Gans Itai, Morrison Martin J, Chikwava Kudakwashe R, Wells Lawrence
Orthopedics. 2014 Mar;37(3):e313-6. doi: 10.3928/01477447-20140225-67.
The differential diagnosis for an intra-articular lesion in the knee of a pediatric patient is broad. Diagnostic considerations include pigmented villonodular synovitis (PVNS)-the most common intra-articular tumor-and a variety of both benign and malignant tumors, including lipomas, hemangiopericytomas, nodular fasciitis, parosteal osteosarcomas, and fibromyxoid sarcomas. If there is concern over possible malignant lesions, a tumor surgeon should be consulted. Precise pathologic diagnosis is ideal for identifying these enigmatic lesions and for determining the appropriate treatment plan. This article presents the case of a 13-year-old boy who presented with 1-month duration of knee pain and no history of trauma to the extremity. Physical examination revealed pain along the medial and lateral joint lines, pain with range of motion, and limited range of motion of the affected knee. Magnetic resonance imaging revealed a 3×1×3-cm lesion in the posterolateral corner that was believed to be localized PVNS. Arthroscopically, there was no evidence of PVNS, but a posterolateral soft tissue mass was found and removed, which was pathologically diagnosed as a rare, benign, intra-articular nodular fasciitis. When working with intra-articular masses, it is important to assess the likelihood of malignancy and to both consult a tumor surgeon and use the appropriate surgical tumor principles when malignancy is a concern. Additionally, the pathology team should be consulted prior to surgery and be on standby during arthroscopic evaluation of the knee to help with precise diagnosis of the intra-articular mass. Discussing the case with the pathologist with imaging studies present is helpful and often aids in the diagnosis of the lesion.
小儿患者膝关节内病变的鉴别诊断范围广泛。诊断时需考虑色素沉着绒毛结节性滑膜炎（PVNS）——最常见的关节内肿瘤——以及多种良性和恶性肿瘤，包括脂肪瘤、血管外皮细胞瘤、结节性筋膜炎、骨膜骨肉瘤和纤维黏液样肉瘤。如果担心可能存在恶性病变，应咨询肿瘤外科医生。精确的病理诊断对于识别这些疑难病变以及确定合适的治疗方案非常理想。本文介绍了一名13岁男孩的病例，该男孩膝关节疼痛持续1个月，且该肢体无外伤史。体格检查发现膝关节内外侧关节线处疼痛、活动时疼痛以及患侧膝关节活动范围受限。磁共振成像显示后外侧角有一个3×1×3厘米的病变，被认为是局限性PVNS。关节镜检查时，未发现PVNS的证据，但发现并切除了一个后外侧软组织肿块，病理诊断为罕见的良性关节内结节性筋膜炎。在处理关节内肿块时，重要的是评估恶性的可能性，当担心存在恶性情况时，既要咨询肿瘤外科医生，又要遵循适当的肿瘤手术原则。此外，术前应咨询病理团队，并在膝关节镜检查评估期间待命，以帮助精确诊断关节内肿块。在有影像学检查结果的情况下与病理学家讨论病例是有帮助的，通常有助于病变的诊断。
