L. P. Müller (쾷) · J. Degreif · P. M. Rommens Klinik für Unfallchirurgie, Johannes-Gutenberg-Universität Mainz, Langenbeckstrasse 1, D-55101 Mainz, Germany Tel.: +49-6131-172 845 Fax: +49-6131-176 687 M. Bitzer Institut für Pathologie, Johannes-Gutenberg-Universität Mainz, Langenbeckstrasse 1, D-55101 Mainz, Germany
Pigmented villonodular synovitis of the shoulder: review and case report
Abstract Pigmented villonodular synovitis (PVNS) as reviewed in detail elsewhere most frequently involves the knee and finger synovial structures; shoulder involvement is rare: A search through the English literature yielded 18 publications describing 25 cases of PVNS affecting the shoulder joint. Analyzing these reports we found the clinical and radiological findings generally to be nonspecific, often mimicking a malignancy, as in the case presented here of a 16-year-old boy with painful swelling in the area of the left proximal humerus. Magnetic resonance imaging showed a suspected malignant soft tissue mass involving the shoulder capsule and measuring 7.5 × 6 × 4 cm. Preoperatively the patient could recall no trauma; however, postoperatively he did report a
Introduction Pigmented villonodular synovitis (PVNS) is a benign tissue proliferation which presents as a borderline case between a reactive and a neoplastic process and emanates from the tendosynovial layers, the joint capsule, or the synovial bursa. Two forms of PVNS can be differentiated macroscopically: the diffuse form, which involves the entire synovia of a joint, and the localized form with isolated tissue masses in the synovia. The nodular proliferations are partially encapsulated and show a poorly defined border with the surrounding soft tissue. Histologically, hyperplastic synovial villi with many foam cells and hemosiderin-storing macrophages are seen, as well as multinuclear giant cells.
distorsion trauma of the affected shoulder following a bicycle accident. Intraoperatively, two tumors were found infiltrating the axillary vessels and nerve and tendon structures originating in the capsule of the shoulder joint. Rapid sections of the tissue revealed no signs of malignancy; further pathohistological examination revealed localized PVNS. Preoperatively, the shoulder joint was not suspected as the primary site of origin of the tumor because the patient had no complaints or functional deficits of the shoulder. The clinical presentation of such a PVNS lesion over the proximal humerus is unusual and to date has only twice been described in the literature. Key words Pigmented villonodular synovitis · Shoulder · Trauma
Primarily, PVNS appears in the synovial structures of the fingers and the knee joint capsule; it occasionally involves the hip and ankle joint, and very rarely involves the shoulder. Polyarticular PVNS appears in less than 1% of all cases . Neither the incidence nor the prevalence of the disease is clear, but approximately 1% of joint diseases that occur are cases of PVNS . The rate of incidence is approximately 2 cases per 1 million persons . The occurrence of relapse-prone PVNS is nonspecific with regard to sex and age; however, persons in their 30s and 40s are predominantly affected . Typically in cases of PVNS (including the case reported here) the history as well as the clinical and imaging results are nonspecific and can mimic a malignancy, as documented by the present literature review which gives an overview of the 25 cases of PVNS affecting the shoulder joint published so far.
PVNS in the shoulder is extremely rare: in the 166 cases studied by Mohr , none described any involvement of the shoulder, while in the study by Schwartz et al.  only 2 of 99 cases involved the shoulder. As to the clinical signs, most of the patients present with progressive painful swelling and limitation of motion of the affected shoulder joint. Joint stiffness is common in cases of long duration. The disease is characteristically monarticular and usually slowly progressive; 2–3 years often elapse before the patient seeks medical advice. The radiological signs are bone cysts seen at some distance from the articular surface of the affected joint. They vary in appearance, being usually well-defined and non-calcified; there is no narrowing of the joint space apart from in the final stages of the disease, when necrosis and arthritic changes can be seen. Therapeutic approaches include total and local synovectomy, total shoulder arthroplasty, and radiotherapy.
Materials and methods To determine the incidence of shoulder involvement in PVNS, a review of the literature was carried out. The isolated 25 reports connecting the PVNS to the shoulder joint were analyzed with regard to clinical and radiological findings, treatment, and outcome (Table 1), so far as these data were available in the original 18 publications. In the case report of a 16-year-old boy who presented with painful swelling in the proximal area of the left proximal humerus, we describe preoperative imaging results including magnetic resonance imaging, intraoperative findings and procedures, and histopathological and electron microscopic results.
Results Case report History and clinical findings A 16-year-old athletic male presented with no significant medical problems and an unremarkable family history. Preoperatively, the patient could remember no trauma, despite careful questioning. Postoperatively, the patient did report a fall from his mountain bike approximately 1 year before, where he injured his left shoulder. Afterwards, he suffered pain during movement as well as swelling and a hematoma in the ventrocaudal area of the left shoulder. The patient went to his primary physician the day after the accident. Voltaren (diclofenac) salve and tablets were prescribed and the patient reported improvement after 2– 3 days. Four months later, the patient noted for the first time an area of swelling over the proximoventral region of the left upper arm, which was increasing in size and was painful to pressure. After magnetic resonance imaging of this area, performed on an outpatient basis, a malignant tumor of the soft tissue was suspected and the patient admitted for operative therapy. Inspection revealed a mass approximately
7 × 6 × 4 cm in size in the proximoventral area of the left upper arm between the two heads of the biceps brachii muscle (Fig. 1). The skin over this area showed striae distensae with diffuse subcutaneous bleeding areas. On palpation, the area was painful to pressure and was immobile against the surrounding soft tissue. There were no functional or neurovascular deficits in the left upper extremity. Imaging procedures Radiologically, the lateral cortex in the area of the proximal humerus was irregularly structured. As a result, a malignant soft tissue tumor with bone involvement was suspected. Magnetic resonance imaging showed an ovalshaped, nodular, and smoothly contoured mass in the proximal area of the left biceps brachii muscle, which could be traced proximally to the intertubercular fossa of the humerus (Fig. 2). A portion of the tumor projected medially underneath the coracoid process along the frontal plane of the subscapular muscle until it approached the left wall of the thorax. In light of the magnetic resonance imaging, a malignant soft tissue tumor was suspected with lateral displacement of the long biceps tendon and medial displacement of the long head of the biceps brachii muscle. Intraoperative findings A partially encapsulated tumor was found, measuring 7.5 cm. There was infiltration into the proximal portions of the caput breve and caput longum of the biceps as well as into the plexus brachialis, the axillary artery and vein, and the proximal humerus. A second tumor measuring 5 cm was found under the coracoid processus. Both tumors were connected to the shoulder joint capsule. As the rapid section showed no signs of malignancy, local extirpation was carried out. Histological findings Macroscopic inspection showed a 7.5-cm, partially encapsulated tumor with a soft, golden-brown surface and accentuated central villous structures. Histologically, a tumor-like lesion was found with enlarged synovial villi that exhibited a hyperplastic epithelial cell layer. Underneath, there were numerous densely distributed monomorphic, mononuclear, fibroblastic as well as myofibroblastic spindle cells. There were also diffuse elongated areas with siderophages, numerous foam cells, and occasional multinuclear giant cells. Atypical cells and nuclei were not found; the rate of mitosis was not increased (Fig. 3).
2a Fig. 1 Preoperative clinical findings in our 16-year-old male patient: a tumor measuring approximately 7 × 6 × 4 centrocaudal to the left shoulder. Striae distensae in the overlying skin Fig. 2 a Sagittal magnetic resonance image of the left shoulder region. In the proximal area of the left biceps brachii muscle an ovalshaped, nodular and smoothly contoured mass is visible, which can be traced proximally to the intertubercular fossa of the humerus head and is in contact with the shoulder joint capsule. b Transverse magnetic resonance image at the level of the proximal part of the shaft of the humerus, showing lateral displacement of the long biceps tendon and medial displacement of the biceps brachii muscle by the tumor Fig. 3 Histologically, a tumor-like lesion is shown with enlarged synovial villi which exhibit a hyperplastic epithelial cell layer. Numerous densely distributed monomorphic, mononuclear, and fibroblastic spindle cells are seen as well as diffuse elongated areas with siderophages and many foam cells. There are also occasional multinuclear giant cells. Atypical cells and nuclei were not found. The rate of mitosis was not increased
Electron microscopic findings There was evidence of numerous areas of phagocytic cell membranes with many lysosomes as well as phagocytic material (Fig. 4). The nucleus had a heterochromatin seam, and next to it were fibroblasts and myofibroblasts. Literature review (Table 1) Incidence and location of PVNS Shoulder involvement in PVNS has been reported in only 25 cases published in 18 studies; in only one case was the lesion reported as completely extra-articular, originating from an abnormal bursal lesion anterior and inferior to the supraspinatus insertion on the greater tuberosity . In 4 cases a history of trauma was established [4, 10, 11, 36]. Patient sex was recorded in the published articles in 18 cases (8 women, 10 men), the mean age at the time of
Fig. 4 Electron microscopy showed phagocytic cell membranes in numerous areas with many lysosomes as well as phagocytic material. The nucleus had a weak heterochromatin seam, and next to it were fibroblasts and myofibroblasts
diagnosis being 60.7 years for the female patients (range: 18–84 years) and 43.5 years for the male patients (range: 5–64 years). The mean duration of symptoms prior to the diagnosis of PVNS was 33.9 months (range: 1 week to 9.5 years). The occurrence of PVNS in the shoulder is extremely rare. In the 166 cases studied by Mohr , involvement of the shoulder was described in none, while in the study by Schwartz et al.  only 2 of 99 cases involved the shoulder (Table 2). Clinical signs of PVNS Most patients presented with progressive painful swelling and limitation of motion of the affected shoulder joint, though Byers et al.  describe a case in which swelling and loss of motion occurred without any pain at all. The disease is characteristically monarticular and usually slowly progressive; 2–3 years often elapse before the patient seeks medical advice. Although pain is not usually severe, it can occasionally be a definite symptom; swelling is nearly always present. Joint stiffness is common in cases of long duration due to synovial thickening. The joint is usually not tender . Radiological signs of PVNS Bone lesions in PVNS are not rare [5, 7, 26, 31]: the classical X-ray findings, apart from soft tissue swelling when a
superficial joint is involved, are the bone cysts seen at some distance from the articular surface of the affected joint. They vary in appearance, being usually well-defined and uncalcified; there is no narrowing of the joint space except in the final stages of the disease, when necrosis and arthritic changes can be seen. Nearly all authors who draw attention to radiological changes in PVNS of the shoulder in the adjacent bone saw demineralization and degenerative processes on the plain X-ray images, such as cortical erosions, bony cysts in the humeral head, glenoid, or greater tuberosity, generalized demineralization of the humeral head, subcortical sclerosis, and osteoarthritis. The pathogenesis of these characteristic bone cysts is not clear. It has been postulated that the exuberant villonodular tissue and the joint effusion cause high intra-articular pressure. This in turn results in small areas of osteoporosis near the joint, where the bone cysts develop. The cysts thus formed are finally invaded by the hypertrophic synovium of the joint through fractures in the cyst walls . The high intra-articular pressure found by other authors as well [26, 31] may explain why bone cysts are rare in the knee joint, which is more usually affected by the disease: the articular cavity of the knee is large and can be expanded, unlike joints more rarely involved by the disease, such as the hip or the shoulder, in which bone changes are a rather common finding. According to Pantazopoulos  the cysts are created by the extension of villonodular tissue into the bone through the chondro-osseous area at the articular margin. Scott  has found that the bone is invaded by the hypertrophic synovium through the vascular foramina along with the epiphyseal vessels. The villonodular tissue thus invading the bone is further expanded within the bone cysts by pressure atrophy. Treatment of PVNS Approaches to treatment have included total and local synovectomy, total shoulder arthroplasty, and radiotherapy. There is not much data available concerning recurrence rates after the different procedures, although radiotherapy was unsuccessful in both cases mentioned, total synovectomy plus total shoulder replacement arthroplasty being indicated when massive arthrotic changes are seen (for further treatment regimes for PVNS and data concerning recurrence rates see below in the Discussion).
Discussion The clinical symptoms of PVNS are nonspecific (Table 1); there is usually monarticular restriction of movement accompanied by intermittent pain and recurrent swelling of the affected joint [14, 28]. The tumors may adhere to the synovial membrane and project into the interior of the joint . If incarceration occurs, joint blockade may become apparent, so that the first diagnosis for a knee joint af-
Table 1 Results of the literature review of PVNS with shoulder involvement: clinical picture (± = with/without, PA pain history, SW swelling, LOM lost of motion), radiological features (PR plain X-ray, CT computed tomography, MR magnetic resonance, HH
humerus head), treatment approaches, and recurrence data when available (PS partial synovectomy, R recurrence, TSP total shoulder replacement)
+PA (12 months, gradually increasing) +SW, +LOM
PR: radiolucency HH, bone cyst 1 × 0.6 cm surrounded by dense ring bone
+PA (1 week) +SW, +LOM
PR: subcortical sclerosis, generalized demineralization HH, irregular subchondral articular bone
1. Local excision, post-op. intermittent pain attacks (diffuse PVNS) 2. Radiotherapy Patient refused exploration of the joint: 1.750 r X-ray therapy over 15 days; 6 weeks alter R
+PA (9.5 years, treated with steroids for last 4 years)
+PA, +LOM (9 months)
Contrast arthrogram: filling of subacromial and subdeltoid bursa; PR: cystic changes greater tuberosity, entire shoulder PR: cystic changes HH and glenoid, distension of the joint capsule by a lobulated soft tissue mass
Pantazopoulos et al. 
+PA (progressive) en- PR: bony cysts HH larged subdeltoid bursa
PS, excision of subdeltoid bursa, curettage of bony cysts, no R 3 years post-op.
+PA (3 years), +SW +PA (7.5 years), +SW
No data No data
PS, no R TPS, total synovectomy
Smith & Pugh 
PR: cortical erosions HH
Byers et al. 
–PA, joint effusion
No R, (diffuse)
Seiler et al. 
+PA (several months), +SW (4–5 years), skin temperature ↑
PR: spindle-shaped homogeneous and sharply outlined soft tissue mass extending from the region of the coracoid process to the deltoid tubercle 6 months progressive PR: polycyclic pattern of destruction of PA +SW (+ 4 cm mass the entire HH sparing subarticular cortex over bicipital groove)
Intra-op: 3 × 7 × 11 cm mass densly adherent to the surrounding tissues soft tissue mass PS (diffuse) Intra-op.: large mass enveloping the long head of the biceps, curettage HH, PS (diffuse)
2 × extensive synovectomy + Neer TPR (diffuse) 1 × extensive S (diffuse + necrosis HH) 1 × PS (nodular), all 4 cases no R 2 years post-op.
Johansson et al.  4 cases, average 35 years
Table 2 Distribution of lesions in PVNS in five studies (diff. diffuse form of PVNS, local. localized form of PVNS)
Hand Wrist Elbow Shoulder Spine Hip Knee Ankle Foot
– 2 – 1 – 2 24 5 –
26 – – – – – 13 – 7
1 – – 1 – 7 24 1 –
– – – – – – 4 – –
– – 2 2 – 20 75 – –
2 – – – – 5 35 4 –
60 – 1 – 1 7 46 3 2
– – – 3 – 4 24 2 –
– 1 – 1 – – 7 2 –
fected by PVNS is most often – in approximately 80% of all cases  – “meniscopathy” . In the case described here, there were absolutely no complaints of pain in the joint and no restriction of movement. What was noticed was a mass on the proximal upper arm (Fig. 1), which because of its distance from the shoulder was not at first believed to be the termination of a lesion of the joint. The results of imaging PVNS are also nonspecific  and seldom contribute to reaching a definitive diagnosis. The magnetic resonance images (Fig. 2) suggest a malignant process because of the infiltration of the lesion into the surrounding soft tissue, but a benign process still cannot be ruled out. Radiologically, bone erosion and cysts can be identified. On the basis of experiments on the head of the femur,
Scott  was of the opinion that the tissue of diffuse PVNS enters the bone over the nutrient foramina and here lead to disintegration of bone. In this context, Chung and Janes  introduced their hypothesis that infiltration of PVNS into the bones occurs mainly in joints without large articular cavities, because the expanding tumor mass leads quickly to increased pressure with compression of the vessels and consequently reduces blood supply. This explains the markedly higher incidence of bony lesions in case of PVNS in the hip joint (16 of 20 cases ) than in other joints. The cyst-related brightening in the head of the humerus described in the present case were also described in most cases of PVNS described in the shoulder (Table 1). Being aware of these possible presence of these bone changes in PVNS is very helpful in distinguishing this
condition from other more common joint diseases with similar bone changes, such as osteoarthritis, monarticular rheumatoid arthritis, and avascular necrosis. This is even more important since the bone changes occurring in PVNS can be mistaken for a neoplastic bone or joint lesion such as malignant synovioma [20, 26]. Preoperative imaging procedures suggest a malignant process. Histologically, a malignant process cannot be safely ruled out on the basis of the rapid section. A radical surgical procedure in the case of PVNS is not, however, indicated when a benign, nonmetastatic tissue mass is involved, even if it is locally aggressive in growth . At the same time, a malignant process such as a synovial sarcoma cannot be ruled out on the basis of preoperative radiological diagnostic procedures . Most authors recommend local excision in cases of the localized form of PVNS and total synovecomy in cases of the diffuse form of PVNS. Total synovectomy is a difficult procedure and is in most cases impossible to carry out completely. Johansson et al.  reported a recurrence rate of 33%, while Byers et al.  found 50% recurrence after total synovectomy in diffuse PVNS. In addition, this procedure is associated with a high rate of complications, especially postoperative movement restriction. As a result, Bentley and McAuliffe  favor local extirpation in cases of diffuse PVNS as well as the localized form of PVNS (when possible, arthroscopically) even though the recurrence rate is relatively high. Byers et al.  reported a relapse rate of 50% in PVNS of the knee joint. Johansson et al.  as well as Rao and Vigorita , by contrast, reported a rate of only 33% despite “total synovectomy.” Rao and Vigorita also determined an average period of 17.5 months until relapse occurred. Flandry et al.  found, to the contrary, that only 8% of patients relapsed (2 of 25 cases of diffuse PVNS of the knee joint) after radical synovectomy via a combined ventral and dorsal approach. In his follow-up study of histological preparations, Mohr  identified relapse in 23% (11 of 46) of cases of diffuse PVNS and only 5% (3 of 60) of cases of localized PVNS of the hand. In a retrospective analysis of 99 patients with PVNS of the knee, shoulder, and elbow, Schwartz et al.  found a relapse rate of 35% over 25 years. After 1 year the cumulative risk of relapse was 7.1%, after 2 years it was 15%, after 10 years 27%, after 15 years 31%, and after 25 years 35%. The relapse rate in this study did not show a dependence on the histological type of PVNS (nodular or diffuse). There is no agreement in the literature as to whether a pathogenetic relationship exists between PVNS and preceding trauma. Intra-articular hemorrhage can be ruled out as a triggering factor with a high degree of certainty  because similar lesions do not occur in patients with recurring hemorrhages in the joints (e.g., hemophiliacs) [1, 13]. In his study, Mohr  found that of 166 cases of PVNS (46 diffuse and 120 localized), a mere 14 had suffered previous mechanical damage to the affected joint.
Two were cases of meniscopathy, and 11 had had surgery earlier. Flandry et al.  had report, of trauma in 12 of 26 patients with diffuse PVNS and suggested this as a possible causative factor. In a survey of literature, Meyer et al.  found a statistically significant relationship between PVNS and chronic recurring trauma. Gallacchi  described a case of localized PVNS in a patient after recurrent distortion of the ankle joint. Chassaignac  described a lesion of nodular form arising in relation to the flexor tendon sheaths of the middle fingers in 1852, and Jaffe et al.  introduced the term “pigmented villonodular synovitis” nearly 100 years later in 1941, yet the etiological agent is still unknown and the true nature of the disease process is still in dispute: The paper by Jaffe et al. , based on clinical and pathological experience of 20 cases involving joints, tendon sheaths, and bursae, is still the definitive account to the condition. They observed that the nodular and diffuse lesions were histologically similar, and suggested that they belonged to the same disease. The benign course, together with the histological appearance of the lesions, led them to conclude that the condition was not a tumor, but an inflammatory response to an unknown agent. In 1954 Young and Hudacek  produced changes which they regarded as similar to those of PVNS by repeated injection of blood into the knees of dogs. It has been suggested, however, that these changes are not really comparable with those of PVNS, but more closely resemble those seen in hemophilia . Geschickter and Copeland  suggested that the lesion originates from osteoclasts in the sesamoid bones, but the anatomical sites of the lesions make this untenable. A disorder of lipid metabolism has been postulated by several authors, including De Santo and Wilson  and Galloway et al. , who found raised blood cholesterol levels in some of their patients, but an association with a disorder in cholesterol metabolism could not be proven . It is also frequently surmised that a genetic factor plays a role . Chromosomal deviations can also be determined in cytogenetic studies . In normal synovia, fibrohistiocytic cell elements are found, but in PVNS these proliferated cell elements are of polyclonal origin. As a result, some authors suspect reactive tissue growth as a pathogenesis [24, 30]. Other authors discuss the possibility of an inflammatory origin of PVNS, no causative pathogen has been successfully isolated [1, 24]. Because patients with PVNS present with a nonspecific clinical set of symptoms and imaging findings, a malignant process may be suspected. The suspicion is only strengthened when intraoperatively a tumor is found with infiltration of soft tissue and bone. Malignancy cannot be ruled out with certainty on the basis of the histological results of the rapid resection. A radical surgical procedure is not, however, indicated in PVNS.
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