A woman in her 20s with a medical history significant for systemic lupus erythematosus (SLE) presented with tender erythematous nodules after undergoing right knee arthroscopy (Figure, A). SLE had been diagnosed ten years previously after she presented with a positive antinuclear antibody titer (most recent titer, 1:1280), arthralgias, leukopenia, oral ulcers, and a malar erythematous eruption. There was no history of discoid or tumid lupus lesions. Initially, the lesions were thought secondary to soft-tissue infection and were treated with courses of clindamycin, vancomycin, and doxycycline. Physical examination revealed poorly demarcated erythematous plaques and nodules, tender to palpation, ranging from the distal thigh to the lower leg, adjacent to arthroscopy sites. Lesions around the suture sites appeared more violaceous. A punch biopsy of the lesion was performed (Figure, B and C).

患者女性，20余岁，有显著系统性红斑狼疮（SLE）病史，右膝关节镜术后出现疼痛红斑结节（图A）。10年前发现患者抗核抗体滴度阳性（近期滴度，1:1280）、关节痛、白细胞减少、口腔溃疡和颧部红斑暴发，随后被确诊为系统性红斑狼疮。患者无盘状或肿胀性红斑病史。起初，认为皮损继发于软组织感染，随后采用克林霉素、万古霉素和多西环素进行治疗。体格检查示大腿远端到小腿部可见边界不清的红色斑块和结节，触之疼痛，毗邻关节镜手术部位。缝合部位皮损更多呈紫色。对皮损进行穿刺活检（图B和C）。