Divison of Infection Control and Prevention, Osaka University Hospital, Japan.
Department of Orthopaedic Surgery, Graduate School of Medicine, Osaka University, Japan.
J Infect Chemother. 2020 Feb;26(2):261-264. doi: 10.1016/j.jiac.2019.07.015. Epub 2019 Aug 16.
Mycobacterium kansasii is one of the major non-tuberculous mycobacteria species that typically cause pulmonary diseases. M. kansasii is known to cause septic arthritis as an extrapulmonary disease in immunosuppressed patients or chronic skin disease. Herein, we present a case of M. kansasii arthritis involving the elbow of an immunocompetent patient, which was initially suspected to be a soft-tissue tumor. A 70-year-old man presented with a swollen left elbow that had progressed for 18 months with deteriorating arthralgia and limited range of motion. Magnetic resonance imaging revealed filling of the intra-articular space of the elbow and surrounding of the radial head with a soft tissue mass with mixed signal intensity. Initial incisional biopsy was performed via the lateral approach to the elbow joint, and pathological examination of the mass did not reveal any evidence of malignancy. One year after the first operation, arthroscopic surgery was performed to excise the mass following the recurrence of swelling and limited function of the elbow. Pathological examination of the resected synovium revealed epithelioid granulomas containing a multinucleated giant cell and inflammatory cell infiltration, characteristic of mycobacterial infection. M. kansasii was cultured after 2 weeks of incubation of the synovial sample. He experienced full resolution of the swelling and limited function following a combination of synovectomy and multidrug antimycobacterial treatment (rifampin 600 mg/day, clarithromycin 800 mg/day, and ethambutol 750 mg/day). This case highlights the need to consider this rare infection in the differential diagnosis of intra-articular soft tissue tumor-like lesions even in immunocompetent patients.
堪萨斯分枝杆菌是主要的非结核分枝杆菌之一，通常会导致肺部疾病。堪萨斯分枝杆菌已知会引起免疫抑制患者的败血症性关节炎或慢性皮肤病等肺外疾病。在此，我们报告了一例累及免疫正常患者肘部的堪萨斯分枝杆菌关节炎病例，该病例最初被怀疑为软组织肿瘤。一名 70 岁男性因左侧肘部肿胀就诊，该肿胀已进展 18 个月，伴有进行性关节痛和活动范围受限。磁共振成像显示肘部关节腔内充满了软组织肿块，伴有混合信号强度，周围环绕着桡骨头。最初通过外侧入路对肘关节进行了切开活检，对肿块的病理检查未发现任何恶性证据。第一次手术后 1 年，由于肿胀和肘部功能受限复发，进行了关节镜手术切除肿块。切除的滑膜的病理检查显示含有多核巨细胞的上皮样肉芽肿和炎症细胞浸润，这是分枝杆菌感染的特征。滑膜样本孵育 2 周后培养出堪萨斯分枝杆菌。他接受滑膜切除术和多药抗分枝杆菌治疗（利福平 600mg/天、克拉霉素 800mg/天和乙胺丁醇 750mg/天）后，肿胀和功能受限完全缓解。该病例强调了即使在免疫正常的患者中，也需要考虑这种罕见感染在关节内类似软组织肿瘤病变的鉴别诊断中的作用。
