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Competing Interests: The authors declare no conflict of interest.

Ganglion cyst of the temporomandibular joint (TMJ) is an uncommon pathology with uncertain etiology. There is no consensus on their management. The current systematic review aimed to discuss the clinical and histopathological features of ganglion cysts of TMJ, to aid in appropriate treatment. A literature search was done and a total of 20 cases were retrieved from published databases such as PubMed, SCOPUS, and Google Scholar. The cyst presented with swelling in all the cases followed by pain (50 %) and trismus (35 %) as other common symptoms. Though CT and MRI proved helpful in determining the location of the cyst, a histopathological examination was essential in concluding its final diagnosis. It is a pseudocyst lined by dense fibro-connective tissue with myxoid tissue degeneration. Histologically, it is essential to distinguish them from the clinically and radiographically similar true cyst of TMJ, synovial cyst. The lining of ganglion cyst is devoid of epithelium and synovial cells. Surgical excision was found to be the treatment of choice with minimal recurrence (10 %) being reported., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Ganglion cysts in the knee region can manifest as anterior knee pain. Unlike synovial cysts, these lesions lack synovial epithelial lining and occur secondary to mucoid degeneration of connective tissue because, often in response to chronic irritation and repetitive traumas. However, an intratendinous location is a rare finding. In the knee region, infrapatellar fat pad, the alar folds, and the anterior cruciate ligament are recognized to degenerate into ganglion. There are few case reports describing an involvement of the patellar tendon. We present the clinical case of a 72 years old male patient suffering from anterior knee pain attributed to an intratendinous ganglion cyst of the patellar tendon, obviously after a single traumatic event. After aspiration of the ganglion cyst the patient reported no complaints, and there has been no recurrence during the latest follow-up examination.

Background: Spinal synovial cysts are lesions that most commonly occur in the lumbar region. The need for an instrumented spinal fusion in addition to lumbar decompression with removal of the synovial cyst is unknown., Objective: To test the hypothesis that select patients who underwent decompression with instrumented fusion for lumbar synovial cysts would be less likely to have subsequent surgery (SS) in a 2-year period than patients treated with laminectomy alone., Methods: This retrospective cohort study was performed using IBM MarketScan Commercial Claims and Encounters Database. Patients who had a lumbar synovial cyst diagnosis and laminectomy surgery with or without fusion surgery were included in this study. Patients were tracked for SS 2 years after surgery. Laminectomy patients were propensity score-matched to laminectomy with fusion (LF) patients using a 2:1 ratio. The log-rank test and Cox regression were used to compare the cumulative incidence of SS between groups., Results: There were 7664 and 1631 patients treated with laminectomy and LF before matching. After matching, there were 2212 laminectomy and 1631 LF patients and patient characteristics were balanced. The 2-year incidence of recurrent SS was 3.1% ([CI]: 2.2%, 4.0%) and 1.7% (95% CI: 0.9%, 2.5%) laminectomy and LF, respectively. Compared with laminectomy, LF had a statistically significant lower risk of recurrent SS (hazard ratio: 0.56 [95% CI: 0.32-0.97]; P -value: .04)., Conclusion: All patients who had concomitant lumbar fusion showed decreased chance of having a cyst- or noncyst-related recurrence SS when compared with all patients undergoing laminectomy alone, regardless of diagnosis at the time of SS., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)

Purpose: Ganglion cysts are benign soft tissue lesions found in joints, most commonly wrists. The incidence for juxtafacet cysts, the condition under which spinal ganglion cysts are categorized, is between 0.06% and 5.8%. Spinal ganglion cysts often arise in the most mobile segment of the lumbar spine, L4-L5. Patients commonly present with pain, radiculopathy, and weakness. Conservative management is used, but surgical resection is the most common treatment modality. We aim to review the literature and present a rare case of an L2-L3 situated spinal ganglion cyst, treated with maximal safe resection., Methods: A systematic review of literature was conducted in accordance with PRISMA guidelines. PubMed, Web of Science, and Cochrane databases were queried using Boolean operators and search terms, "spinal ganglion cyst, lumbar ganglion cyst, and lumbar juxtafacet cyst". Presentation, surgical management, and postoperative course of a 29-year-old male with an L2-L3 spinal ganglion cyst are also described., Results: The search yielded 824 articles; 23 met inclusion criteria. These papers consisted of 27 spinal ganglion cyst cases with disaggregated patient data. 63.0% of patients were male, and 53.4 years (range: 23-86) was the average age at presentation. Mean symptom duration was 1.9 years (range: 3 days-12 years). 70.4% of patients reported complete symptom resolution. 14.8% of cases noted neural foramen involvement., Conclusions: Spinal ganglion cysts are benign lesions typically presenting with radiculopathy. Maximal safe resection is an effective treatment modality with low complication rates. Future studies are needed to understand if neural foramen involvement leads to increased symptom severity., Competing Interests: Declaration of Competing Interest All authors declare that they have no personal, financial, or institutional conflict of interest., (Copyright © 2022. Published by Elsevier B.V.)

Temporomandibular joint (TMJ) synovial cysts are rare, unlike peripheric locations like the wrist or the knee. They share similar presentations with ganglion cyst, benign and sometimes malignant lesions. Only histopathological analysis confirms diagnosis in some cases, finding a true cyst lined by synoviocytes containing synovial fluid. They seem to be related to an increased articular pressure following trauma. In this study we present two cases of TMJ synovial cyst and a systematic review of the literature. A total of 32 cases were retrieved from published literature in PubMed, Cochrane Library and ClinicalTrials.gov databases using the search terms 'TMJ synovial cyst', 'temporomandibular synovial cyst', 'jaw joint synovial cyst'. Swelling (91.3%) and pain (78.3%) were the most common symptoms. MRI was the most commonly used imaging modality that was found to be beneficial for diagnosis. In almost all cases the cyst was removed under general anesthesia, allowing histopathological examination. Only two patients still had pain after removal of the cyst. No recurrence was observed ., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

Of Background Data: Despite a good understanding of the natural history of spinal synovial cysts (SCs), a widespread agreement regarding their optimal management is still lacking. This is particularly true for SCs occurring at the C1-C2 level, which are rare, but oftentimes lead to a rapidly evolving cervical myelopathy., Methods: We report a series of 4 patients (M:F ratio=1:1; mean age 63.5 years) presenting with progressive cervical myelopathy secondary to ventrally located C1-C2 SCs. All patients underwent a postero-lateral facet-sparing intradural approach with total excision of the SCs. Functional status was assessed pre- and postoperatively with Nurick scale and the modified Japanese Orthopaedic association grading. Furthermore we conducted a systematic review, following PRISMA guidelines of pertinent literature to contextualize the options for surgical management of such lesions., Results: Complete excision of the SCs was confirmed radiologically and on histological analysis. All measures of functional status improved post-operatively, and no cyst recurrence or need for instrumented fusion were noted during follow up (range from 22 to 88 months)., Conclusion: Our experience suggests that the facet-sparing intradural approach provides excellent clinical outcomes without causing any C1-C2 instability. This is in keeping with the take home message emerging from our literature review, which confirms that treatment should aim at radical resection of SCs while minimizing the risk of postoperative instability., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

This report describes the clinical and pathologic characteristics of cystic and myxomatous lesions of synovial joints in 16 cats. The average age was 13.4 years. The elbow was most commonly affected (12/16), and all lesions were unilateral. Degenerative joint disease was a frequent concurrent but bilateral condition. The lesions consisted of fluid-filled cysts lined by synoviocytes (3 cases), solid foci of stellate cells in a myxomatous matrix (2 cases), or a combination of the two (11 cases). In some cases there were areas of transition between the cystic and myxomatous lesions. Mitoses and other features of malignancy were rare to nonexistent. In the 13 cats with follow-up information, the lesion gradually increased in size over a period of years. None of the cats died or were euthanized because of this lesion. We propose that some cats with degenerative joint disease develop synovial cysts, which have the potential to transform to a synovial myxoma.

Purpose: Facet cysts develop due to degeneration of the zygapophyseal joints and can lead to radiculopathy and neurogenic claudication. Various surgical options are available for facet cyst excision. The aim was to facilitate surgical treatment of lumbar facet cysts based on a new classification., Methods: We retrospectively analyzed all patients of the last 10 years in whom a facet cyst was surgically removed (ipsilateral laminotomy, contralateral laminotomy, and segmental fusion). Several radiological parameters were analyzed and correlated with the patients' outcome (residual symptoms, perioperative complications, need for re-operation, need for secondary fusion, facet cyst recurrence)., Results: One hundred eleven patients (55 women; median age 64 years) could be identified. Thirty-three (48%) of 69 cases, for which MRI data were available, were classified as medial facet cyst (compressing the spinal canal), 6 facet cysts were localized intraforaminal (9%) and 30 cases (43%) mediolateral (combination of both). The contralateral approach had the lowest rate for revision surgery (7.5%, p = .038) and the lowest prevalence of residual complaints (7.5%, p = .109). A spondylolisthesis and a higher/steeper angle of the facet joints were associated with poorer patient outcome., Conclusions: Lateral facet joint cysts are best resected by a contralateral approach offering the best outcome while medial cysts are suitable for removal by an ipsilateral laminotomy. The approach of mediolateral cysts can be determined by the width of the lamina and the angle of the joint. Segmental fusion should be considered in cases with detected spondylolisthesis and/or steep facet joints.

Intraspinal synovial cyst (ISC) is a well-documented pathology. It is sometimes found in the degenerative lumbar spine and can result in neurological disorders. ISC typically contains xanthochromic fluid, blood, inflammatory tissue, and/or osseous structures, enclosed by fibrous tissue. Regarding the treatment modalities, the effectiveness of both nonsurgical management, such as oral analgesics, needle aspiration, and intra-articular injection of corticosteroid drugs, and surgical management, have been reported. Previous studies have described that the ISC can contain gas, which is derived from the vacuum phenomenon of an adjacent facet joint; however, this clinical condition has never been systematically investigated because of its rarity. In the present report, we describe the case of a 68-year-old male with gas-containing ISC in the lumbar spine who was successfully treated with surgical management; additionally, we performed a literature review to discuss the decision-making process for cases of gas-containing ISC. Based on our findings and previous literature, we recommend that considering the peculiarity of the content of such lesions in addition to the ball-valve effect of a synovial cyst, prompt transition to surgical management would be pertinent when nonsurgical treatment cannot achieve satisfactory outcomes in such cases., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Aim: To evaluate the factors affecting the clinical and radiological findings of juxtafacet cyst patients., Material and Methods: Between January 2011 and December 2018, eight patients diagnosed with juxtafacet cyst were reviewed, retrospectively. Patient demographics; signs and symptoms; and neurological examination, radiological, and surgical findings were noted., Results: The mean age was 54 years (range, 34â€"69 years) with five (62.5%) females and three (37.5%) males. There were nine juxtafacet cysts in eight patients. Five cysts (55.5%) were located at the L3â€"L4 level, two cysts (22.2%) at the L4â€"L5 level, and two cysts (22.2%) at the L5â€"S1 level. In all patients with L3â€"L4 cysts, the intercrest line was intersecting the spinal column at L4 vertebral body level. The most frequent symptoms were back pain and radiculopathy. Magnetic resonance imaging and computerized tomography revealed degenerative facet arthropathy in six patients (75%). Three patients (37.5%) had a medical history of trauma. One patient (12.5%) was treated conservatively. Seven patients (87.5%) were advised to undergo surgical treatment., Conclusion: Degeneration and instability are the main causes of juxtafacet cysts. They are mainly seen at the L4â€"L5 level due to higher movement capacity of this level. But, if the intercrest line intersects the spinal column at higher levels, degeneration and instability risks move to upper levels, and juxtafacet cysts may occur at the L3â€"L4 or upper levels.

Background: Hemorrhage is a rare presentation of spinal synovial cysts, which are usually located in the lumbar spine. They may cause an epidural hematoma and compression of the cauda equina. Infrequently, they may be located in the thoracic spine., Case Description: We present a case of sudden onset paraparesis caused by hemorrhage in a synovial cyst at a midthoracic level. Clinical, radiologic, and histologic findings are described., Conclusions: This report describes a unique case of hemorrhagic synovial cyst at the mid-thoracic spine. These lesions are rarely located in the cervico-thoracic spine but should be included in the differential diagnosis of myelopathy., (Crown Copyright © 2019. Published by Elsevier Inc. All rights reserved.)

Background: Extradural intraspinal cysts are fluid accumulations that appear to be associated with increased motion at vertebral joints., Case Presentation: We report the spontaneous regression of lumbar and lumbosacral cysts (presumably synovial cysts) and the unusual occurrence of an S1-2 extradural intraspinal cyst in a dog. The dog presented with lumbosacral pain. Six extradural intraspinal cysts were observed on high-field magnetic resonance imaging from L5-6 to S1-S2. The cysts between L5-6 and L7-S1 ranged from 0.12 to 0.44cm 2 at their largest area. The largest cyst was located at S1-2 (left), measuring 0.84 cm 2 at its largest view. The dog was medically managed. A follow-up magnetic resonance imaging scan was obtained 3.5 years after the first imaging. All cysts except the one at S1-2 had reduced in size. Mean reduction in size was 59.6% (35-81%)., Conclusions: In summary, we report a case with multiple extradural intraspinal cysts that underwent spontaneous regression of all but one cyst during a 3.5-year follow-up period. Whether this is a single occurrence, or is part of the natural history of these cysts in the lumbosacral region of dogs, remains to be established. Spontaneous regression of intraspinal cysts had not been described in dogs.

Background: Intraspinal lumbar vertebral joint cysts are an unusual cause of nerve root compression symptoms and do not differ clinically from the symptoms of a herniated disc., Pathogenesis: The cysts originate from the small vertebral joints and, depending on their size, compress the nerval structures. The affected vertebral joints typically show activated arthritic circumstances, which are associated with degenerative spondylolisthesis in about 50% of cases. In the majority of cases, MRT and CT can be used for diagnostic purposes. The exact etiology has not been fully clarified; various factors such as activated arthritis of the vertebral joints appear to be the major cause., Treatment: Treatment options include conservative, semi-invasive and surgical therapy. Conservative and semi-invasive treatment methods lead to temporary improvement. The result of surgical treatment, however, is excellent in a complete resection of synovial cysts. In In rare cases, an initial fusion is necessary in rare cases.

Synovial cysts very rarely affect the temporomandibular joint (TMJ). On review of the literature, there are 29 reported cases of unilateral synovial cysts of the TMJ. We present a case of bilateral synovial cysts occurring at the TMJs., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

Purpose: Synovial cyst of knee cruciate ligament (SCKCL) is a rare condition but can cause severe knee pain. The understanding of its etiology is relatively poor. This current study aimed to elucidate the pathogenesis of SCKCL based on a series of histo- and cytopathological examination., Methods: Ten SCKCL patients who underwent arthroscopy were enrolled, among five patients claimed past knee injury. Hematoxylin & eosin staining was conducted to the cyst wall tissue sections and Papanicolaou staining to the cyst fluid smear. Prussian blue staining was employed to both the wall section and fluid smear. Immumohistochemical staining for mesothelial cells (MC), epithelial cells (CK), vascular endothelial cells (CD31), monocytes (CD68), and hematogenous stem cells (CD117) were taken to elucidate the possible involvement of various cell types in the development of SCKCL., Results: No erythrocyte was discovered in the fluid; however, Prussian blue stained hemosiderin particles were found in the cyst wall and fluid, suggesting past hemorrhage in all patients. Abundant lymphocytes and plasmocytes were observed in the cyst wall and fluid. In addition, the cyst lining was infiltrated with abundant CD68(+) monocytes while only few MC(+) mesothelial cells were sporadically observed in four samples. The cyst submucosa was also diffused with abundant CD68(+) monocytes and proliferated capillaries stained with CD31. CD117-positve hematogenous stem cells were sporadically observed in eight specimens., Conclusion: Our findings provided evidence that SCKCL is not a mature synovial cyst but rather an inflammatory pseudo-cyst. It may have resulted from past minor hemorrhage and intra-ligament chronic inflammation.

Background: Isolated hypoglossal nerve palsy caused by an atlantooccipital synovial cyst is a rare lesion, with fewer than 5 cases reported in the literature., Case Description: Our patient presented with acute hypoglossal nerve dysfunction. Our differential included neoplasm, trauma, stroke, multiple sclerosis, or other inflammatory/infectious etiology. Imaging revealed a peripherally enhancing, extradural focus in the left premedullary cistern, most likely consistent with a synovial cyst., Conclusions: A left suboccipital craniectomy was performed in the region of the left hypoglossal canal, in which a cystic structure was noted at the occipital condyle and C1 vertebral junction. The nerve was adequately decompressed via aspiration of the cyst. Postoperatively, the patient substantially improved. Although rare, synovial cysts must be included in the differential diagnosis of atlantooccipital lesions., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Metaplastic synovial cyst (MSC) is a benign cystic lesion observed after surgical intervention and recurrent skin trauma. Because of its rarity, the etiology is not fully understood. The most emphasized etiologic factors are recurrent surgical procedures and cutaneous pathologies, which cause cutaneous fragility and abnormal wound formation. In the literature, MSC is exemplified as a mass that can be observed by the naked eye and palpated. All patients had a history of previous surgical procedures in the area. In the present case, we report a 48 -year-old woman with recurrent carpal tunnel syndrome due to a MSC. This report showed that MSC can be detected at deeper locations than the regions described in the literature. To our knowledge, this is the first report of MSC causing carpal tunnel syndrome recurrence. It is thought that previous operations are the most important etiologic factor in MSC occurrence., (Copyright © 2018 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.)

Although the nail is a small anatomical structure, it can be affected by various tumors and tumor-like conditions. Because of the distinctive nail anatomy, the clinical presentation of tumors is modified, thus rendering the diagnosis challenging. As nail biopsy and surgery are painful procedures associated with an increased risk of permanent onychodystrophy, pre-operative diagnosis is desirable. Although conventional radiographs are still the first-line radiologic examination for the assessment of bony structures beneath the nail matrix, they do not allow detailed evaluation of the phalangeal soft tissues. High resolution MRI allows accurate detection and mapping of nail lesions and can suggest a specific diagnosis. This review focuses on high resolution MRI of nail tumors and tumor-like lesions. We review the nail anatomy and the optimal MRI protocol. We then discuss a variety of tumors and tumor-like lesions in relation to the clinical presentation, anatomic location, histological features and imaging characteristics. We herewith describe common benign tumors (glomus tumor, onychomatricoma, keratoakanthoma, fibroma, subungual exostosis, hemangioma, chondroma, pyogenic granuloma), malignant tumors (subungual melanoma, subungual squamous cell carcinoma), as well as tumor mimics (mucoid cyst, epidermoid cyst). Although not entirely specific, MRI is a valuable tool in treatment planning of these tumors., (Published by Elsevier B.V.)

Rationale: Compressive radial neuropathy by a synovial cyst in the radial tunnel during pregnancy is a rare occurrence. The management of radial nerve compression caused by a synovial cyst in a pregnant patient is a surgical dilemma owing to the fetal and maternal risks of treatment., Patient Concerns and Diagnosis: A 37-year-old pregnant woman presented with progressive forearm pain at the gestational age of 12 weeks. A cyst was identified via musculoskeletal ultrasound and magnetic resonance imaging examinations in the radiocapitellar joint causing radial compressive neuropathy., Interventions: After regional nerve block and surgical removal of the cyst, the patient's forearm pain was alleviated without neurological deficits., Outcome: symptoms from nerve compression were improved after surgical treatment LESSONS:: This report illustrates the case of a pregnant woman presenting a compressive neuropathy by an enlarged cyst possibly due to the unbalance of growth factors during pregnancy. With proper diagnosis and timely surgical intervention, such patients can achieve good neurologic recovery without maternal or fetal complications.

Synovial cysts are benign tissue masses that develop near joints and tendons as a result of fluid leakage. They can be difficult to eradicate, and adjacent tendon and joint surfaces can complicate their treatment. We retrospectively analyzed the data from 4 consecutive patients who had undergone hallux interphalangeal fusion from January 2009 to December 2010. Of the 4 patients, 3 were male and 1 was female, with a mean age of 55 ± 22 (range 26 to 79) years. These 4 patients had developed painful interphalangeal arthritis with radiographic cystic changes of 1 to 4 years' duration. All patients were treated at a single facility, with surgical fixation of the joint performed by insertion of a single 4.3-mm headless lag screw across the interphalangeal joint. A final postoperative follow-up examination was performed at 22 ± 7 (range 14 to 30) months postoperatively. The mean American Orthopaedic Foot and Ankle Society hallux functional scores increased significantly from 70.8 ± 6.1 preoperatively to 90.5 ± 5.2 postoperatively (p < .01). No complications were observed, and complete interphalangeal joint fusion was observed at a mean of 9.2 ± 1.2 weeks. In conclusion, these preliminary data suggest that arthrodesis is an alternative effective treatment of symptomatic synovial cyst formation localized to the hallux interphalangeal joint., (Copyright © 2018. Published by Elsevier Inc.)

Cystic dilatation of synovial sheath, one of the targets of extra-hepatic manifestations associated with liver disease, is a main pathologic finding of lumbar synovial cyst (LSC). However, LSCs are not well documented in correlation with chronic viral hepatitis. In this case series, three patients with chronic viral hepatitis presented with radiating pain in the unilateral lower extremities. On magnetic resonance imaging of the lumbar spine, all had unilateral LSCs at the facet joint of the lumbar spine. Two did not have definite spinal instability at the LSC level. Ultimately, all three showed clinical improvements following epidural spine interventions., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Aims: Cystic lesions derived from the synovial and ligamentous structures of the spine have varied histological appearances. Not uncommonly, there is discrepancy between the clinicoradiological diagnosis and histology. Therefore, we sought to characterise the histological features of tissue submitted as 'synovial cysts' of the spine., Methods and Results: Resected specimens of the spine labelled 'synovial cysts' and 'lumbar cysts' were histologically evaluated and classified on the basis of histopathological features. Seventy-five histological samples of spinal cysts were identified. Thirty-one were classified as synovial cysts (definite synovial lining), 28 showed pseudocystic degeneration of the ligamentum flavum, seven showed pseudocyst formation without evidence of a synovial lining or degeneration of the ligamentum flavum, and eight showed cyst contents only or no histological evidence of cyst wall for evaluation. Twenty-five cases (33%), especially those showing pseudocystic degeneration of the ligamentum flavum, were associated with very characteristic tumour calcinosis-like calcium deposition with a surrounding foreign-body giant-cell reaction., Conclusion: Histology of 'synovial cysts' of the spine shows varied types of cyst; a large proportion are not synovial-lined cysts, but rather show pseudocystic degenerative changes of the ligamentum flavum, often associated with very characteristic finely granular calcifications and a foreign-body giant-cell reaction. This may have implications not only for understanding the pathogenesis of these lesions, but also for their varied responses to non-surgical interventions., (© 2018 John Wiley & Sons Ltd.)

To classify facet joint cysts (FJC) which will assist in identification of patient groups to best fit with a particular intervention. Sagittal T 2 -weighted magnetic resonance images (MRI) of these patients are used to measure cyst size, while axial T 2 -weighted MRI are used to determine the percentage of the vertebral canal occupied by the cyst. The degree of spondylolisthesis is also measured through standing X-rays or sagittal MRI. The proposed grading system is as follows. Grade I includes cysts that occupy less than 25% of the canal diameter that usually present with unilateral radiculopathy. Grade II includes cysts that occupy less than 50% of the canal diameter and may present with radiculopathy, with or without claudicant symptoms. Grade III cysts may present with radiculopathy and claudication with bilateral leg symptoms, along with facetogenic pain symptoms. Grades IV and V include potential instability as defined by greater than 15% spondylolisthesis in addition to either less than or greater than 50% canal stenosis. With higher grade cysts, presentation may include: facetogenic back pain, radiculopathy and claudicant pain in variable degrees of severity. The optimal classification system grades FJC from I to V on the basis of canal compression and degree of spondylolisthesis. Prospective studies are required to confirm the validity of this grading scale for long-term use., (© 2018 Chinese Orthopaedic Association and John Wiley & Sons Australia, Ltd.)

Lipoma arborescens is a rare intra-articular benign tumor. It affects mostly the knee and the diagnosis is usually difficult due to resembling symptomatology of osteoarthritis., Cases Presentation: We report herein 3 new cases of lipoma arborescens of the knee in which a patient has synovitis associated. In 2 cases, the discovery was intraoperatively. We also report a tumor relapse 2 years after surgery.

Background: Acute bilateral foot drop is a rare clinical presentation., Case Description: A 77-year-old male presented with acute bilateral weakness of the foot and ankle dorsiflexion. Magnetic resonance imaging of the lumbar spine revealed ligamentum flavum hypertrophy, as well as a mass lesion that appeared hyperintense on T1-weighted images and hypointense on T2-weighted images. Emergent decompressive laminectomy and hemorrhagic synovial cyst excision were performed. Histopathologic examination of the tissue revealed a synovial cyst with hemorrhage., Conclusion: Here, we describe a unique case of a hemorrhagic synovial cyst with a presenting symptom of acute bilateral foot drop., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Objective: The presence of findings at wrist MRI that may mimic disease is a diagnostic problem. The purpose of this study is to examine the occurrence of bone marrow changes resembling edema, joint fluid, and ganglion cysts over time, in a cohort of healthy children., Materials and Methods: Seventy-four of 89 healthy children included in a study of normal MRI findings of the wrists were reexamined after a period of 4 years, using the same 1.5-T MRI technique-namely, a coronal T1-weighted and a T2-weighted fat-saturated sequence. A history of handedness, diseases, and sports activity was noted., Results: Bone marrow edema or edemalike changes were seen in 29 of 74 (39.2%) wrists in 2013 as compared with 35 of 72 (48.6%) wrists in 2009 (p = 0.153), all in different locations. Changes were found in central parts of the bone, on both sides of a joint, or near bony depressions. Fifty percent of all subjects had at least one fluid pocket greater than or equal to 2 mm. The location was unchanged in 47% of the joints. In 24% of the individuals, at least one ganglion cyst was seen. Six ganglion cysts present on the first scan were not seen on the follow-up scan, and 11 new ganglion cysts had appeared., Conclusion: Awareness of normal MRI appearances of the growing skeleton is crucial when interpreting MRI of children, and such findings must not be interpreted as pathologic abnormalities.

Cutaneous metaplastic synovial cysts (CMSCs) are rare tumors typically comprising a solitary, well-circumscribed cystic mass that is not connected to the joint. Synovial cysts have been reported predominantly by orthopedists or pathologists; however, the presence of CMSC is not generally well recognized by dermatologists. Herein, we report a CMSC in a 68-year-old woman receiving systemic corticosteroid therapy for the treatment of eosinophilic granulomatosis with polyangiitis (EGPA). We attempt to delineate the clinical characteristics of this unusual neoplasm by reviewing the literature, focusing especially on dermatological descriptions. Histologic examination of the surgical specimen in the current case revealed that the cystic wall was lined with layers of flattened synovial cell-like cells and connective tissues, mimicking the synovial membrane. Positive immunoreactivity of the lining cells against vimentin was detected, but no immunoreactivity against cytokeratin, carcinoembryonic antigen (CEA), CD68, or S-100 was detected. The pathogenesis of CMSC remains unclear, but it has been tightly linked to direct traumatic stimuli or relative tissue fragility, which potentially accounts for CMSC development in our case. Most CMSCs reported by dermatologists are located on the extremities, whereas those described by other specialists tend to be distributed more globally. Preoperative diagnoses are often either epidermal cyst or suture/foreign body granuloma. Incomplete surgical excision of usual synovial cysts may lead to local recurrence, which has been reported in oral and maxillofacial surgery, but not in dermatologic surgery. This fact could be explained by the technical difficulties of surgical excision related to anatomical location. Dermatologists need to be aware of CMSC, and CMSC should be included in the differential diagnosis of subcutaneous cysts.

Background: Degenerative cystic lesions of atlantoaxial joints are rare and generally believed to be due to mechanical instability. There is currently no consensus on the management of such lesions in symptomatic and asymptomatic patients. Both conservative and surgical strategies have been described. Surgery may involve anterior or posterior approaches with and without decompression and instrumentation., Methods: We present a case report of a 45-year-old man who presented with new onset weakness and ataxia. Physical examination revealed decreased motor function in all extremities as well as positive Hoffman sign and ankle clonus bilaterally. An MRI of cervical spine showed a large atlantoaxial, T-2 hyperintense cystic lesion with cord compression and cord signal changes., Results: A C1 partial laminectomy was performed with resection of the cyst and C1-2 instrument fusion. Intra-operatively, the cystic lesion was found to be anatomically connected to the right C1-2 atlantoaxial joint with pathology showing fibroconnective tissue and chronic inflammatory changes. Post-operatively there were no complications and the patient was discharged to a rehabilitation facility. The patient was regaining gait and hand function by 3 months after surgery., Conclusions: Atlantoaxial synovial cysts are rare and the optimal surgical approach has not been determined. We further conducted a literature review and found a total of 70 other cases of atlantoaxial synovial cysts reported to date in the literature. We attempt to analyze available data and evaluate anterior versus posterior approaches and the need for decompression, amount of cyst resection, and instrumentation., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Lumbar synovial cysts are uncommon, and particularly rare at cervical levels. We report a 40-year-old woman who presented with pain distribution in the typical C6 dermatome. MRI revealed a right-sided large extradural cystic lesion adjacent to the C5/C6 facet joint that was hyperintense on T2-weighted MRI and hypointense on T1-weighted MRI. The patient underwent posterior cervical surgery at the C5/C6 level which involved posterior decompressive unilateral laminotomy and excision of the C5/C6 facet joint cyst. Following complete facetectomy of the right C5/C6 facet joint and exposure of the C6 nerve throughout its foraminal course, instrumented fusion was performed. Following the procedure, the patient had an uneventful recovery with relief of her radicular symptoms at follow-up clinical review., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Purpose: Differentiating between ganglion and synovial cysts by standard histology is difficult, leading to inaccurate statements on frequency for each of these periarticular lesions. The purpose of this study was to use immunohistochemical (IHC) analysis to 1) calculate the accuracy of the histologic diagnoses, 2) determine the frequency of ganglion and synovial cysts of the temporomandibular joint (TMJ), and 3) compare the frequency of these lesions in the TMJ compared with the extracranial skeleton in patients treated at Massachusetts General Hospital (MGH)., Materials and Methods: This is a retrospective cohort study of all patients undergoing treatment of TMJ cysts at MGH from 2001 through 2013. IHC analysis of tissue samples for each patient was completed and compared with the original histologic diagnoses. Categorical variables, including age, gender, and sidedness, were recorded. A natural language search of the MGH Department of Pathology database determined the frequency of extracranial periarticular cysts during the same period., Results: Thirteen patients met the inclusion criteria. Eleven cysts were synovial and 2 were ganglion based on histology. IHC analysis identified 2 false-positive synovial cyst diagnoses, resulting in 100% sensitivity and 50% specificity for the original histologic assessment and a percentage error of 22%. Of the periarticular TMJ lesions, 69% were synovial cysts and 31% were ganglion cysts. The frequency of TMJ versus extracranial ganglion cysts was 0.24%, and the frequency of TMJ versus extracranial synovial cysts was 0.60% based on 3,176 extracranial cysts (1,506 synovial; 1,670 ganglion)., Conclusion: This study represents the largest single-institution experience with periarticular cysts of the TMJ, and contrary to previous reports, TMJ cysts appear to be more frequently synovial than ganglion. IHC can be used to overcome the relatively poor specificity of histologic diagnosis of synovial cysts., (Copyright © 2016 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Three German Shepherd Dogs that were presented for investigation of chronic unilateral hindlimb lameness and pain in the lumbosacral region were diagnosed with an intraspinal, extradural synovial cyst and reactive fibrosis protruding into the foramen of the lumbosacral articulation using magnetic resonance imaging and histology. This extradural mass compressed the nerve root in the foramen and the cauda equina. During a dorsal laminectomy and unilateral partial foraminotomy, the cyst and the fibrotic tissue were removed with the aid of a 2.4 mm 30° arthroscope for visualization of the foramen. The fibrotic tissue surrounding the cysts was in all cases confluent with the annulus of the intervertebral disc. The histological examination confirmed the diagnosis of a synovial cyst in all three cases by finding inflamed synovial membrane in the samples from the wall of the cyst as well as reactive fibrosis and cartilaginous metaplasia in the surrounding tissue. The three patients improved after the surgery and were pain free during the follow-up evaluations.

Study Design: Case report., Objective: We report on a case with a retro-odontoid synovial cyst, and the immediate reduction of the cyst was confirmed after lateral atlantoaxial joint puncture and arthrography., Summary of Background Data: Retro-odontoid synovial cysts are rare diseases located posteriorly to a dense axis. Because most reports have focused on surgical treatment, only a few have examined nonsurgical treatment. However, several months are required after nonsurgical treatment until cyst regression., Methods: A 52-year-old female presented with atlantoaxial instability. She complained of neck pain and numbness in her hands. Magnetic resonance imaging revealed a retro-odontoid synovial cyst. Lateral atlantoaxial joint puncture and arthrography were performed., Results: Two days after treatment, the patient showed significant improvement in the numbness of her hands, and a follow-up magnetic resonance imaging revealed an immediate reduction in the cyst. During a 4.5-year follow-up period, no recurrence of the clinical symptoms occurred., Conclusion: Lateral atlantoaxial joint puncture may immediately reduce retro-odontoid synovial cysts, and the lateral atlantoaxial joint has a communication channel with the retro-odontoid synovial cyst via the atlantodental joint. Once disappearance of the cyst is confirmed, an acceptable long-term outcome can be achieved with nonsurgical treatment even in cases with atlantoaxial instability., Level of Evidence: N/A.

Ganglion cysts are common pseudocystic masses, whereas those arising from the temporomandibular joint (TMJ) are rare entities. We report a case of ganglion cyst of the right TMJ with symptomatic bilateral TMJ internal derangement in a 24-year-old man. Disk repositioning using bone anchors and excision of the ganglion cyst were performed. A unique characteristic of inflammatory infiltrates was revealed in the specimen, and the relationship between these 2 distinct entities and probable pathogenesis of infectious involvement are discussed.

Synovial cysts of the cervical spine are extremely rare. They can therefore pose a diagnostic challenge. We present an unusual case of acute symptomatology secondary to spontaneous haemorrhage into a cervical facet joint cyst.

Introduction: Gelatinous Heberden's nodes (HNs), also termed synovial cysts, are a common form of generalized osteoarthritis (OA). We sought to determine whether HN cases at clinical presentation contained multipotential stromal cells (MSCs) and to explore whether such cells were more closely related to bone marrow (BM) or synovial fluid (SF) MSCs by transcriptional analysis., Methods: At clinical presentation, gelatinous material was extracted/extruded from the distal phalangeal joint of OA patients with HNs. From this, plastic adherent cells were culture-expanded for phenotypic and functional characterization and comparison with BM- and SF-MSCs. Mesenchymal related gene expression was studied by using a custom-designed TaqMan Low Density Array to determine transcriptional similarities between different MSC groups and skin fibroblasts., Results: In all cases, HN material produced MSC-like colonies. Adherent cultures displayed an MSC phenotype (CD29(+), CD44(+), CD73(+), CD81(+), and CD90(+) and CD14(-) CD19(-), CD31(-), CD34(-), CD45(-), and HLADR(-)) and exhibited osteogenic, chondrogenic lineage differentiation but weak adipogenesis. Gene cluster analysis showed that HN-MSCs were more closely related to SF- than normal or OA BM-MSCs with significantly higher expression of synovium-related gene markers such as bone morphogenic protein 4 (BMP4), bone morphogenetic protein receptor type 1A (BMPR1A), protein/leucine-rich end leucine-rich repeat protein (PRELP), secreted frizzled-related protein 4 (SFRP4), and tumor necrosis factor alpha-induced protein 6 (TNFAIP6) (P <0.05)., Conclusions: Gelatinous HNs derived from hand OA at clinical presentation contain a population of MSCs that share transcriptional similarities with SF-derived MSCs. Their aberrant entrapment within the synovial cysts may impact on their normal role in joint homeostasis.

We present a patient with a relatively rare condition: Charcot joint of the shoulder, with a rare complication, the first known example of combined neurovascular compression in this location. A 49-year-old man presented with neuropathic arthropathy of the shoulder caused by syringomyelia from a Chiari I malformation, leading to compression of both the brachial plexus and the axillary vein by mass effect from the synovitis. The brachial plexopathy resolved with surgical decompression and synovectomy, and the syringomyelia stabilized after Chiari decompression. A large acromioclavicular joint synovial cyst developed as a late complication, which was treated nonoperatively. Understanding neuropathic arthropathy can explain the spectrum of interrelated typical and atypical features in this case over long-term follow-up., (Copyright © 2012 Wiley Periodicals, Inc.)

Background: Ganglion cysts of the cruciate ligament are rare and sometimes asymptomatic. The authors present three cases of ganglion cysts of the cruciate ligament with atlantoaxial subluxation, which has rarely been reported previously., Methods: Generally, ganglion cysts of the cruciate ligament are reported as case reports. Several theories regarding the process of cyst formation and the development of treatment options have been described. However, trans-oral decompression with total removal of the cyst may be one of the options for treatment of this kind of disease., Results: A retrospective review of three patients, two female and one male patient, with a mean age of 68 years was conducted. The operation performed was a trans-oral decompression with cyst removal for all patients. Clinical outcomes were evaluated after the operation. All patients underwent trans-oral decompression with total removal of the cyst, followed by posterior fusion and pathologic examination of the cyst, revealing myxoid stroma with an absence of synovial linings., Conclusion: The ganglion cysts and synovial cysts of the cruciate ligament are two different diseases with different presentation, pathogenesis, pathophysiology, and pathologic findings.

Background and Purpose: Lumbar facet synovial cysts are a cause of back pain and radiculopathy with facet joint degeneration, the most common cause for cyst formation. Typically, LFSCs are T2 hyperintense on MR imaging, but the signal intensity is variable. Treatment options include percutaneous rupture and surgical resection. This study evaluates the relationship between LFSC signal intensity on MR imaging and outcomes as it relates to percutaneous rupture success and need for subsequent surgery., Materials and Methods: A retrospective review of 110 patients who underwent CT fluoroscopic-guided rupture of symptomatic LFSCs was performed. The LFSCs were characterized by their T2 signal intensity on MR imaging and divided into 3 groups: high, intermediate, and low T2 signal intensity. The rates of successful cyst rupture and need for subsequent surgery were recorded., Results: Percutaneous LFSC rupture was technically successful in 87% of all cases. Cyst rupture was successful in 89% and 90% of high and intermediate signal intensity cysts, respectively, and in 65% of low signal intensity cysts (P = .017, .030). High signal intensity cysts had lower postprocedural surgical rates (29%) when compared with intermediate and low signal cyst as a group (P = .045)., Conclusions: T2 hyperintense and intermediate signal intensity LFSCs are easier to rupture, perhaps because the cysts contain a higher proportion of fluid and are less gelatinous or calcified than T2 hypointense cysts. Patients with T2 hyperintense LFSCs are less likely to need surgery.

Subaxial cervical facet cysts are uncommon. We report two patients with intraspinal, extradural, subaxial cervical spinal facet cysts, and review the literature to describe the epidemiology, clinical presentation, imaging findings, and treatment options for these lesions. Intraspinal, extradural, cervical spinal cysts should be considered as part of the differential diagnosis in patients presenting with clinical signs of cervical radiculopathy or myelopathy., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

A 67-year-old woman with rheumatoid arthritis (RA; Steinblocker stage IV, class 4) who had RA onset at 34 years of age had anterior thigh pain, femoral neuropathy and lower abdominal pain. Physical examination showed multidirectional limit of motion, and radiographic examination showed destruction of the hip joint. MRI and arthrography indicated a cystic lesion that communicated with the hip joint. The rheumatoid synovial cyst was removed during total hip arthroplasty. The symptoms were relieved, and the mass was reduced in size.

Cystic lesions are common around the knee and are often encountered as an incidental finding on routine magnetic resonance imaging examinations. The clinical presentation of cysts and other fluid collections is variable, depending on their size, location, and relationship to adjacent anatomic structures. This article reviews the anatomy, etiology, clinical presentation, and imaging features of commonly occurring cystic lesions around the knee and discusses some of the potential pitfalls that may be encountered in clinical practice., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Symptomatic lumbar synovial cysts (LSCs) are a rare cause of degenerative narrowing of the spinal canal, with thecal sac or nerve root compression. True synovial cysts have a thick wall lined by synovial cells, containing granulation tissue, numerous histiocytes, and giant cells. In contrast, pseudo-cysts lack specialized epithelium, have a collagenous capsule filled with myxoid material, and may be classified into ganglion cysts, originating from periarticular fibrous tissues, and ligamentous cysts, arising from the ligamentum flavum or even from the posterior longitudinal ligament. Here we present the surgical series of the Chair of Neurosurgery at the University of Cagliari (Italy) including a total of 17 LSCs. Surgical technique consisted of facet sparing excision of LSC, achieved by simple hemilaminectomy/laminectomy, and diagnosis was always confirmed by histological specimen examination, which detected the typical synovial epithelium, the intracystic presence of hemosiderin, histiocytes, and calcifications. Further immunohistochemical investigation revealed positive staining for cytokeratin: CK5, CK6, and AE1/AE3. Clinically, our cohort experienced rapid and complete resolution of symptoms, without perioperative complications, or recurrence of cysts or vertebral instability at a median follow up of 28 months, when the MacNab score was generally excellent. A review of the literature, retrieving articles published from 1973, collected a total of 101 articles concerning all the cases of LSC scientifically described to date. Both clinical and histological findings described in our study support the theory of degenerative microtraumatic pathogenesis of synovial cysts.