Systemic contact dermatitis (SCD) is a generalized reactivation of type IV hypersensitivity skin diseases in individuals with previous sensitization after a contact allergen is administered systemically. Patients with SCD may consider their dermatitis unpredictable and recalcitrant since the causative allergens are difficult to find. If a patient has a pattern of dermatitis suggestive of SCD but fails to improve with conventional treatment, SCD should be taken into consideration. If doctors are not familiar with the presentations of SCD and the possible routes of allergen sensitization and exposure, the diagnosis of SCD may be delayed. In this work, we summarized all of the routes through which allergens can enter the body and cause SCD, including oral intake, local contact (through skin, inhalation, nasal spray and anal application), implants, and other iatrogenic or invasive routes (intravenous, intramuscular, intraarticular, and intravesicular). This will provide a comprehensive reference for the clinicians to identify the culprit of SCD.

全身性接触性皮炎 (SCD) 是在全身施用接触性过敏原后，先前过敏的个体中 IV 型超敏性皮肤病的全身性再激活。SCD 患者可能认为他们的皮炎是不可预测的和顽固的，因为难以找到致病过敏原。如果患者的皮炎模式提示 SCD，但常规治疗未能改善，则应考虑 SCD。如果医生不熟悉 SCD 的表现以及过敏原致敏和暴露的可能途径，SCD 的诊断可能会延迟。在这项工作中，我们总结了过敏原进入体内并导致 SCD 的所有途径，包括口服、局部接触（通过皮肤、吸入、鼻腔喷雾和肛门应用）、植入物、和其他医源性或侵入性途径（静脉内、肌肉内、关节内和囊内）。这将为临床医生识别SCD的罪魁祸首提供全面的参考。