Background Mesenchymal chondrosarcoma (MCS) is a rare malignant variant of chondrosarcoma with a high tendency of recurrence and metastasis. Intradural extramedullary spinal MCS is exceedingly rare and usually found in pediatric patients. Herein, we present an elderly patient with primary intradural extramedullary spinal MCS. Relevant literatures are reviewed to disclose characteristics of intradural extramedullary spinal MCS. Case presentation A 64-year-old female presented with urinary difficulty and tightness of upper back preceding progressive weakness of right lower extremity. Magnetic resonance imaging revealed an intradural extramedullary tumor at the level of 3rd thoracic vertebra. This patient underwent total tumor resection and then received adjuvant radiotherapy. Histopathological examination showed that the tumor composed of spindle and round cells with high nucleocytoplasmic ratio accompanied by scattered eosinophilic chondroid matrix. Along with immunohistochemical findings and the existence of HEY1-NCOA2 fusion transcript, the diagnosis of MCS was confirmed. Neurologic deficit recovered nearly completely after surgery. No evidence of local recurrence or distant metastasis was found 5 years after treatments. Including the current case, a total of 18 cases have been reported in the literature with only one case with local recurrence and one case of mortality. The current case was the eldest patient diagnosed with primary intraspinal MCS in the literature. Conclusions MCS rarely appears in the intradural space of the spine. In contrast to classic MCS, treatment outcome of primary intradural extramedullary spinal MCS is usually excellent as total tumor resection is commonly achievable. Adjuvant radiotherapy may reduce local recurrence and chemotherapy may be associated with fewer recurrences especially for unresectable tumors. Electronic supplementary material The online version of this article (10.1186/s12891-019-2799-2) contains supplementary material, which is available to authorized users.
Background Nuclear receptor interaction protein (NRIP) co‐localizes with acetylcholine receptor (AChR) at the neuromuscular junction (NMJ), and NRIP deficiency causes aberrant NMJ architecture. However, the normal physiological and pathophysiological roles of NRIP in NMJ are still unclear. Methods We investigated the co‐localization and interaction of NRIP with AChR‐associated proteins using immunofluorescence and immunoprecipitation assay, respectively. The binding affinity of AChR‐associated proteins was analysed in muscle‐restricted NRIP knockout mice and NRIP knockout muscle cells (C2C12). We further collected the sera from 43 patients with myasthenia gravis (MG), an NMJ disorder. The existence and features of anti‐NRIP autoantibody in sera were studied using Western blot and epitope mapping. Results NRIP co‐localized with AChR, rapsyn and α‐actinin 2 (ACTN2) in gastrocnemius muscles of mice; and α‐bungarotoxin (BTX) pull‐down assay revealed NRIP with rapsyn and ACTN2 in complexes from muscle tissues and cells. NRIP directly binds with α subunit of AChR (AChRα) in vitro and in vivo to affect the binding affinity of AChR with rapsyn and rapsyn with ACTN2. In 43 patients with MG (age, 58.4 ± 14.5 years; female, 55.8%), we detected six of them (14.0%) having anti‐NRIP autoantibody. The presence of anti‐NRIP autoantibody correlated with a more severe type of MG when AChR autoantibody existed (P = 0.011). The higher the titre of anti‐NRIP autoantibody, the more severe MG severity (P = 0.032). The main immunogenic region is likely on the IQ motif of NRIP. We also showed the IgG subclass of anti‐NRIP autoantibody mainly to be IgG1. Conclusions NRIP is a novel AChRα binding protein and involves structural NMJ formation, which acts as a scaffold to stabilize AChR–rapsyn–ACTN2 complexes. Anti‐NRIP autoantibody is a novel autoantibody in MG and plays a detrimental role in MG with the coexistence of anti‐AChR autoantibody.
BackgroundAlthough the pros and cons of prone and decubitus positioning methods, for posterior approaches to acetabular fractures, have been widely discussed, it remains inconclusive whether a particular patient position is superior to the other. Here we present our preliminary experience with placing the patient in the semiprone position for posterior approaches to the acetabulum as a potentially advantageous alternative.MethodsTechnical notes were provided as well as the preoperative, intraoperative and postoperative images of the demonstrative cases. From July 2018 to April 2020, eight selected patients with complex acetabular fractures were surgically treated through posterior approaches in semiprone position. Patient demographics, fracture pattern, poor prognostic factors and associated conditions were recorded. The quality of fracture reduction was assessed by Modified Matta’s criteria. The operative hip’s function was evaluated by the Modified Merle d’Aubigné-Postel score if follow-up was more than 3 months.Result:The Median age of our cohort was 48.55 years (24.3–70.6). The median body mass index was 23.90 kg/ m2 (17.6–26.4). Satisfactory reduction was achieved in 6 of the 8 patients. Intraoperative radiographs obtained by the standard vertical and horizontal projection of the C-arm machine resembled the classic Judet views. Trochanteric flip osteotomy and surgical hip dislocation were feasible. One hip was converted to total hip replacement 5 months after primary fracture surgery due to femoral head osteonecrosis.Conclusion:The preliminary radiographic and reduction quality of our cohort were comparable to those reported in the literature. The advantages of semiprone position include intuitive intraoperative radiographic acquisition, making gravity as a aid for reduction and feasibility of surgical hip dislocation. Long-term follow-up and further case-controlled or randomized controlled studies are necessary to uphold its value.
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