Jing N, Bai QX, Lu J. Localized Pigmented Villonodular Synovitis of the Knee Joint: A Case Report and Literature Review

Case Report

Austin J Clin Case Rep. 2024; 11(7): 1345.

Localized Pigmented Villonodular Synovitis of the Knee Joint: A Case Report and Literature Review

Niu Jing, MD¹; Qiao Xu Bai, MD²; Jike Lu, MD, PhD¹*

¹Departments of Orthopaedics, Beijing United Family Hospital, No 2 Jiangtai Road, Chaoyang District, Beijing, 10016, China.

²Departments of Orthopaedics and Pathology, Beijing United Family Hospital, No 2 Jiangtai Road, Chaoyang District, Beijing, 10016, China.

*Corresponding author: Jike Lu, Department of orthopedic Surgery, Beijing united family hospital, Beijing China. Email: jike.lu@ufh.com.cn

Received: November 18, 2024; Accepted: December 10, 2024; Published: December 17, 2024

Abstract

The incidence rate of PVNS, which is synovium tissue as nodules or pedunculated masses, is low however, the localized type is even less. We reported a case of the unusual properties of LPVNS located in the knee.

A 32-year-old man presented to our clinic with pain and mechanic symptoms in his right knee. Magnetic resonance imaging (MRI) showed an intra-articular mass in the infrapatellar area of the knee adjacent to the Hoffa fat pad close to femoral trochlea groove. The mass was hypo intense in the T1 sequence and heterogeneously hypointense in the T2 sequence as well, which was considered as a local type of tenosynovial giant cell tumor (LPVNS). Excision was carefully performed without penetrating the tumor. The gross appearance of the tumor was yellow-reddish and brown in color. Histopathologic examination revealed pigmented villonodular synovitis of the local type.

Localized Pigmented Villonodular Synovitis (LPVNS) is a very rare disease and it is silent and insidious, symptoms are non-specific, nevertheless, differentiation diagnosis should be keeping this entity in mind.

Even though the LPVNS of the knee is an uncommon intra-articular presenttion, overlook this lesion based on imaging findings is an import approach for diagnosis of LPVNS, and arthroscopy assisted excision is an option for management of the LPVNS if doing it appropriately.

Keywords: Pigmented Villonodular Synovitis; Synovial Tumor-like Lesions; Knee pain; Intra-articular Mass

Introduction

Jaffe et al coined the term “PVNS” for the first time in 1941 [1]. Pigmented Villonodular Synovitis (PVNS) most frequently occurs in the knee as a proliferative phenomenon that involves the synovial membrane [2,3]. It is considered a benign lesion of unknown origins. Some authors propose that it is probably caused by inflammation, trauma, toxins, allergies, clonal chromosomal abnormalities, or aneuploidy [4,5].

The disease can be classified into two types: diffuse and localized. The diffuse form (DPVNS), as the name indicates, attacks practically the entire synovial cellular membrane of the affected joint. The localized form (LPVNS) is characterized as a nodule or pedunculated mass. This type is generally a solitary mass of pedunculated or, much less frequently, 2–3 nodules yellowish-brown in color [6-10]. When LPVNS affects the knee, it is generally located in the anterior compartment [6,7].

The incidence rate of PVNS is estimated to be 1.8 per million people—the localized type is just one-quarter of that [11].

Significant swelling with pain at the joint is a characteristic presentation of the patient complaints. Heat and tenderness at and near the joint, limited movement of the joint, locking or catching of the joint popping of the joint, hemarthrosis of blood collects in the joint are common clinical presentations.

Approximately 85% of PVNS occurs in the fingers, whereas 12% of the tumors are located in the knee, elbow, hip, and ankle [12]. PVNS can occur at any age, although it is most common between the ages of 30 and 50, with a female preponderance of 2:1 [13].

Case Report

A 32-year-old man entered our clinic with pain and discomfort in his right knee. The pain had persisted for 3 months, after fell over and twisted his right knee while running. He was recalled that the knee cap was subluxed laterally but reduced spontaneously. He complained the knee was not functioning properly due to catching locking symptoms and restriction of the range of movements. He was difficult to climb stairs and to do squatting activity. Physical examination revealed a painful knee with large effusion of the joint and significantly reduced Range of Movement (ROM), the flexion of the knee was hardly reaching 90 degrees, and Fixed Flexion Deformity (FFD) was 25 degrees. There was pain in flexion and extension, while the patellar tendon was contracted in extension. Lateral and medial McMurray tests, Lachman test was negative. Routine laboratory tests including ESR, CRP, and serum uric acid levels were normal.

Radiographs showed no bony pathology (Figure 1). Magnetic Resonance Imaging (MRI) showed an intra-articular mass of 5× 3 × 1.5 cm in the infrapatellar region of the knee adjacent to the Hoffafat pad. The mass was hypointense in the T1 sequence (Figure 2) and heterogeneously low or intermediate signal in the T2 sequence (Figure 3), which was considered a LPVNS. Based on these findings, arthroscopy-assisted excision of the mass was decided. Under general anesthesia, arthroscopically surgery was performed. Standard portal stabbing incisions were made but medial portal incision was extended longer as required for removal of a large 5 cm x3.5 cm x2cm PVNS mass that is characterized by a single discrete or pedunculated nodule (Figure 5). Removal of all affected parts of the synovium is critical for preventing recurrence. The joint effusion was drained and send for crystal exam in laboratory. Lateral femoral condyle and lateral facet patellar chondral lesion of grade III to IV was seen and abrased with a chondrotone for chondroplasty. A hypoplastic trochlea was identified arthroscopically. The patellar was sitting laterally with subluxation, subsequently lateral retinaculum arthroscopically release was performed with a Radiofrequency (RF). The patellar femoral tracking was checked which was back to normal after lateral release, therefore, no MPFL reconstruction was performed.

Figure 1: The lateral radiograph of the knee demonstrates no bony pathology intra-articularly but he had previous patellar dislocations, patellofemoral joint instability exists with patellar shifting and tilting laterally with medial facet old fractured fragment indicating his localized PVNS might be related to his knee injuries and recurrently subluxation patella.

    
    
    Figure 1: The lateral radiograph of the knee demonstrates no bony pathology
intra-articularly but he had previous patellar dislocations, patellofemoral joint
instability exists with patellar shifting and tilting laterally with medial facet old
fractured fragment indicating his localized PVNS might be related to his knee
injuries and recurrently subluxation patella.

Figure 2: Sagittal T1-weighted image, arrow shows hypointense mass located in Hoffa fat pad (A); Axial view showing the mass sitting close to inferior trochlea groove (B).

    
    
    Figure 2: Sagittal T1-weighted image, arrow shows hypointense mass
located in Hoffa fat pad (A); Axial view showing the mass sitting close to
inferior trochlea groove (B).

Localized Pigmented Villonodular Synovitis of the Knee Joint: A Case Report and Literature Review

Abstract

Introduction

Case Report

Discussion

References