Supplementary Material for: The Cystic Sponge Anus

Introduction:
A peculiar spongy appearance of the perianal skin was observed a patient who underwent wide excision surgery for inguinal and gluteal Hidradenitis Suppurativa (HS).

Case Presentation:
This peculiar appearance was observed in a 62 year old male patient. It included multiple orifices and cavities forming the spongy aspect of the perianal skin with multiple cysts and giant comedones. The perianal lesions were asymptomatic and the patient had never received any perianal treatment for the comedones or cysts. Histopathology was performed and demonstrated dilated hair follicles with flaky keratin and loose hair shafts in the center. The spongy appearance was most likely the result of spontaneous shedding of the cystic contents.

Conclusion:
We suspect that the ‘Cystic Sponge Anus’ might be associated with HS, smoking, the male gender, and may yet be another expression of an occlusive follicular disease. Future studies will be needed to clarify the prevalence and comorbidities of the ‘Cystic Sponge Anus’.

引言：
在一例接受腹股沟及臀部化脓性汗腺炎（Hidradenitis Suppurativa, HS）广泛切除术的患者中，观察到肛周皮肤出现特殊的海绵样外观。

病例报告：
该特殊外观见于一位62岁男性患者。患者肛周皮肤可见多发孔隙与腔隙，形成海绵样表现，同时伴有多发囊肿及巨大粉刺（comedones）。肛周病变无自觉症状，患者此前未因粉刺或囊肿接受过肛周相关治疗。组织病理学检查显示，毛囊扩张，中央可见片状角化物及松动的毛干。该海绵样外观极有可能是囊内容物自发排出所致。

结论：
我们推测“囊性海绵样肛”可能与HS、吸烟及男性性别相关，或许是闭塞性毛囊疾病的又一种表现形式。未来仍需开展相关研究以明确“囊性海绵样肛”的患病率及合并症情况。