Localized pigmented villonodular synovitis (PVNS) is a rare, benign, proliferative disease of the synovial membrane of joints & can mimic other pathology like loose body, meniscal tear & soft tissue sarcomas etc. Diagnosis of these lesions can be difficult clinically & magnetic resonance imaging may be helpful. Surgical resection of the tumor is the treatment of choice. Arthroscopic resection is superior to an open procedure & has distinct advantages.
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Fig. 3 Arthroscopic picture after complete resection of tumor.
At 6 months follow up there was complete resolution of
his symptoms with no sign or symptoms of recurrence of
the tumor.
DISCUSSION
Fig. 1 MRI scan showing intraarticular lesion in anterior
compartment.
containing lipid, and proliferation of multinucleated giant
cells and fibroblasts (Fig. 5), consistent with the diagnosis
of pigmented villonodular synovitis.
Fig. 2 Arthroscopic picture showing a well defined soft tissue
lesion.
Villous, inflammatory nodular neoplasms of the synovial
membrane were first described in the 19th century. Because
of their uncertain pathogenetic classification, these lesions
of the synovial membrane were given various different
names, such as xanthomatous giant cell tumor, histiocytic
giant cell tumor, xanthoma, benign synovialoma, haemorrhagic villous arthritis and localized pigmented villonodular
synovitis (PVNS). The term PVNS was introduced by Jaffe
et al1 in 1941 and subsequently gained general acceptance.
Pigmented villonodular synovitis (PVNS) is a synovial
Fig. 4 Histopathological picture showing haemosiderin laden
macrophages.
4. Arthroscopic resection of localized pigmented villonodular synovitis of the knee
Fig. 5 Foam cells containing lipid, and proliferation of
multinucleated giant cells and fibroblasts.
proliferation disorder that remains a diagnostic difficulty
because of its nonspecific presentation and subtle radiographic findings. Clues gathered through the history, physical examination, and radiographic studies could aid in
reaching the diagnosis. Despite magnetic resonance
imaging (MRI) sensitivity in revealing findings consistent
with PVNS, these findings are neither constant nor specific
for PVNS.2 At present, generalized pigmented villonodular
synovitis (GVNS) is differentiated from localized pigmented villonodular synovitis (LVS). LVS is further subdivided into an articular (ALNS) form and an extra-articular
(ELNS) form.3 Myers and Masi4 describe 166 cases, with
ELNS occurring in 70.5%, GVNS in 23.5%, and ALNS
in only 6%. ALNS is thus rare, with an estimated prevalence of 1.8 per 1 million population. Most patients with
PVNS are in their thirties.4,5 There is no specific sex predilection.5,6 The involvement of several joints has only been
described for GVNS.6,7
The etiology of pigmented villonodular synovitis remains
controversial.3,8 The most widely held theory is that the
disease is an inflammatory reaction of the synovium.1,3
However, some evidence exists that it is a benign neoplastic
process.9 It is nearly always monoarticular. The knee is the
most common joint involved, representing 80% of cases, followed by the hip (15%) and the ankle (5%).
The onset of symptoms is typically insidious. The
average duration of symptoms before diagnosis has been reported to be between 10 and 26 months (range 2e72
months). The lesion is manifested by nonspecific clinical
symptoms such as locking, giving away, localized tenderness, pain, diminished range of motion, mass effect,
swelling, stiffness, snapping, or instability.10 Localized
PVNS of the knee can present with an insidious onset or
in association with trauma. It usually affects adults in their
third to fourth decade. The patient may present with pain,
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commonly anterior, as well as mechanical symptoms such
as locking, catching, popping, instability, or swelling. The
pain is seldom severe.9 Physical findings associated with
localized PVNS of the knee may include pain exacerbated
by forced flexion or flexion under mechanical loading.
Clinical findings consistent with mechanical internal
derangement can mimic meniscal pathology or foreign
body. Rarely, a palpable mobile mass is noted on exam.5
Radiographs usually are normal except in 15% of cases
which show radioluscent lesion, osteopenia or degenerative
changes. Aspirated synovial fluid is typically xanthochromic
or serosanguinous. MR images demonstrate various appearances ranging from low signal through isointense to hyperintense signals on spin-echo images, reflecting the presence of
blood and its degradation products. Hemosiderin appears as
low signal on T1- and T2-weighted images. Although
magnetic resonance imaging is reasonably sensitive to
demonstrating findings consistent with localized PVNS, it
is not specific. Localized PVNS on MRI can easily be
mistaken for loose body, meniscal pathology, hematoma,
synovial hemangioma, malignant neoplasm, or fibroxanthoma.5 Typical findings include a well-circumscribed lesion
with focal hypointense areas on T1- and T2- weighted
images, reflecting the amount of hemosiderin present.9
Several authors have described the arthroscopic appearance of localized PVNS.2,5,7e9 Localized PVNS most
commonly appears as a pedunculated, mildly pigmented,
nodular mass that is brown or yellow in color.11 Locations
of origin that have been reported included the meniscus, the
meniscosynovial junction, the fat pad, and the medial and
lateral gutters.1,5,8,11 Howke et al reported the most frequent
location of origin to be the medial and anterior compartments. While surgical treatment of the diffuse type is associated with a high recurrence rate, many authors have
reported good results with arthroscopic local resection of
the localized type.5,7e9,11 Arthroscopic resection of localized PVNS, first described by Flandry in 1986,2 is a wellrecognized, successful procedure. Unlike the results for
the diffuse type of PVNS, recurrence of the localized type
after arthroscopic local resection is rare.8 Also, arthroscopy
has been noted to be superior to arthrotomy for exploration
of the posterior compartment of the knee, an area where
localized PVNS has been noted to originate. Arthroscopic
resection is better, because whole swelling can be resected
adequately under arthroscopic vision, without damaging
other intraarticular structures. Significant morbidity after
arthroscopic resection is rare. Hence, we recommend
arthroscopic resection of localized PVNS lesions.
Jaffe described the histologic findings of PVNS as
fibrous or hyalinized stroma, pigment deposition, histiocytic infiltrate, and giant cells within a synovial capsule.1
Proliferating synovial cells are often noted in ill-defined
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nodules accompanied by a random distribution of giant
cells.5 Macrophage activity is often noted with phagocytosis of hemosiderin and lipids.
An awareness high index of suspicion is also required
to diagnose treat these benign lesions.
CONFLICTS OF INTEREST
All authors have none to declare.
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3. Granowitz SP, D’Antonio J, Mankin HL. The pathogenesis
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4. Myers BW, Masi AT. Pigmented villonodular synovitis and
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