History: A 47-year-old woman presented to an orthopedist for evaluation of chronic pain of her left knee for the past two to three years.
病史：47歲女性，左膝慢性疼痛2-3年。 Radiographs of the left knee were obtained. Frontal, lateral, and sunrise views are shown below. 左膝平片（正側位、髕骨軸位） 
MR imagesAn MRI exam of the left knee was subsequently performed. Axial T1-weighted, fat-saturated (FS) T2-weighted, gradient-recalled echo (GRE), coronal T1-weighted, sagittal and axial proton density FS, FS T1-weighted precontrast, axial FS T1-weighted postcontrast, and sagittal FS T1-weighted postcontrast images are shown below. 隨后行左膝MR掃描，各序列圖像如下所示。 
Findings
Radiographs: There is no acute osseous abnormality. There is no radiopaque foreign body, joint effusion, or soft-tissue swelling. There is mild tricompartmental osteoarthritis. MRI: There are imaging findings of diffuse pigmented villonodular synovitis extending into the joint recesses and also extending into a moderate-sized popliteal cyst.
影像表現(xiàn)：
Differential diagnosis 鑒別診斷： 色素沉著絨毛結節(jié)性滑膜炎 痛風 血友病性關節(jié)病 淀粉樣變 滑膜軟骨瘤病
Diagnosis: Pigmented villonodular synovitis 診斷：色素沉著絨毛結節(jié)性滑膜炎
Key pointsPigmented villonodular synovitis (PVNS)
Pathophysiology 病理生理學 Pigmented villonodular synovitis refers to a rare, benign proliferative condition involving joint synovial membranes, bursae, and/or tendons. 色素絨毛結節(jié)性滑膜炎是指涉及關節(jié)滑膜，粘液囊和/或肌腱的一種罕見的良性增殖性病變。 Localized: Most common form and typically extra-articular (PVNB and GCTTS). 局限性：最常見的表現(xiàn)，典型的在關節(jié)外（PVNB和GCTTS）。 Diffuse: Most common form of intra-articular disease. However, localized intra-articular involvement also has been described. 彌漫性：關節(jié)內病變的最常見形式。 然而也可表現(xiàn)為局部的關節(jié)內受累。
Referred to as pigmented villonodular bursitis (PVNB) when in the bursa and giant cell tumor of the tendon sheath (GCTTS) when involving a tendon sheath. 當在滑液囊內，稱為色素絨毛結節(jié)性滑囊炎（PVNB）；當累及腱鞘時，為腱鞘巨細胞瘤（GCTTS）。 The condition is divided into localized and diffuse forms. 可分為局灶性和彌散性。
Etiology is unknown, but cytogenetic abnormalities and autonomous growth suggest a likely neoplastic process. 病因尚不清楚，但細胞遺傳學異常和自主生長提示其可能是一個腫瘤進程。
The abnormal synovium is predisposed to hemorrhage with trauma, leading to repeated hemorrhagic effusions and resulting in nodular formation and iron deposition in the synovium. 異常滑膜傾向于伴有外傷的出血，導致反復出血性滲出并導致滑膜中的結節(jié)形成和鐵沉積。 It is most commonly monoarticular (approximately 70% of cases) and affecting large synovial surfaces. Most common locations for intra-articular PVNS: knee > ankle > hip > shoulder > elbow. 通常是單關節(jié)發(fā)?。ù蠹s70％的病例）并影響大的滑膜表面。關節(jié)內PVNS最常見的發(fā)病部位：膝>踝>髖>肩>肘。 PVNS is rare in the pediatric population, but it is more frequently polyarticular when seen. PVNS在兒童罕見，但當發(fā)生時常表現(xiàn)為多關節(jié)。 If left untreated, the disease will lead to repeated hemorrhage and proliferation, leading to joint destruction. 如果不及時治療，該疾病將導致反復出血和增殖，從而導致關節(jié)破壞。 Malignant transformation is rare and can occur de novo or be associated with recurrent disease. Prevalence is approximately 3% of cases. 惡變非常罕見，可復發(fā)，其發(fā)生率約為3％。
Epidemiology 流行病學 Annual incidence is estimated at 9.2 (extra-articular) and 1.8 (intra-articular) cases per 1 million population. 每百萬人口的年發(fā)病率約為9.2（關節(jié)外）和1.8（關節(jié)內）。 The condition accounts for 5% of all primary soft-tissue “tumors.' 占所有原發(fā)性軟組織“腫瘤”的5%。 Intra-articular PVNS has a wide range of age of presentation. 關節(jié)內PVNS的發(fā)病年齡較廣。 Giant cell tumor of tendon sheaths: 腱鞘巨細胞瘤 Most commonly occurs between 30 and 50 years. 最多見于30-50歲。 There is no sex predilection. 沒有性別偏好。 It is the second most common soft-tissue mass of the hand. 是第二常見的手部軟組織腫物。
Clinical presentation 臨床表現(xiàn) Patients present with pain, swelling, and limited range of motion of the involved joint.患者可出現(xiàn)疼痛，腫脹和受累關節(jié)運動受限。 Effusion is typically grossly chocolate brown in color and may reaccumulate rapidly.滲出物通常呈巧克力色，可迅速重新累積。 Symptoms are usually present for many months before the diagnosis is made. 在診斷之前，癥狀通常會持續(xù)數(shù)月。
Imaging features 影像表現(xiàn)
Radiographs: 平片 PVNS: May appear normal. 可表現(xiàn)正常。 May see a joint effusion. 可見關節(jié)積液。 Can see erosions of bone on both sides of the joint, but the joint space will typically remain unaffected. 可見關節(jié)兩側的骨侵蝕，但關節(jié)間隙通常不受影響。 Normal bone density and preserved cartilage are seen until late stages of involvement. 直到病變晚期，仍可見正常的骨密度和持續(xù)存在的軟骨。 Calcification is typically not present. 通常不存在鈣化。
GCTTS:
CT：
May see large subchondral cysts. 可見較大的軟骨下囊腫。 Can see effusion and associated soft-tissue masses. 可見關節(jié)積液及軟組織腫物。 Hypertrophic synovium may demonstrate increased attenuation secondary to hemosiderin deposition. 肥厚的滑膜可因含鐵血黃素沉積而表現(xiàn)為密度增加。 Synovium enhances after contrast administration. 增強后滑膜有強化。 Calcification is typically not present. 一般無鈣化。 Can see erosions of bone on both sides of the joint, particularly in less capacious joints such as the hip. 可見關節(jié)兩側的骨侵蝕，尤其在髖關節(jié)等容積較小的關節(jié)中。
MRI： T1-weighted imaging: Appears with homogeneously low to intermediate signal. T1WI：表現(xiàn)為均勻的低至等信號。
T2-weighted/fluid-sensitive sequences: Appears with predominantly low to intermediate signal. May see some areas of high signal due to joint fluid or inflamed synovium. T2WI（液體敏感序列）：主要表現(xiàn)為低至等信號，由于關節(jié)積液或滑膜炎癥可見一些高信號區(qū)域。 GRE: Blooming is seen due to the presence of hemosiderin. GRE：由于含鐵血黃素存在而呈低信號。 Postcontrast imaging: Moderate to marked inhomogeneous enhancement is seen. 增強掃描：可見中等至明顯不均質強化。 May increase conspicuity for assessment of lesion extent. 可提高病變程度評估 的顯著性。
Treatment 治療 Requires resection with complete synovectomy. 需要行完全滑膜切除。 Incomplete resection has a high recurrence rate; overall recurrence rate is 20% to 50%. 不完全切除將有較高的復發(fā)率，總的復發(fā)率在20%-50%。 May require an open surgical procedure, as an arthroscopic technique may not reach some lesions. 需要行開放式手術，因為關節(jié)鏡技術可能無法達到某些病變。 Adjuvant treat is often recommended with radiation and sometimes with intra-articular injection of yttrium-90. 輔助治療通常建議使用放療，有時還需要關節(jié)內注射釔-90。 Medical therapy is being investigated. 藥物治療還在研究中。 Refractory cases may require arthroplasty or arthrodesis. 難治性病例可能需要關節(jié)成形術或關節(jié)固定術。
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