Osteoclast-rich, proximal-type epithelioid sarcoma: clinicopathologic features of 3 unusual cases expanding the histomorphological spectrum.

Epithelioid sarcoma (ES) displays a wide clinicopathologic spectrum. On histopathology, osteoclast-like giant cells have been rarely described in these tumors. A 45-year-old gentleman presented with a perineal swelling of 6-month duration. Radiologic imaging disclosed a large, highly vascular tumor mass in his perineal region that was diagnosed elsewhere as pigmented villonodular synovitis. A 58-year-old lady presented with a recurrent tumor in her right inguinolabial region for which she underwent multiple tumor resections in the past. A 33-year-old lady presented with a right inguinal swelling of 1-month duration that was diagnosed elsewhere as a non-Hodgkin lymphoma on fine needle aspiration cytology. Histopathologic examination of tumors in all the 3 cases revealed epithelioid to "rhabdoid-like" cells arranged in a diffuse pattern interspersed with many osteoclast-like giant cells. The first tumor also revealed focal pseudoangiosarcomatous areas and heterotopic bone formation. By immunohistochemistry, tumor cells in all 3 cases were positive for AE1/AE3, epithelial membrane antigen, and CD34 and were completely negative for INI1/SMARCB1. CD68 immunostaining in 2 tumors highlighted osteoclast-like giant cells. Osteoclast-rich, proximal-type ES are unusual tumors, indicative of an expanding spectrum of ESs. Awareness of this histopathologic pattern and diagnostic confirmation with necessary immunohistochemical stains is crucial to avoid misinterpretation, as these tumors are clinically aggressive and are treated with wide local excision and optional adjuvant radiation therapy.

CSF1R inhibition with emactuzumab in locally advanced diffuse-type tenosynovial giant cell tumours of the soft tissue: a dose-escalation and dose-expansion phase 1 study.

BACKGROUND: Diffuse-type tenosynovial giant cell tumour (dt-GCT) of the soft tissue (alternatively known as pigmented villonodular synovitis), an orphan disease with unmet medical need, is characterised by an overexpression of colony-stimulating factor 1 (CSF1), and is usually caused by a chromosomal translocation involving CSF1. CSF1 receptor (CSF1R) activation leads to the recruitment of CSF1R-expressing cells of the mononuclear phagocyte lineage that constitute the tumor mass in dt-GCT. Emactuzumab (RG7155) is a novel monoclonal antibody that inhibits CSF1R activation. We have assessed the safety, tolerability and activity of emactuzumab in patients with Dt-GCT of the soft tissue. METHODS: In this phase 1, first-in-human dose-escalation and dose-expansion study, eligible patients were aged 18 years or older with dt-GCT of the soft tissue with locally advanced disease or resectable tumours requiring extensive surgery, an Eastern Cooperative Oncology Group performance status of 1 or less, measurable disease according to Response Evaluation Criteria In Solid Tumors version 1.1, and adequate end-organ function. Patients with GCT of the bone were not eligible. Patients received intravenous emactuzumab at 900 mg, 1350 mg, or 2000 mg every 2 weeks in the dose-escalation phase and at the optimal biological dose in a dose-expansion phase. The primary objective was to evaluate the safety and tolerability of emactuzumab, and to determine the maximum tolerated dose or optimal biological dose. All treated patients were included in the analyses. Expansion cohorts are currently ongoing. This study is registered with ClinicalTrials.gov, number NCT01494688. FINDINGS: Between July 26, 2012, and Oct 21, 2013, 12 patients were enrolled in the dose-escalation phase. No dose-limiting toxicities were noted in the dose-escalation cohort; on the basis of pharmacokinetic, pharmacodynamic, and safety information, we chose a dose of 1000 mg every 2 week for the dose-expansion cohort, into which 17 patients were enrolled. Owing to different cutoff dates for safety and efficacy readouts, the safety population comprised 25 patients. Common adverse events after emactuzumab treatment were facial oedema (16 [64%] of 25 patients), asthenia (14 [56%]), and pruritus (14 [56%]). Five serious adverse events (periorbital oedema, lupus erythematosus [occurring twice], erythema, and dermohypodermitis all experienced by one [4%] patient each) were reported in five patients. Three of the five serious adverse events-periorbital oedema (one [4%]), lupus erythematosus (one [4%]), and dermohypodermitis (one [4%])-were assessed as grade 3. Two other grade 3 events were reported: mucositis (one [4%]) and fatigue (one [4%]). 24 (86%) of 28 patients achieved an objective response; two (7%) patients achieved a complete response. INTERPRETATION: Further study of dt-GCT is warranted and different possibilities, such as an international collaboration with cooperative groups to assure appropriate recruitment in this rare disease, are currently being assessed. FUNDING: F Hoffmann-La Roche.

Osteoclast formation and function in pigmented villonodular synovitis.

Pigmented villonodular synovitis (PVNS) is a synovial tumour-like lesion that frequently causes osteolysis. PVNS contains numerous macrophages and osteoclast-like giant cells. In this study, we have analysed the cytochemical and functional characteristics of mononuclear and multinucleated cells in PVNS and determined the cellular and humoral mechanisms underlying giant cell formation and resorption in PVNS. Giant cells and CD14(+) and CD14(-) mononuclear cell populations were isolated from PVNS synovial tissue and cultured alone or in the presence and absence of the osteoclastogenic factors, RANKL and M-CSF. Osteoclast formation and activity was assessed by expression of TRAP and evidence of lacunar resorption. Giant cells in PVNS expressed an osteoclast-phenotype (CD51(+) , TRAP(+) , CD14(-) , HLA-DR(-) ) and were formed only in cultures of mononuclear cells that expressed the macrophage marker CD14. Osteoclast formation required RANKL and occurred in both the presence and absence of exogenous M-CSF. CD14(-) cells in PVNS expressed RANKL. Lacunar resorption by PVNS-derived giant cells was abolished by the addition of the bisphosphonate, zoledronate. Our findings indicate that osteoclasts form by a RANKL-dependent mechanism from CD14(+) mononuclear phagocytes in PVNS. Osteoclast formation occurred even in the absence of exogenous M-CSF, a finding which is in keeping with over-expression of M-CSF playing a pathogenic role in this condition. Anti-osteoclast resorptive treatment may be useful to control osteolysis in PVNS.

Synoviocytes from pigmented villonodular synovitis are less sensitive to cadmium-induced cell death than synoviocytes from rheumatoid arthritis.

Pigmented villonodular synovitis (PVNS) is a rare inflammatory articular disease sharing common characteristics with rheumatoid arthritis (RA), notably hyperplasia of the synovium due to a hyperproliferation of synoviocytes, and with cancer owing to mutations of the CSF1/M-CCSF gene. Targeting synovium hyperplasia by the local delivery of Cadmium (Cd) has been already tested in vitro and in vivo models of RA and could be applied to PVNS. PVNS and RA synoviocytes were exposed to low doses of Cd. After different culture time points, a qualitative analysis was done by microscopy and quantitative measurements of apoptosis, cell viability and IL-6 production were carried. IL-6 production by PVNS synovial tissue was also quantified after Cd treatment with or without the presence of pro-inflammatory cytokines (IL-17 + TNF). Addition of Cd induced cell death in both PVNS (1 ppm) and RA (0.1 ppm) synoviocytes, which increased with time and Cd concentrations. Cd increased the percentage of apoptotic cells and decreased cell viability and IL-6 production. In all these experiments, PVNS synoviocytes were tenfold less sensitive to Cd than RA synoviocytes. Cd decreased IL-6 production by PVNS synovial tissue and its effect was enhanced with pro-inflammatory cytokines. In summary, PVNS synoviocytes show resistance to Cd-induced cell death and decreased inflammation. Intra-articular use of Cd could represent a potential therapeutic tool in PVNS.

Synovial colony-stimulating factor-1 mRNA expression in diffuse pigmented villonodular synovitis.

OBJECTIVES: To delineate the molecular mechanisms underlying the process of the diffuse-type giant cell tumours, also called pigmented villonodular synovitis, a rare, aggressive condition of the synovium, the knee synovial tissue expression of colony-stimulating factor-1 gene, as detected by real-time polymerase chain reaction, was compared between patients affected with pigmented villonodular knee synovitis and knee meniscal tears, or persistent gonoarthitis. METHODS: Multiple synovial biopsies of the knee were performed by arthroscopy in five consecutive patients affected by diffuse pigmented villonodular knee synovitis and in 12 patients affected by knee meniscal tears (n. 6) or persistent active gonarthritis (n. 6), recruited from the patients attending the Rheumatology Day Surgery Outpatient Clinic of the University of Padova Hospital. The ethics committee approved the study protocol and the participants signed consent statements after being informed about the content of the study. The diagnosis was made on the basis of a histological examination. The colony-stimulating factor-1 gene expression was assessed by reverse transcription followed by real-time polymerase chain reaction. RESULTS: The detection by RT-PCR of synovial colony-stimulating factor-1 mRNA showed a wide spectrum of expression in the three groups of distinct knee joint disease affected patients, with significantly higher level of colony-stimulating factor-1 mRNA expression in synovial tissue of pigmented villonodular synovitis, in comparison to that of knee meniscal injuries and persistent gonoarthritis patients. CONCLUSIONS: Our findings point out to an important role of colony-stimulating factor-1 in pigmented villonodular knee synovitis disease process and support the idea that colony-stimulating factor-1/colony-stimulating factor-1 receptor interaction may represent a potential therapeutic target of this disease.

cIAP2 expression and clinical significance in pigmented villonodular synovitis.

Pigmented villonodular synovitis (PVNS) is a rare hyperplasia disease of the synovium with a predilection for the knee in either a localized (LPVNS) or a diffuse form (DPVNS). But the exact cause is not clear. The aim of this study was to explore the relationship between the expression of cellular inhibitor of apoptosis 2 (cIAP2) and proliferation, apoptosis, invasive growth and postoperative recurrence in PVNS. Clinical significance of cIAP2 expression in synovium from 63 patients' knee joints with PVNS (40 DPVNS; 23 LPVNS) were investigated with 20 normal subjects acting as controls. The cIAP2 gene was screened by Human Cancer Pathway Finder PCR Array and real-time polymerase chain reaction (RT-PCR). We also used immunohistochemistry to detect cIAP2 and proliferating cell nuclear antigen (PCNA) protein expression and analyzed their relationship with PVNS type, invasive growth, and postoperative recurrence. The expression of cIAP2, PCNA, caspase-8, caspase-9 and caspase-3 protein was tested in Western blot. Screening results of Human Cancer Pathway Finder PCR array and RT-PCR showed significantly more cIAP2 mRNA in DPVNS synovium than in normal or LPVNS synovium (P < 0.05). Immunohistochemistry and western blot showed that the cIAP2 protein expression level in DPVNS was significantly higher than in LPVNS tissue (P < 0.01). As cIAP2 expression increased, the expression of PCNA increased (P < 0.05) and expression of cleaved caspase-3, -8, -9 decreased (P < 0.01). cIAP2 and PCNA overexpression were found to be related to ligament and bone erosion in PVNS and to disease recurrence (P < 0.05). This study suggested that cIAP2 overexpression plays an important role in the anti-apoptotic, proliferative and invasive growth of PVNS, which may account for the recurrence and poor prognosis of DPVNS.

Translocation and expression of CSF1 in pigmented villonodular synovitis, tenosynovial giant cell tumor, rheumatoid arthritis and other reactive synovitides.

We recently demonstrated that CSF1, the ligand of the tyrosine kinase receptor, CSF1R, can be translocated in pigmented villonodular synovitis (PVNS) and tenosynovial giant cell tumor (TGCT). In this study, we evaluated the staining characteristics of PVNS/TGCT and reactive synovitides for CSF1 and CSF1R by in situ hybridization and immunohistochemistry on tissue microarrays and correlated these findings with the recently described translocation. We collected specimens of TGCT/PVNS from 60 patients and of rheumatoid arthritis and other reactive synovitides from 74 patients. We identify 2 groups of PVNS and TGCT cases by the presence of CSF1 translocation and CSF1 expression. The first group (35 of 57 cases; 61%) had both the CSF1 translocation and high expression of CSF1 RNA, confirming our previous findings. Interestingly, a second group (22 of 57 cases; 39%) was identified that showed high expression of CSF1 RNA or CSF1 protein but did not have the translocation. The rheumatoid arthritis and reactive synovitis specimens showed localization of CSF1 RNA and protein to the synovial lining cells, implying a possible role for CSF1 in the pathogenesis of these lesions. As the CSF1 translocation is postulated to play an important role in the biology of PVNS/TGCT, the consistent presence of CSF1 expression in translocation-negative cases implies that other mechanisms can lead to CSF1 up-regulation. The consistent presence of CSF1 overexpression in all cases of PVNS/TGCT and reactive synovitides suggests both an important role for CSF1 in the spectrum of synovial pathologies and the possibility of targeting the CSF1/CSF1R interaction therapeutically.

Imatinib mesylate induces mitochondria-dependent apoptosis and inhibits invasion of human pigmented villonodular synovitis fibroblast-like synovial cells.

Pigmented villonodular synovitis (PVNS) is a rare sarcoma-like disorder characterized by synovial lesions proliferation and invasion to articular cartilage for which no effective treatments are available. Imatinib mesylate (IM) is known to exert antitumor activity in some tumors, but its effects on PVNS fibroblast-like synoviocytes (PVNS-FLS) and the specific mechanism involved remain to be established. In the present study, the in vitro effects of IM on cell proliferation and survival rates were investigated in PVNS-FLS. Apoptosis induction was assessed via acridine orange/ethidium bromide (AO)/(EB) and Annexin V/PI staining as well as western blotting. The invasion ability of PVNS-FLS was evaluated by Transwell invasion chambers. IM significantly inhibited survival and invasion ability of PVNS-FLS in a dose- and time-dependent manner. The drug-treated cell groups exhibited markedly higher apoptosis, which was blocked upon pretreatment with the specific caspase-9 inhibitor Z-LEHD-FMK. Expression of cleaved caspase-9 was significantly increased and the Bcl-2 family and caspase-3 were activated following treatment with IM. Our results collectively demonstrated that IM has a strong antiproliferative effect on PVNS-FLS in vitro, attributable to induction of mitochondrial-dependent apoptosis in association with activation of caspase-9/-3 and the Bcl-2/Bax family, and exhibits significant inhibition on the invasion ability of PVNS-FLS, suggesting that IM may be useful as a novel treatment of this disease.

The catalytic activity of iron in synovial fluid as monitored by the ascorbate free radical.

Human synovial fluid, from a patient with synovitis disease, was examined by electron spin resonance spectroscopy for evidence of free radicals. The ascorbate free radical was observed and its intensity was affected by iron chelating agents, demonstrating that the iron in the synovial fluid is indeed available for oxidative catalysis.

Diffuse-type giant cell tumor: clinicopathologic and immunohistochemical analysis of 50 cases with extraarticular disease.

The clinical and pathologic features of 50 cases of diffuse-type tenosynovial giant cell tumor (D-TGCT), also known as extraarticular pigmented villonodular tenosynovitis (PVNTS), are presented. Patients' ages ranged from 4 to 76 years (median, 41 yrs), with a slight female predominance (28 women, 22 men). By definition, all lesions presented as predominant soft tissue masses, with or without an associated articular component. Tumor sites included the wrist (9 cases), knee (8 cases), thigh and foot (6 cases each), finger (5 cases), ankle (3 cases), hand, elbow, toes, buttock, paravertebral region (2 cases each), lower leg, sacrococcygeal area, and retroperitoneum; 27 cases were described as entirely extraarticular. Tumors showed infiltrative margins and, in most cases, a sheet-like growth pattern. Striking variation in the number of osteoclast-like giant cells, foamy cells, amount of hemosiderin, and in the degree of stromal hyalinization were responsible for a wide morphologic spectrum. In addition to the predominant histiocyte-like cells, we identified in most cases a subpopulation of large dendritic, desmin-positive cells showing characteristic, but potentially misleading, cytologic features, including abundant eosinophilic cytoplasm, large vesicular nuclei, paranuclear eosinophilic inclusions, and occasional nuclear inclusions. Follow-up information was available for 24 patients, with a duration ranging from 6 months to 30 years (mean, 55 mos). Local recurrence occurred in eight cases (33%), between 4 months and 6 months after surgery (median, 15 mos) and was repeated in five cases; recurrence did not appear to correlate with morphologic parameters. Six cases showed atypical histologic features and four of these contained areas of sarcomatous change. Among the latter, one of three cases with available follow up developed pulmonary metastases and died after 35 months. In addition, one histologically benign lesion gave rise, after two local recurrences, to inguinal and iliac lymph node metastases. Despite this exceedingly uncommon event, we think most cases of D-TGCT are best regarded as benign but locally aggressive neoplasms with significant recurrent potential and should be treated, when possible, by wide excision. Atypical features such as increased mitotic activity, necrosis, spindling of the mononucleate cells, and cytologic atypia are not indicative of malignancy when present individually. This study also confirms the existence of malignant tenosynovial giant cell tumors, some of which are characterized by aggressive behavior.

Expression of cell cycle-related gene products in different forms of primary versus recurrent PVNS.

Expression patterns of cell cycle regulating gene products and Ki-67 in proliferating synovial cells of primary and recurrent pigmented villonodular synovitis (PVNS) in localized and diffuse lesions were examined by immunohistochemistry. Alterations of cell cycle-related proteins were seen in 98.7% of analyzed lesions. Both RB- and p53 pathways play a role in cell cycle dysregulation in PVNS. The RB pathway was more frequently altered in primary disease, while alterations of the p53 pathway seemed to be more important in recurrent lesions, regardless of the histomorphological type of disease. Ki-67 proliferation rate was elevated in recurrent tumors.

Giant cell tumor of tendon sheath and pigmented villonodular synovitis: immunophenotype suggests a synovial cell origin.

Giant cell tumor of tendon sheath (GCTS) and pigmented villonodular synovitis (PVNS) are common synovial "tumors." Their immunohistochemical profile, however, has not been well characterized, and uncertainty exists regarding their histogenesis and relationship to fibroma of tendon sheath. In an effort to clarify these uncertainties and to better define the immunohistochemical profile of GCTS/PVNS, we examined formalin fixed tissue from 35 specimens of GCTS, 12 specimens of PVNS, and three cases of reactive synovitis using avidin biotin complex (ABC) and streptavidin immunohistochemical methods. Antibodies to vimentin, CD68, HAM56, cytokeratins, EMA, S100, HMB45, leukocyte common antigen, CD34, desmin, and smooth muscle actin were used in the study. The proliferating mononuclear cells and surface synovial cells in GCTS/PVNS and reactive synovitis stained positively for CD68, HAM56, and vimentin only. Multinucleated cells stained for CD68, vimentin, and leukocyte common antigen. All other stains were negative. Our results suggest that GCTS/PVNS are tumors of synovial cell origin, and do not support an association between GCTS and fibroma of tendon sheath.

Synovial-type giant cell tumors of the vertebral column: a clinicopathologic study of 15 cases, with a review of the literature and discussion of the differential diagnosis.

Synovial and tenosynovial giant cell tumors only rarely arise in close proximity to the axial skeleton; to date, fewer than 30 examples have been reported in the English-language medical literature. In this report we describe the clinical, radiologic, histopathologic, and immunohistochemical findings in 15 cases retrieved from our files. The study group comprised 7 males and 8 females, ranging in age from 17 to 44 years (mean age, 32 years). The tumors involved the cervical (n = 11), thoracic (n = 1), lumbar (n = 2), and sacrococcygeal (n = 1) regions and ranged in size from 1.0 to 6.0 cm in greatest dimension (median size, 3 cm). Symptoms were present for 2 months to at least 2 years, with the most common complaint being pain localized to the spinal region (n = 12). Ten patients also had radicular symptoms. Radiologic studies, available for 11 cases, usually demonstrated a mass involving the posterior aspect of adjoining vertebrae. Bony abnormalities (including scalloping, erosion, and destruction), facet joint and soft tissue involvement, and extradural extension were typically present. Histologically, all tumors contained a proliferation of epithelioid (histiocytoid) cells, admixed with varying numbers of osteoclast-like giant cells, siderophages, xanthoma cells, lymphocytes, and some spindled fibroblast-like cells. Only 1 tumor had the classic villiform architecture of pigmented villonodular synovitis. The remaining 14 tumors had a nodular appearance with varying amounts of collagen. Seven of these had definite histological evidence of infiltrative growth, and 6 had some features that warranted concern for possible infiltration. Only 1 tumor had findings fully compatible with a localized synovial-type giant cell tumor/nodular (teno)synovitis. All tumors had mitotic activity, with mitotic counts ranging from 1 to 21 mitotic figures per 50 high-power fields (HPFs) (mean mitotic count, 5 mitotic figures/50 HPFs). Immunohistochemistry was performed on 5 tumors, and immunoreactivity was present for CD68, CD163, and vimentin. Limited immunoreactivity for muscle actin (HUC1-1) was also noted. Follow-up information was available for 9 of the 15 patients (60%). Five patients had no evidence of recurrent or persistent disease 4 months to 9 years after undergoing either a local excision with gross total tumor removal (with or without irradiation) or a wide en bloc resection. Four patients had persistent disease after undergoing either an incomplete resection or biopsy with spinal fusion procedure. All 4 of these patients had additional surgical intervention (accompanied by irradiation in 2 instances), but only one was known to be disease-free at last follow-up (10 years after gross total tumor removal). No patient has experienced a metastasis or died of disease. The best predictor of outcome was gross total tumor removal at the surgical outset.

Cell characterization of mononuclear and giant cells constituting pigmented villonodular synovitis.

The aim of this study was to determine the histologic and cellular characteristics of 2 cell types, mononuclear cells (Mos) and multinuclear giant cells (GCs), that predominantly constitute pigmented villonodular synovitis (PVS). Synovial tissues examined in this study were obtained from 10 patients with PVS. Five methods were used for cell analysis: (1) enzyme-histochemistry for tartrate-resistant acid phosphatase (TRAP); (2) immunohistochemistry using antibodies for CD68, macrophage colony-stimulating factor (M-CSF), MIB-1, p53, p21, p16, and cathepsin-L (cath L); (3) TdT-mediated deoxyuridine triphosphate-biotin terminal end labeling (TUNEL) as a measure of apoptosis; (4) fluorescence-based polymerase chain reaction single-strand conformation polymorphism analyses (FPCR-SSCP) to detect p53 gene mutations; and (5) in situ hybridization using gene-specific oligoprobes for matrix metalloproteinase (MMP)-2, MMP-9, receptor activator of nuclear factor kappaB ligand (RANKL), and calcitonin receptor (CTR). Both Mos and GCs were shown to express the macrophage/histiocyte marker CD68. In GCs, TRAP and CTR, both of which are known as characteristic phenotype markers of osteoclasts, were expressed. M-CSF and RANKL, which are together essential for osteoclast differentiation, were expressed in both Mos and GCs. Mos were shown to express MIB-1, but GCs were not. Although proliferation-suppressor proteins p53, p21, and p16 were expressed in both Mos and GCs, little apoptotic phenomenon of lining Mos was detected by TUNEL. In our study, p53 gene mutations for exons 5, 7, and 8 in PVS synovial tissues were not detected by FPCR-SSCP analysis. Furthermore, both types of cells demonstrated the proteolytic enzymes MMP-2 and MMP-9 mRNA, and cath L protein. These results suggest that PVS has a hyperplastic property consisting of the CD68-positive monocytic cell lineage with differentiation of osteoclastic giant cells from monocyte and probably controlled against proliferation by wild-type p53, p21, and p16.

Comparative analysis of cell populations involved in the proliferative and inflammatory processes in diffuse and localised pigmented villonodular synovitis.

The aim of the present study was a comparative quantitative evaluation of cell populations involved in the proliferative and inflammatory compartment in both localised and diffuse pigmented synovitis villonodularis (PVNS). 15 cases of each localised and diffuse PVNS were examined by flow cytometry, immunohistochemistry, double immuno-fluorescence and confocal microscopy with quantitative evaluation of CD3-, CD4-, CD8-, CD20-, CD57-, CD55-, CD68-, CD163- and h4Ph positive (+) cells. The proliferative compartment of localised and diffuse PVNS was mainly composed of double-positive CD68+/h4Ph+ (CD163+/CD55+) synoviocytes. The number of double-positive synoviocytes for macrophage and fibroblast markers was significantly higher in diffuse compared to localised PVNS. The accompanying inflammatory infiltrate showed a predominance of cytotoxic cells (CD8+, CD57+), whereby the number of CD3+ and CD20+ cells was significantly higher in localised PVNS. The number of CD57+ NK cells was significantly higher in diffuse PVNS. The proliferating macrophage- like synovial cells and the cytotoxic lymphocytes could contribute to the aggressive behaviour of localised and diffuse PVNS. Moreover, with regard to the quantitative differences in cell composition between diffuse and localised PVNS and their different clinical behaviour, further studies should continue to analyse localised and diffuse PVNS separately.

Expression of tyrosine kinase receptors Tie-1 and Tie-2 in giant cell tumor of the tendon sheath: a possible role in synovial proliferation.

We have recently demonstrated that Tie-1 and Tie-2 are expressed in synovial cells from rheumatoid arthritis (RA). To elucidate the possible involvement of Tie receptors in synovial proliferation, we analyzed their expression by immunostaining in five cases of giant cell tumor of tendon sheath (GCTTS), which represents a proliferating lesion of synovial cells. Strong immunoreactivity for both Tie-1 and Tie-2, regardless of the individual patient's profile, was observed in all cases of GCTTS. Six sets of double immunohistochemical stainings for Tie-1/Tie-2 and fibronectin, CD68, or CD34 were carried out to determine the phenotype of Tie-1 and Tie-2-positive tumor components. In these studies, both Tie-1 and Tie-2 immunoreactivity were widely observed in the fibronectin-positive fibroblastic and the CD68-positive histiocytic mononuclear cells, as well as in the osteoclast-like giant cells. In tumor vasculature, Tie receptors were expressed in the CD34-positive endothelial cells possessing proliferating cell nuclear antigen (PCNA) immunoreactivity. We also evaluated the correlation of Tie-1/Tie-2 expression and proliferating cells in GCTTS by using double staining of Tie-1/Tie-2 together with PCNA. Overexpression of PCNA immunoreactivity was frequently found in Tie receptors-positive cells with no obvious differences in the expression pattern of Tie-1 and Tie-2. These findings suggest the possible involvement of Tie receptors in the pathogenesis of GCTTS other than solely via their involvement in angiogenesis and subsequent vascularization. It was demonstrated that Tie-2 immunoreactivity was restricted to the fibroblastic, but not histiocytic, phenotype in RA synovium, suggesting different regulatory control of Tie-2 expression in GCTTS and RA synovium. Overexpression of Tie receptors in GCTTS may imply a biological role for these receptors in synovial proliferation.

[Computertomographic findings in pigmented villonodular synovitis]. / Computertomographische Befunde bei der pigmentierten villonodulären Synovitis.

The CT findings in two patients with synovitis of the knee joint were analysed. Angiography is a non-specific method for the differential diagnosis of synovitis; CT, however, can be pathognomonic by showing a strikingly thick and hyperdense synovial membrane because of the iron content of the hyperplastic synovia. This is not found in non-specific synovitis.

MRI features of pigmented villonodular synovitis (PVNS).

The aim of this study was to characterize the magnetic resonance imaging (MRI) features of PVNS. The radiographs and MR images of 23 pathologically proven cases of PVNS were retrospectively reviewed, with emphasis on MR images. There were 9 males and 14 females, mean age 36 years. Of 23 cases, 9 occurred in the hip, 8 in the knee, 3 in the ankle, 2 in the elbow and 1 in the wrist. Typical MRI findings included variable extent of nodular synovial proliferation, from mild proliferation to extensive masses, joint effusion in all cases, and multiple bony erosions in 15. Owing to the tight joint space, bone involvement was frequently seen in the hip, ankle, elbow and wrist. Although the knee joint had a loose capsule, bone involvement was rarely seen. Hemosiderin is a magnetic material, its deposit on proliferative synovial tissue resulting in a spotty low signal or extensive low signal area within the proliferative synovial masses on T(1)- (T1WI) and T(2)-weighted (T2WI) images, best seen on fast field echo (FFE) sequence MRI images. Fat-suppressed sequences obscured the deposit. This is diagnostic of PVNS. The MRI features of PVNS include variable extent of synovial proliferation, joint effusion and erosion of bone, and in particular the deposit of hemosiderin within the synovial masses. The deposit of hemosiderin, appearing as a low signal area best seen on FFE sequence, is diagnostic for PVNS.

Intranuclear inclusions in a case of pigmented villonodular synovitis of the ankle.

Pigmented villonodular synovitis (PVNS) is a proliferative disorder of the synovial lining of the joints. Although the cytological findings of this disorder have been described in the literature, there is no mention of intranuclear cytoplasmic inclusions in this entity. A 65-yr-old woman presented with a painful swelling on the ankle. In addition to other characteristic findings of PVNS, we found the presence of intranuclear cytoplasmic inclusions in the fine-needle aspiration (FNA) smears. The characteristic cytological findings of abundant mononuclear cells occurring singly and in papillary clusters, multinucleated giant cells, and hemosiderin deposition should aid in the diagnosis of PVNS and in its differentiation from melanoma and other soft tissue sarcomas, even in the presence of uncommon features such as intranuclear inclusions.

MR imaging of pigmented villonodular synovitis of the knee.

Six cases of pigmented villonodular synovitis (PVNS) of the knee are presented. MR imaging and surgical proof were available in all cases. Three of the six cases showed the diffuse form, and the other three cases the localized form. The MR appearance of PVNS varied, presumably according to the relative proportion of pathological components. It most commonly consisted of scattered low signal intensity areas representing hemosiderin deposition in hypertrophied synovium on T2(*)-weighted images, and dotted areas of low signal intensity, presumably resulting from fibrous components of the lesion, on T1-weighted images. The latter finding is described for the first time in this report. Two cases were associated with osteoarthritis. In the remaining four cases, the osseous structures, cruciate ligaments, and menisci were normal. MR imaging was of great use in the detection of PVNS. For the first time, a preoperative diagnosis of PVNS of the knee joint could be made by MR imaging.