheeks were assigned to Lung.