Supplementary Material for: Granulomatous pigmented purpuric dermatosis (GPPD) in a patient with (inactive) myasthenia gravis : Case report and review of the literature

Granulomatous pigmented purpuric dermatosis (GPPD) is a rare histologic variant of pigmented purpuric dermatosis (PPD) characterized by dermal histiocyte-rich interstitial infiltration with or without granuloma formation in addition to the other typical features of PPD. GPPD was previously observed more frequently to affect Asians and was reported to be associated with dyslipidemia. However, our literature search of 45 documented GPPD cases revealed an increasing prevalence in Caucasians in addition to dyslipidemia and associated autoimmune diseases. To date, etiopathogenesis of GPPD is unknown, but may involve dyslipidemia, genetic and immunological factors such as autoimmune dysregulation or a sarcoidal reaction associated to with C. acnes. GPPD is usually persistent and recalcitrant to treatments. We report a case of GPPD in a 57-year-old Thai woman with underlying myasthenia gravis who presented with a pruritic eruption on both lower legs. After treatment with 0.05% clobetasol propionate cream and oral colchicine, the lesion improved with marked flattening and disappeared with residual postinflammatory hyperpigmentation. We provide a literature review of the epidemiology, etiopathogenesis, concomitant comorbidities, clinical symptoms, dermatoscopic features, and treatments of GPPD.

肉芽肿性色素性紫癜性皮肤病（Granulomatous pigmented purpuric dermatosis, GPPD）是色素性紫癜性皮肤病（pigmented purpuric dermatosis, PPD）的罕见组织学亚型，除具备PPD的其他典型特征外，还以真皮富含组织细胞的间质性浸润伴或不伴肉芽肿形成为特征。既往研究显示GPPD更常见于亚洲人群，且有报道称其与血脂异常相关。但本次对45例已报道的GPPD病例进行的文献检索发现，除血脂异常外，白种人群中的患病率亦呈上升趋势，且该病还与自身免疫性疾病相关。截至目前，GPPD的发病机制尚未明确，推测可能涉及血脂异常、遗传及免疫因素，如自身免疫失调或与痤疮丙酸杆菌（C. acnes）相关的肉样瘤样反应。GPPD通常呈持续性病程，且治疗抵抗性较强。本文报告1例合并重症肌无力（myasthenia gravis）的57岁泰国女性GPPD病例，该患者表现为双侧小腿瘙痒性皮疹。予0.05%丙酸氯倍他索乳膏外用联合口服秋水仙碱治疗后，皮损显著变平并逐渐消退，仅遗留炎症后色素沉着残留。本文同时对GPPD的流行病学、发病机制、伴随合并症、临床症状、皮肤镜特征及治疗方案进行了文献综述。