Introduction
PVNS are rare, locally aggressive, typically benign neoplasms of joints, bursae, and tendon sheaths.1, 2, 3 Pigmented Villonodular Synovitis is a locally aggressive neoplastic synovial disease (not a true neoplasm) characterized by joint effusions, expansion of the synovium, and bony erosions. The condition usually presents in patients between 30 and 40 years old with recurrent atraumatic knee hemarthrosis subsequently leading to pain and restricted movements of joint. Another name is the Tenosynovial giant cell tumor, with giant cell tumor of tendon sheath (GCTTS) being the localized form of the diffuse type PVNS.4, 5 Uncertain etiology involves inflammation, trauma, toxin, allergy, clonal chromosomal abnormalities and aneuploidy. We report a case of localised asymptomatic PVNS incidentally found at the popliteal fossa.
Case Report
32-year-old male, a professional footballer had a history of twisting injury while playing and c/o pain, swelling and instability over the right knee. The patient wasn’t able to complete his game and had to be substituted. The pain was sudden in onset, progressive in nature and non-radiating. The pain was associated with a massive effusion of the knee within an hour. The patient wasn’t able to bear weight on the affected limb and gross restriction of movements at the knee was seen. He was advised MRI, following which he was suggested for surgery which he refused. He presented to us after 1 month of conservative treatment. On examination of right knee, ROM was 0-90 with Lachmann test Mushy, Pivot shift was nil & Valgus/ Varus stress test negative. McMurray test was Positive. MRI was suggestive of a Complete Tear of ACL and Bucket handle tear of Medial meniscus with a Focal Nodular Hypertrophy at the popliteal fossa 9 (Figure 1, Figure 2, Figure 3).
The patient was taken up for ACL reconstruction using Ipsilateral Hamstrings with Medial Meniscus tear excision and balancing with Arthroscopic excisional Biopsy of the Nodular mass (3x2cms) at the popliteal fossa were taken with respect to its principles and sent for HPE (Figure 4). The biopsy turned out to be a Tenosynovial Giant Cell Tumor – Localised type.
Discussion
PVNS may occur at any age but mostly at ages between 30 and 50, with a 2:1 female predominance. The usual presentation is knee swelling, usually slowly progressive with zero to mild pain, and a rare history of trauma.6, 7 Plain radiography is usually free.7 The MRI is the gold standard to diagnose the masses in or around the knee joint.8 Local excision with arthroscopy or arthrotomy is the treatment of choice. Local recurrence was reported to be 10–20% with the reason of inadequate primary resection. PVNS is usually associated with recurrent atraumatic hemarthrosis leading to swelling, restriction of movements, and pain. Our case study showed peculiar features of asymptomatic PVNS that was completely incidental. They are either diffuse (extra-articular) or localised (intra-articular) in origin. 20% of cases are local and 80% are diffuse.9 Although the most common site of a localised tumor is the anterior aspect of the knee i.e. patellofemoral compartment at the infrapatellar fat pad; our patient showed a rare occurrence at the posterior aspect of the knee i.e. popliteal fossa.
There are very few studies reporting asymptomatic PVNS at the posterior aspect of knee. Various treatment modalities are available for management of PVNS. Surgical options include synovectomy either by arthrotomy or arthroscopy.
In case series of Shekhar A et al documented 10 patients (7 males and 3 females). These patients had symptoms of pain, locking or swelling before diagnosis. All the patients underwent arthroscopic synovectomy. 10
In Dines’ series of Localised PVNS, 3 of 26 patients in their study had the tumor localized in the popliteal fossa, but all were symptomatic. 11
Samir H. Shah et al documented Bilateral localised PVNS which was again symptomatic.12
Malignant tumors, such as synovial sarcoma and benign soft tissue tumors, should be kept in mind in differential diagnosis. Synovial sarcoma lesions usually create reaction and disorders in the adjacent bone. As in our case, benign tumors usually do not cause a reaction in the adjacent bone. Tenosynovial giant cell tumors localized in the knee joint are very rare; they should be kept in mind in the differential diagnosis. MRI is helpful in diagnosis and marginal excision is sufficient in the treatment. Localised PVNS of the knee is amenable to complete resection, and achieving total macroscopic disease removal is crucial. The posterior compartment of the knee is one area which is perhaps better approached arthroscopically than by open surgery, in view of the complex anatomy and vicinity of neurovascular structures and lesser morbidity with the minimally invasive approach. PVNS is a rare disease entity, and posterior location of it is even more uncommon and only sparsely described in the literature.
