皮下结节病

皮下结节病是一种少见的结节病皮肤损害，病因不明，免疫反应是主要发病机制。临床表现为四肢的无痛性皮下结节，多伴有双侧肺门淋巴结肿大等系统损害。组织病理表现为皮下脂肪层和真皮深层的非干酪性上皮细胞样结节，周围有结缔组织包裹，结节周围少量淋巴细胞浸润。结合组织病理检查和影像学检查可明确诊断。糖皮质激素是首选治疗方法。肿瘤坏死因子-α拮抗剂、免疫抑制剂和光动力治疗也是可供选择的治疗手段之一。

Subcutaneous sarcoidosis

Subcutaneous sarcoidosis is an uncommon kind of sarcoidosis with undetermined etiology. Immune reaction is regarded as the main pathogenesis. The predominant clinical manifestation is painless nodules in extremities together with systemic diseases, such as bihilar lymphadenopathy. Histopathologically, it is characterized by non-caseating epithelioid grannuloma encapsulated with connective tissue and surrounded by a sparse lymphocytic infiltrate in the subcutaneous tissue and deep dermis. The diagnosis of subcutaneous sarcoidosis can be confirmed by the combination of radiology and biopsy. Topical and systemic corticosteroids are the first-line therapy. Other treatment options include tumor necrosis factor （TNF）-α antagonists, immunosuppressive drugs and photodynamic therapy.