Synovial chondromatosis of the foot: Two case reports and literature review

BACKGROUND Primary synovial chondromatosis(PSC) is a rare arthropathy of the synovial joints characterized by the formation of cartilaginous nodules, which may detach and become loose bodies within the joint and may undergo secondary proliferation. PSC of the foot and ankle is exceedingly rare, with only a few cases reported in the literature. The diagnosis may be difficult and delayed until operative treatment, when it is confirmed by histological assessment. PSC may degenerate into chondrosarcoma. Operative treatment is the gold standard aiming to minimize pain, improve function, prevent or limit progression of arthritis. Surgical treatment consists in debridement by arthrotomic or arthroscopic management, but there is no consensus in the literature about timing of surgery and surgical technique. Thus, the aim of this study is to report the outcomes of the surgical treatment of two cases, together with a literature review.CASE SUMMARY We report two cases of patients affected by PSC of the foot in stage III, according to the Milgram classification: the former PSC localized in the ankle that underwent open surgery consisted of loose bodies removal;the latter in the subtalar joint, and the choice of treatment was the arthrotomy and debridement from loose bodies, in addition to the subtalar arthrodesis. Both patients returned to complete daily and working life after surgery.CONCLUSION Synovial chondromatosis is a rare benign pathology, even rarer in the ankle joint and especially in the foot. Surgery should be minimal in patients with ankle PSC,choosing the correct timing, waiting if possible until stage III. More aggressive and early surgery should be performed in patients with PSC of the foot,particularly the subtalar joint, due to the high risk of arthritic evolution.

Synovial chondromatosis of the hip joint in a 6 year-old child:A case report

BACKGROUND Synovial chondromatosis(SC)is a rare benign lesion first reported by Ambrose Pare in 1558.It is most common in the knee joint,followed by the hip joint and elbow joint.It is characterized by the presence of multiple pearl-like osteochondral bodies in the joint.The incidence in children is extremely low.CASE SUMMARY We report a 6-year-old Chinese boy who presented to our hospital with left hip joint pain and claudication for more than one year.We performed total surgical resection of SC tissue in the left hip.A good prognosis was confirmed at the 6-wk follow-up.Pain and swelling symptoms were totally relieved,range of motion of his left hip returned to normal,and there was no clinical evidence of lesion recurrence at last follow-up.Our case is the youngest reported patient with SC occurring in the hip.CONCLUSION SC is a rare disease and can be easily misdiagnosed.When we encounter children with hip pain and claudication,increased vigilance and a comprehensive physical examination and imaging examination should be considered,in order to avoid misdiagnosis and delayed treatment in patients.

Primary Combined Intra-articular and Extra-articular Synovial Osteochondromatosis of Shoulder: a Case Report

PRIMARY synovial chondromatosis is a rarecondition in which foci of cartilage develop in thesynovial membrane of joints, bursae and tendonsheaths. It typically involves a single large jointin a young adult male.1 The ectopic foci of cartilage canresult in painful joint effusion, and the generation of loosebodies can cause mechanical symptoms.2,3 The etiology ofprimary synovial chondromatosis remains unknown, butmetaplastic theory is the most popular hypothesis. Thecommonly involved joints are knee, elbow, and hip.^4 Theshoulder is a rare site of synovial chondromatosis2,3,5 andthe extra-articular involvement even rarer, with only fewcases presented in literature. This report presents a rarecase of primary combined intra-articular andextra-articular synovial chondromatosis of shoulder jointtreated with arthroscopy.

A Case Report of Synovial Osteochondromatosis of the Knee Joint with neither Calcification nor a Synovial Lesion on Imaging

Synovial osteochondromatosis is a rare, benign condition of unknown etiology in which the synovium undergoes metaplasia, leading to cartilaginous nodules that ultimately break free, mineralize, and even ossify. The most commonly involved joint is the knee. Typically, radiographs can be diagnostic and mineralized nodules are pathognomonic. In as many as one-third of cases, however, no calcification or ossification of the cartilage occurs in the early stage of the disease because mineralization is time-dependent. In such cases, gadolinium-enhanced MRI can be useful. Unmineralized nodules are typically peripherally enhanced because they are attached to and derive a vascular supply from the synovium. We experienced an unmineralized case of synovial osteochondromatosis of the right knee joint, in which imaging diagnosis was difficult. Neither calcification nor ossification was observed, but all nodules were released from the synovium as loose bodies and there was no vascular supply. Therefore, MRI did not show a typical appearance. These findings suggest that synovial osteochondromatosis should be considered as a differential diagnosis in a case in which unmineralized loose bodies without a synovial lesion are found in an imaging examination.

Synovial Chondromatosis of the Elbow Joint in a 27-Year-Old Man:A Case Report

Introduction: Multiple intraarticular loose bodies are pathognomonic for the Synovial chondromatosis. This disorder affects a wide age range from adults to childhood with no sex dominance. Malignant transformation is rare to date, and there are approximately 34 cases in literature about the transformation of synovial chondromatosis to chondrosarcoma. Case: We present case of a 27-year-old patient who had synovial chondromatosis in his elbow. Discussion: Radiographic findings are usually pathognomonic for the diagnosis. Multiple calcified loose bodies can be seen in the joint in radiographs. Computed tomography (CT) optimally depicts the calcified intraarticular fragments and extrinsic bone erosion. However, because the radioopacity cannot be detected in 1/3 of the cases, diagnosis becomes difficult. Treatment modalities include arthroscopic or open extraction of the loose bodies and arthropasty in the presence of severe osteoarthritis. Conclusion: Synovial chondromatosis should be kept in the differential dignosis of the chronic monoarticular pain and painful limitations of the range of motions of the joints.

Synovial Hemangioma in a 2 Year Old Mimicking Synovial Osteochondromatosis

We describe a rare synovial mass arising from the elbow of a 2 year old female. It was growing slowly for three months and there was no history of trauma or fever. Plain radiographs showed a soft tissue mass around the elbow with scattered nodular intraarticular calcifications. Ultrasound and MRI confirmed the synovial location of the mass and again showed the multiple calcifications, some of which suggested intraarticular loose bodies. The imaging findings were thought to represent synovial osteochondromatosis but subsequent biopsy revealed a synovial hemangioma and it is for this reason that we present our case.

Arthroscopic synovectomy for synovial hyperplasia in chronic knee gouty arthritis:A case report

BACKGROUND Chronic synovitis due to chronic knee gouty arthritis(KGA)resulting in synovial hyperplasia has not been documented in the current literature,and thus the optimal management for this condition remains unclear.This case report discusses a 34-year-old man with a history of chronic KGA who presented with recurrent knee effusion resulting from synovial hyperplasia.CASE SUMMARY A 34-year-old man presented to our outpatient clinic with a 5-year recurrent knee effusion and a history of chronic KGA.Symptoms persisted despite serial aspiration and urate-lowering medication(febuxostat 80 mg once daily)for 2 months.Diagnostic arthroscopy was performed due to the recalcitrant symptoms.Intraoperatively,tophi deposition and excessive thickening of the synovial membrane were observed.Synovial biopsy and partial synovectomy were performed,revealing chronic synovitis with synovial hyperplasia that was consistent with chronic KGA.At follow-up after 6 months,the patient reported no further episode of knee effusion.CONCLUSION Arthroscopic synovectomy for synovial hyperplasia in chronic KGA sufficiently eradicates the symptoms of recurrent knee effusion.

Treatment of Synovial Cysts in Relation to the Tibial Tunnel of Anterior Cruciate Ligament Grafts by Filling the Tunnel with Acrylic Cement

Introduction: Synovial cyst of the tibial tunnel in connection with anterior cruciate ligament (ACL) reconstruction is a rare but particularly troublesome complication. Medical treatment is often doomed to failure, and surgical treatment usually consists of excising the cyst and filling the tunnel with bone. The aim of this study was to evaluate the results of filling the tunnel with acrylic cement. Hypothesis: Filling the tibial bone tunnel with acrylic cement should eliminate communication between the joint cavity and the pre-tibial surface and prevent cyst recurrence. Patients and Methods: This retrospective series is composed of 13 patients, 9 men and 4 women, mean age 48.5 years (31 to 64) operated on between 2011 and 2019 for an intra- and extraosseous synovial cyst consecutive to the tibial tunnel of an ACL graft. Between 1983 and 2016, 12 of the patients had had a bone graft without bone block fixation (DI-DT or Mac Intosh) and one patient, a bone-bone transplant (KJ). The cyst was of variable size, located on the anteromedial aspect of the proximal end of the tibia, and often painful, warranting consultation. At the time of the initial operation, 9 patients had undergone meniscectomies (6 medial, 2 lateral, 1 double). In 7 knees, there were 7 cartilage lesions in the femorotibial and/or patellofemoral compartments (one stage 1 lesion, 2 stage 2 lesions, 4 stage 3 lesions, and no stage 4 lesions). Only 2 knees had neither cartilage nor meniscus lesions. After curettage of the bone tunnel /− removal of the non-resorbed or PEEK interference screw, the tunnel was filled with acrylic cement /− reinforced with a ligament staple to prevent expulsion. All patients underwent regular follow-up consultations until recovery. Results: At a maximum follow-up of 8 years, only 1 cyst recurred, representing a 7.69% failure rate. It was reoperated with another technique, which involved filling the tibial bone tunnel with bone graft taken from a half-bank head. After recovery, the cyst healed definitively. All patients were able to return to their previous activity within 15 days of surgery. Conclusion: Filling the tibial tunnel with acrylic cement reinforced /− with a ligament staple is a reliable and rapid solution for the treatment of intra- and extra-articular synovial cysts in relation to the tibial tunnel of ACL grafts.

Detection of the SYT-SSX Fusion Gene in Synovial Sarcoma

Objective: To investigate the feasibility and significance of detecting SYT-SSX fusion gene in paraffin-embedded tissues of synovial sarcoma (SS) by reverse-transcriptase polymerase chain reaction(RT-PCR) methods. Methods: Twenty cases of SS tumors from archival materials were collected and all samples were formalin-fixed and paraffin-embedded (FFPE). SYT-SSX fusion transcript was detected by RT-PCR. Home-keeping gene Porphobilinogen Deaminase (PBGD) was regarded as internal control.Results: PBGD mRNA was detected in all 20 tumor cases (100%). SYT-SSX fusion transcript was detected in 18 tumor cases (90%). In 18 SYT-SSX positive SS cases, there are 12 present SYT-SSX1 fusion transcript and 6 present SYT-SSX2 fusion transcript. SYT-SSX1 fusion transcript can be seen in 9 monophasic SS and 3 biphasic SS. In 6 SYT-SSX2 positive SS cases, 4 were monophasic SS and 2 were biphasic. Conclusion: Detection of SYT-SSX fusion transcripts in FFPE tissues for diagnosis of SS is feasible and sensitive. Subtypes of SYT-SSX fusion gene may provide prognosis information.

Arthroscopic surgery for synovial chondroma of the subacromial bursa with non-traumatic shoulder subluxation complications:Two case reports

BACKGROUND Synovial chondromatosis is a disease originating from the synovium and characterized by the presence of metaplastic cartilaginous nodules in synovial cavities.The exact prevalence of synovial chondromatosis remains unknown,and the involvement of the shoulder joint is very rare.Synovial chondromatosis accompanied by subluxation of the humeral head without a history of trauma is rarely encountered,and to our knowledge,no published reports describe this condition.CASE SUMMARY We present two cases of synovial chondromatosis in the shoulder joint,accompanied by subluxation of the humeral head,in two arthroscopically managed adult patients.We performed arthroscopic labrum fixation and removal of the loose body from the shoulder joint.To identify primary and secondary categories,pathological analysis was arranged.Clinical and radiographic evaluations at the 1-mo follow-up were satisfactory.CONCLUSION The biomechanical function of the shoulder joint requires attention,especially following the detection of loose bodies,as observed with synovial chondroma occurring in rare sites.Arthroscopic management is successful in patients with synovial chondromatosis combined with shoulder subluxation.

Solitary primary pulmonary synovial sarcoma:A case report

BACKGROUND Synovial sarcoma(SS)is an uncommon and highly malignant soft tissue sarcoma in the clinic,with primary pulmonary SS(PPSS)being extremely rare.Here,we describe the clinical characteristics,diagnosis,and treatment of a solitary PPSS case confirmed via surgical resection and fluorescence in situ hybridization(FISH).CASE SUMMARY A 33-year-old man was admitted because of intermittent coughing and hemoptysis for one month,with lung shadows observed for two years.Wholebody positron emission tomography-computed tomography(PET-CT)revealed a solitary mass in the upper lobe of the right lung,with uneven radioactivity uptake and a maximum standardized uptake value of 5.6.The greyish-yellow specimen obtained following thoracoscopic resection was covered with small multinodulated structures and consisted of soft tissue.Hematoxylin and eosin staining revealed spindle-shaped malignant tumor cells.Immunohistochemistry indicated these tumor cells were CD99 and BCL-2-positive.Furthermore,the FISH test revealed synovial sarcoma translocation genetic reassortment,which confirmed the diagnosis of SS.CONCLUSION PPSS is extremely rare and tends to be misdiagnosed as many primary pulmonary diseases.PET-CT,histologic analysis,and FISH tests can be used to differentiate PPSS from other diseases.Surgical resection is regularly recommended for the treatment of solitary PPSS and is helpful for improving the prognosis.

Expression of miRNA-140 in Chondrocytes and Synovial Fluid of Knee Joints in Patients with Osteoarthritis

Objective To investigate the expression of miRNA-140 in chondrocytes and synovial fluid of osteoarthritis(OA) patients, and explore the relationship between the miRNA-140 expression and OA severity. Methods This study enrolled 30 OA patients who underwent total knee arthroplasty for chondrocytes sampling and 30 OA patients who underwent intra-articular injection for synovial fluid sampling. All OA patients were grouped into mild [Kellgren and Lawrence(KL) grade 1-2], moderate(KL grade 3) and severe(KL grade 4), with 10 in each subgroups for each sampling purposes. 7 non-OA patients and 10 patients with knee injury were collected for cartilage and synovial fluid sampling respectively as control groups. Chondrocytes were isolated from the cartilage tissue and cultured in vitro. Quantitative real time PCR for miRNA-140 in chondrocytes and synovial fluid were performed, and the U6 sn RNA was used as internal control. The expression difference of miRNA-140 among groups and correlation between the expression and the KL grade of OA were analysed using one-way ANOVA and Spearman test respectively. Results The expression of miRNA-140 in chondrocytes of knees in OA patients was reduced than that in normal knees, and the between-group difference was statistically significant(F=305.464, P<0.001). miRNA-140 could be detected in synovial fluid of both normal knees and OA knees, its relative expression level was reduced in synovial fluid of OA group compared with normal group, and the between-group difference was statistically significant as well(F=314.245, P<0.001). The relative expression level of miRNA-140 in both chondrocytes and synovial fluid were negatively correlated with the KL grade of OA(r=-0.969, P<0.001; r=-0.970, P<0.001). Conclusion miRNA-140 could be detected in chondrocytes and synovial fluid of OA patients, and its expression was negatively correlated with the severity of OA.

Expression of NF-κ B and osteopontin of synovial fluid of patients with knee osteoarthritis

Objective:To explore the significance of osteopontin and nuclear factorκB(NF-κB) expression in patients with knee osteoarthritis.Methods:RT-PCR and enzyme-linked immunosorbent assay were used to measure the Osteopontin(OPN) and NF-κB concentration of knee joint synovial fluid of patients with knee osteoarthritis and trauma fractures,and analyze the relationship between the expressiones of them.Results:OPN and NF-κB expression at the mRNA and protein levels of patients with knee osteoarthritis were significantly higher than the control group, the result showed statistical significance(P【0.05).There was a positive correlation between the OPN levels in synovial fluid of patients with knee osteoarthritis and NF-κB expression levels (P【0.05).Conclusions:The high expression of OPN and NF-κB are closely related to occurrence and development of knee osteoarthritis.

Utility of arthroscopic guided synovial biopsy in understanding synovial tissue pathology in health and disease states

The synovium is the soft tissue lining diarthrodial joints, tendon sheaths and bursae and is composed of intimal and subintimal layers. The intimal layer is composed of type A cells(macrophages) and type B cells(fibroblasts); in health, the subintima has few inflammatory cells. The synovium performs several homeostatic functions and is the primary target in several inflammatory arthritides. Inflammatory states are characterised by thickening of the synovial lining, macrophage recruitment and fibroblast proliferation, and an influx of inflammatory cells including lymphocytes, monocytes and plasma cells. Of the various methods employed to perform synovial biopsies arthroscopic techniques are considered the "gold standard", and have an established safety record. Synovial biopsy has been of critical importance in understanding disease pathogenesis and has provided insight into mechanisms of action of targeted therapies by way of direct evidence about eventsin the synovial tissue in various arthritides. It has been very useful as a research tool for proof of concept studies to assess efficacy and mechanisms of new therapies, provide tissue for in vitro studies, proteomics and microarrays and allow evaluation for biomarkers that may help predict response to therapy and identify new targets for drug development. It also has diagnostic value in the evaluation of neoplastic or granulomatous disease or infection when synovial fluid analysis is noncontributory.

Detection of fusion gene in cell-free DNA of a gastric synovial sarcoma

Synovial sarcoma(SS) is genetically characterized by chromosomal translocation, which generates SYT-SSX fusion transcripts. Although SS can occur in any body part, primary gastric SS is substantially rare. Here we describe a detection of the fusion gene sequence of gastric SS in plasma cell-free DNA(cf DNA). A gastric submucosal tumor was detected in the stomach of a 27-year-old woman and diagnosed as SS. Candidate intronic primers were designed to detect the intronic fusion breakpoint and this fusion sequence was confirmed in intron 10 of SYT and intron 5 of SSX2 by genomic polymerase chain reaction(PCR) and direct sequencing. A locked nucleic acid(LNA) probe specificto the fusion sequence was designed for detecting the fusion sequence in plasma and the fusion sequence was detected in preoperative plasma cfD NA, while not detected in postoperative plasma cfD NA. This technique will be useful for monitoring translocation-derived diseases such as SS.

Primary renal synovial sarcoma: A case report

BACKGROUND Synovial sarcoma,a rare mesenchymal tumor type with unclear histological origin and direction of differentiation,accounts for 6%–10%of soft tissue tumors.It is mainly located near the joints and tendons of the limbs,and occurs primarily in children or young adults.Primary renal synovial sarcoma(PRSS)is very rare,accounting for approximately 1%of synovial sarcomas.It is a spindle cell tumor type affecting mesenchymal tissue,and has morphological,genetic,and clinical characteristics,and a certain degree of epithelial differentiation.It is highly malignant and has the fourth highest incidence among soft tissue sarcomas.Here,we report a case of PRSS and share some valuable information about the disease.CASE SUMMARY A 54-year-old male patient was admitted to the hospital for a space-occupying lesion in the right kidney for 2 d upon ultrasound examination.The patient had no cold or fever;no frequency,urgency or pain of urination;and no other discomfort.The results of a hemogram,blood biochemistry,and tumor markers were in the normal range.The patient was examined by computed tomography(CT),which indicated the presence of a soft tissue density shadow with a diameter of approximately 6.8 cm in the right renal pelvis area,showing uneven enhancement.Ultrasound indicated a cystic solid mass of approximately 6.8 cm×6.5 cm in the right kidney,with an unclear boundary and irregular shape.Meanwhile,color Doppler flow imaging showed dotted blood flow signals in the periphery and interior.Contrast-enhanced ultrasound(CEUS)showed"slow in and fast out"hyperenhancement of the right renal mass after contrast agent injection.The postoperative pathological diagnosis was(right kidney)synovial sarcoma.Despite postoperative adjuvant chemotherapy,tumor recurrence was detected two years later.CONCLUSION PRSS is a rare malignant tumor.To date,no characteristic imaging findings have been observed.The diagnosis is confirmed primarily through postoperative pathological immunohistochemistry and SS18(SYT)gene detection.In this case,CEUS was used preoperatively.We found that PRSS has the characteristic of"slow in and fast out"hyperenhancement,and its particular characteristics have diagnostic value.Postoperative adjuvant chemotherapy is not very effective.

Midline synovial and ganglion cysts causing neurogenic claudication

Typically situated posterolateral in the spinal canal, intraspinal facet cysts often cause radicular symptoms. Rarely, the midline location of these synovial or ganglion cysts may cause thecal sac compression leading to neurogenic claudication or cauda equina syndrome. This article summarizes the clinical presentation, radiographic appearance, and management of three intraspinal, midline facet cysts. Three patients with symptomatic midline intraspinal facet cysts were retrospectively reviewed. Documented clinical visits, operative notes, histopathology reports, and imaging findings were investigated for each patient. One patient presented with neurogenic claudication while two patients developed partial, subacute cauda equina syndrome. All 3 patients initially responded favorably to lumbar decompression and midline cyst resection; however, one patient required surgical stabilization 8 mo later. Following the three case presentations, we performed a thorough literature search in order to identify articles describing intraspinal cystic lesions in lateral or midline locations. Midline intraspinal facet cysts represent an uncommon cause of lumbar stenosis and thecal sac compression. Such entities should enter the differential diagnosis of midline posterior cystic lesions. Midline cysts causing thecal sac compression respond favorably to lumbar surgical decompression and cyst resection. Though laminectomy is a commonly performed operation, stabilization may be required in cases of spondylolisthesis or instability.

Influences of IL-6R Antibody on PMMA Bone Cement-mediated Expression of OPG and RANKL in Synovial Fibroblasts

Effect of interleukin-6 receptor （IL-6R） antibody on polymethyl methacrylate （PMMA） bone cement-mediated expression of osteoprotegerin （OPG） and ：receptor activator of nuclear fac- tor-kappaB ligand （RANKL） in synovial fibroblasts was investigated. Synovial tissue obtained from to- tal knee arthroplasty was digested and cultured. Inverted microscope was employed to observe the synovial cells and immunocytochemistry （SABC method） staining was used to identify synovial fibro- blasts. This experiment was divided into three groups according to different culture media： PMMA group （75μg/mL PMMA bone cement particles）, IL-6R antibody group （10 ng/mL IL-6R antibody＋75 μg/mL PMMA bone cement particles）, and control group （no IL-6R antibody or PMMA bone cement particles）. Influence of IL-6R antibody and PMMA on proliferation of synovial fibroblasts was meas- ured by cell counting kit-8 （CCK-8）. ELISA method was used to measure OPG and RANKL levels in culture solution. Fluorescence quantitative real-time PCR （FQ-PCR） was used to detect the expression of OPG and RANKL mRNA. After three consecutive passages, more than 95% of the primary synovial cells became long spindle fibroblast-like cells. SABC staining results showed that the fibroblast-like cells were negative for anti-CD68 antibody and positive for anti-vimentin antibody, with brown madder stained. CCK-8 test demonstrated that the absorbance （A） value at 450 nm was significantly lower in IL-6R antibody group than in PMMA group and control group （P〈0.01）, but there was no statistically significant difference in A value at 450 nm between the control group and PMMA group （P〉0.05）. Re- suits of ELISA indicated that the expression of OPG was significantly higher in IL-6R antibody group than in PMMA group and control group （P〈0.01）. The expression of RANKL was inhibited （P〈0.05）, and the ratio of OPG/RANKL was significantly increased in IL-6R antibody group as compared with PMMA group and control group. There was no significant difference in the expression of OPG between control group and PMMA group （P〉0.05）, but the expression of RANKL was higher in PMMA group than in control group （P〈0.05）, and there was a significant difference in the ratio of OPG/RANKL be- tween them （P〈0.05）. Results of FQ-PCR revealed the expression of RANKL mRNA was significantly inhibited （P〈0.01） and the expression of OPG mRNA was significantly increased （P〈0.01） in IL-6R an- tibody group as compared with PMMA group and control group. The expression of RANKL mRNA was higher in PMMA group than in control group （P〈0.05）, but the expression of OPG mRNA had no sig- nificant difference between them （P〉0.05）. IL-6R antibody could significantly increase the expression of OPC~ but inhibit the expression of RANKL, which might provide a theoretical basis of molecular bi- ology for the prevention and treatment of aseptic loosening of prosthesis.

Management of primary retroperitoneal synovial sarcoma: A case report and review of literature

BACKGROUND Synovial sarcoma(SS) is a rare type of soft tissue sarcoma that is usually developed from areas where synovial tissue exists, especially at the extremities.Nevertheless, several cases of retroperitoneal SS(RSS) have been described. We herein report a case of RSS presented in our institution.CASE SUMMARY A 69-year-old female patient was admitted with a large, palpable, firm mass in the right abdominal space SS. Computerized tomography scan depicted a concentric, sharply marinated retro-peritoneal lesion which was displacing the right kidney and the lower edge of the liver. Subsequently, the patient underwent surgical excision of the mass with additional right nephrectomy and resection of the right adrenal gland and a part of the diaphragm. The final histological diagnosis of the tumour was grade II monophasic RSS.CONCLUSION RSS is encountered in the biphasic type, the monophasic fibrous, and the monophasic epithelial category as well. Relevant clinical manifestations are not always documented at early stages. Therefore, the final diagnosis is posed after complete histological examination taking into consideration the results of immunochemistry and genetic analysis. Therapeutic approach happens often late when metastases at the lungs and the liver are apparent. Thus, 5-year survival rates remain low.

Synovial lipomatosis: A rare cause of knee pain in an adolescent female

Synovial lipomatosis is a benign proliferative disease of the subsynovial adipose which can lead to a variety of presentations. Cases of synovial lipomatosis in children or adolescents are rare. This case report describes an adolescent patient with a rare bilateral presentation of synovial lipomatosis. She had been treated for years prior to her presentation for juvenile idiopathic arthritis. She presented with chronic bilateral knee pain, swelling, and mechanical symptoms. Bilateral MR imaging demonstrated effusions, hypertrophy of the synovium, and polyp-like projections of tissue with the same signal intensity as fat which is pathognomonic for synovial lipomatosis. Arthroscopic synovectomy and extensive debridement of polyp like fat projections of the right knee was performed. Histopathology was consistent with the synovial lipomatosis diagnosis. Postoperatively, the patient was satisfied with her outcome with improved pain relief and function in her right knee.