Abstract：
Granular C3 dermatosis (GCD) is characterized by bullous, erythematous, and eczematous skin lesions similar to dermatitis herpetiformis, and granular deposition of complement C3 and C5b-9 along the epidermal basement membrane zone (BMZ) by direct immunofluorescence (IF). Here, we present two cases of GCD with different clinical features. Case 1, a 49-year-old man, showed pruritic blisters and erythema of the extremities. Case 2, a 53-year-old woman, showed severely pruritic papules, erythema, and erosions on the entire body with scattered blisters, mainly on the lower extremities. Both patients showed mild eosinophilia on blood tests, subepidermal blisters and prominent eosinophilic infiltration in the upper dermis on histopathological examination, and granular BMZ deposition of C3, but not of immunoglobulins or other complement components, on direct IF. No circulating autoantibodies were detected on enzyme-linked immunosorbent assays, chemiluminescent enzyme immunoassays, indirect IF using 1 mol/L NaCl-split normal human skin, or immunoblotting. Diagnosis of GCD was made in both cases. Case 1 was successfully treated with topical steroids, oral minocycline, and nicotinamide without any recurrence of symptoms. Case 2 was treated with oral steroids and showed remarkable improvement, although mild pruritic papules remained. We reviewed 30 reported GCD cases, including the two cases presented here, since Hashimoto et al. first described GCD in 2016. GCD should be more widely recognized, and further accumulation and validation of cases are required.
摘要：
颗粒状C3皮肤病（GCD）的特征是大疱性，红斑,和湿疹性皮肤病变类似于疱疹样皮炎，并通过直接免疫荧光（IF）沿表皮基底膜区（BMZ）颗粒状沉积补体C3和C5b-9。这里,我们介绍了2例具有不同临床特征的GCD。案例1，一个49岁的男人，显示瘙痒性水疱和四肢红斑。案例2，一个53岁的女人，表现出严重的瘙痒性丘疹,红斑,和整个身体上的侵蚀，散落的水泡，主要在下肢。两名患者在血液检查中都显示出轻度嗜酸性粒细胞增多,组织病理学检查上真皮表皮下水疱和明显的嗜酸性粒细胞浸润，和C3颗粒BMZ沉积，但不包括免疫球蛋白或其他补体成分，直接如果。在酶联免疫吸附试验中未检测到循环自身抗体，化学发光酶免疫测定，使用1mol/LNaCl分裂的正常人皮肤的间接IF，或者免疫印迹.两种情况均诊断为GCD。病例1用局部类固醇成功治疗，口服米诺环素，和烟酰胺没有任何复发的症状。病例2采用口服类固醇治疗，并显示出显着改善，尽管仍有轻度瘙痒丘疹。我们回顾了30例报告的GCD病例，包括这里介绍的两个案例，自从桥本等人。2016年首次描述GCD。GCD应该得到更广泛的认可，需要进一步积累和验证案例。
