As an extremely rare malignant neoplasm, only 12 mesenchymal chondrosarcoma (MC) arising in kidney have been reported to date. Herein, we reported a case of primary renal MC resected with robot assistance, which has not been reported before. According to the cases reported in English literature, we analyzed the characteristics of this rare malignancy and systematically review its treatment.

Chondrosarcoma (CS) is a malignant tumour of long and flat bone characterised by the formation of cartilage. Mesenchymal chondrosarcoma (MCS) is a rare subtype of CS that is more aggressive and may lead to erroneous diagnosis in a limited biopsy. The diagnosis is mainly based on the histopathological appearance of biphasic pattern of undifferentiated small round cells separated by islands of well-differentiated hyaline cartilage. We report a case of 13-year-old boy who initially presented with gum swelling and the biopsy result suggested a benign fibrous lesion. Following an extensive lesion shown in radiologic findings, the tumour excision was done and finally was diagnosed as an MCS of the maxilla. The patient was given postoperative chemotherapy (EURO-EWING 99 regimen), and now on regular follow-up for monitoring of local recurrence or tumour metastasis.

Dedifferentiated chondrosarcoma is an aggressive mesenchymal tumor of the bone, and novel therapies are needed to improve its clinical outcomes. Patient-derived cell lines are essential tools for elucidating disease mechanisms associated with poor prognosis and for developing therapies. However, few lines and xenografts have been previously reported in dedifferentiated chondrosarcoma. We established a novel patient-derived dedifferentiated chondrosarcoma cell line, NCC-dCS1-C1. Primary dedifferentiated chondrosarcoma tissues were obtained at the time of surgery and subjected to primary tissue culture. The cell line was established and authenticated by assessing DNA microsatellite short tandem repeats. The cells maintained in monolayer cultures exhibited constant growth, spheroid formation capacity, and invasion ability. When the cells were implanted into mice, they exhibited histological features similar to those of the original tumor. Genomic analysis of single nucleotide polymorphisms showed aberrant genomic contents. The DNA sequencing revealed the absence of IDH1/2 mutations. The global targeted sequencing revealed that the cell line preserved homozygous deletion of CDKN2A and CREBBP. A proteomic study by mass spectrometry unveiled similar but distinct molecular backgrounds in the original tumor and the established cell line, suggesting that tumor cell functions might be altered during the establishment of the cell line. Using a screening approach, four anti-cancer drugs with anti-proliferative effects at a low concentration were identified. In conclusion, a novel dedifferentiated chondrosarcoma cell line, NCC-dCS1-C1, was successfully established from primary tumor tissues. The NCC-dCS1-C1 cell line will be a useful tool for investigations of the mechanisms underlying dedifferentiated chondrosarcomas.

The mesenchymal chondrosarcoma (MC) is a rare malignant tumour and accounts for less than 3% of primary chondrosarcomas. Mostly MC arises from the craniofacial bones, the ribs, the ilium, the femur and the vertebrae. A 54-year-old man was treated due to an icterus of unknown origin. The medical history of the patient consists of a multimodal treated MC of the thoracic vertebrae. A CT imaging identified a 2×4 cm sized mass of the pancreatic head. Suspecting a pancreatic head carcinoma surgical removal was performed. Histopathological a metastasis of MC was diagnosed. Our patient left the hospital after 17 days and died 23 month after surgery. Metastases of MC to the pancreas are rare. When detecting a mass of the pancreas in patients with a medical history of an MC, a metastasis of these tumour should be taken in consideration.

OBJECTIVE: To report differences in clinical features and outcomes between intracranial mesenchymal chondrosarcoma (MCS) and conventional chondrosarcoma (CCS).
METHODS: Clinical data of patients with primary intracranial MCS and CCS were retrospectively extracted and analyzed to compare differences between MCS and CCS.
RESULTS: Seventy-four patients with intracranial chondrosarcoma (61 cases with MCS and 13 cases with CCS) were included. Compared with patients with CCS, patients with MCS presented at a younger mean age (21.1 years vs. 34.5 years, P < 0.001) and had a poor mean preoperative Karnofsky performance scale score (64.6 vs. 77.8, P = 0.014). Compared with CCS, MCS was less often located in the skull base (38.5% vs. 96.7%, P < 0.001) and had a larger tumor volume (87.8 cm
CONCLUSIONS: Clinical features of MCS are quite different from CCS. Treatment strategies used for CCS do not yield satisfactory outcomes for MCS. Treatment of MCS should be aggressive and individualized.

Extraskeletal mesenchymal chondrosarcoma is a rare soft tissue sarcoma arising from soft tissues, mainly of the lower extremities, meninges, and orbits. It usually presents during the second to third decades of life, and has a slight predominance in females. Histologically, it has a typical biphasic pattern comprising small cells and islands of hyaline cartilage. It can pose a diagnostic challenge in small biopsy specimens where 1 of the 2 components can be absent. The prognosis is extremely variable; survival varies depending on the location of the tumor.

OBJECTIVE:: Mesenchymal chondrosarcoma (MCS) of the orbit is a rare and aggressive form of chondrosarcoma. The purpose of this study was to retrospectively identify the imaging features of mesenchymal chondrosarcoma of the orbit.
METHODS:: This study included five patients with histologically confirmed MCS of the orbit who had undergone either CT, MRI, or both. Images were evaluated for the following: location, size, margin, CT density and presence or absence of calcification and/or ossification, MRI findings including dynamic contrast-enhancement and time-intensity curves.
RESULTS:: CT was performed in four of the five patients, and all four (100%) demonstrated calcification and ossification of the mass. MRI was performed in all five patients. In two patients (40%), the mass demonstrated areas of hyperintensity on T
CONCLUSION:: The presence of a well-defined, orbital mass with calcification and ossification on CT and, marked heterogenous enhancement and a rapid-washout pattern on dynamic MRI indicate a high probability of MCS of the orbit. In addition, MCS of the orbit can demonstrate areas of hyperintensity on T
ADVANCES IN KNOWLEDGE:: MCS of the orbit is a highly malignant tumor, and early diagnosis by imaging is important. Radiologists should be aware of the imaging features of MCS of the orbit.

Chondrosarcoma is a rare malignant tumor originating from cartilaginous tissue with a tendency to localize in the epiphysis of long and pelvic bones. Only 7% of all chondrosarcomas originate in the craniocervical region. Metastasis from intracranial chondrosarcoma is extremely rare with only two previously reported cases. We report on a young patient with intracranial chondrosarcoma who presented with extracranial metastasis 2 years after surgical excision of the primary lesion. Gross total excision combined with radiotherapy so far has led to a favorable outcome.

Primary mesenchymal chondrosarcoma of the kidney is extremely rare, with only nine cases reported in the English literature. We report a new case of this disease. A 35-year-old man, presented with flank pain, episodic gross hematuria and a painless palpable mass in left abdominal quadrant. Computed tomography scan identified a left renal tumor with 20 cm, with no evidence of regional or metastatic spread disease. The patient underwent radical nephrectomy. The immunohistopathological diagnosis was mesenchymal chondrosarcoma of the kidney. At 18 months of follow-up, there was no evidence of recurrence or distant metastasis. Primary renal chondrosarcoma is so rare that its prognosis is unknown. Disease recurrence is unpredictable and when it is detected, the prognosis is poor. The radical nephrectomy with complete resection of the tumor with wide resection free margins is recommended, and the patients need long-term and close surveillance, with particular attention to local recurrence and uncommon sites of metastization.

Mesenchymal chondrosarcoma (MCS) is a rare tumor in the orbit. Although optic nerve displacement is a common finding in intraorbital MCS, optic nerve tissue involvement in tumor has rarely been reported in huge tumors associated with intracranial extension. Herein the authors report a patient with MCS involving optic nerve tissue without intracranial extension. A 59-year-old woman with a 2-month history of progressive proptosis and normal vision presented to us. Computed tomography revealed a clearly outlined heterogeneous mass with calcified foci in its center, which was attached to the optic nerve, magnetic resonance imaging showed the mass to be isointense to gray matter on T1- and T2-weighted images. She underwent lateral orbitotomy and partial tumor excision. Histopathologic study confirmed MCS. She refused exenteration till 1 year but the tumor recurred and her vision decreased to no light perception. Then exenteration was performed with obtaining free margin and she is now free of tumor after 6 months without radiotherapy or chemotherapy. Mesenchymal chondrosarcoma must be differentiated from more common calcified tumors attached to optic nerve like meningioma.

OBJECTIVES: Limited data regarding intracranial mesenchymal chondrosarcoma (MCS) are available. The goal of this study was to report the clinical characteristics, challenges in management, and poor outcomes of intracranial MCS.
METHODS: Clinical data for 16 patients with MCS were reviewed retrospectively to evaluate their clinical characteristics, management, and outcomes.
RESULTS: This study included 11 male and 5 female patients with a mean age of 22.9 ± 14.4 years. The most common presentations were headache (n = 10; 62.5%), followed by cranial deficits (n = 7; 43.6%). The radiologic spectrum for MCS was broad, and only 18.8% (3/16) of MCSs were correctly diagnosed preoperatively. Aggressive resection (including subtotal resection and gross total resection) and partial resection was performed in 62.5% (10/16) and 37.50% (6/16) of patients. With a median follow-up of 34 months (range, 10-78 months), 5 patients (31.3%) died and 8 patients (50%) developed tumor recurrence. The 1-, 3-, and 5-year rates of progression-free survival and overall survival were 86%, 53%, and 42% and 93%, 70%, and 56%, respectively. Although the differences were not significantly different, aggressive resection and the use of radiotherapy tended to improve the prognosis of the patients.
CONCLUSIONS: Clinical characteristics of MCS are variable. The current management of intracranial MCS referring to conventional chondrosarcoma could not yield satisfactory outcomes. Further study is needed to identify the optimal treatments.

Mesenchymal chondrosarcoma is a rare but deadly form of chondrosarcoma that typically affects adolescents and young adults. While curative intent is possible for patients with localized disease, few options exist for patients in the unresectable/metastatic setting. Thus, it is imperative to understand the fusion-driven biology of this rare malignant neoplasm so as to lead to the future development of better therapeutics for this disease. This manuscript will briefly review the clinical and pathologic features of mesenchymal chondrosarcoma followed by an appraisal of existing data linked to the fusions, HEY1-NCOA2 and IRF2BP2-CDX1, and the associated downstream pathways.

The diagnosis of mesenchymal chondrosarcoma, a distinctive biphasic malignant neoplasm harboring the HEY1-NCOA2 gene fusion and consisting of primitive round to spindled cells admixed with foci of relatively mature hyaline cartilage, is usually straightforward by morphologic evaluation alone. However, in the setting of a limited biopsy, specimens lacking cartilage generate a broad differential diagnosis, encompassing a variety of other primitive sarcomas, including spindle cell/sclerosing rhabdomyosarcoma. Although a small number of cases of mesenchymal chondrosarcoma with aberrant skeletal muscle marker expression have been reported, pathologists are largely unaware of this potential diagnostic pitfall. We report 6 additional cases of mesenchymal chondrosarcoma showing expression of multiple skeletal muscle markers, including one case initially misdiagnosed as "spindle cell/sclerosing rhabdomyosarcoma" on needle biopsy. Awareness of this phenomenon and judicious application of molecular diagnostic testing for the HEY1-NCOA2 fusion are critical to avoid misclassification of mesenchymal chondrosarcoma as rhabdomyosarcoma, with potentially adverse patient impact.

A 23-year-old woman presented with right-sided painless proptosis that developed in 12 months. MRI studies demonstrated a well-delineated tumorous enlargement of the right lacrimal gland with homogenous signal intensity and compressing the globe. The tumor was removed totally and in 1 piece with the tentative diagnosis of a pleomorphic adenoma. Pathologic examination revealed biphasic neoplastic elements, which were composed of the cartilaginous matrix and small round cell component. Immunohistopathological examination showed positive CD99 staining and negative reaction to S100, panCK, and CD15. The patient then received a total of 64 Gy orbital radiotherapy in 32 fractionations. There has been no recurrence or metastasis during 14 months of follow up. This case showed that mesenchymal chondrosarcoma may arise from the lacrimal gland and must be considered in the differential diagnosis of lacrimal gland tumors in young adults.

[No Abstract Available].

Mesenchymal chondrosarcoma of the orbit is an extremely rare and aggressive tumor. We report image findings of F-fluorodeoxyglucose (FDG) positron emission/computed tomography (PET/CT) in 2 cases, one primary case and one recurrent case. The F-FDG PET/CT images revealed high uptake with an SUVmax of 6.7 and 11.7, respectively. In both cases, the HEY1-CoA2 gene fusion was positive. The high uptake of F-FDG in mesenchymal chondrosarcoma of the orbit well suggests the malignancy of this tumor.

PURPOSE: Mesenchymal chondrosarcoma (MCS) is an aggressive variant of chondrosarcoma and is a rare tumor, particularly within the pediatric population. Commonly, MCS originates in the bone, but it can also arise in extraskeletal sites, such as the brain and the intraspinal area. Due to the rarity of this tumor, there are no guidelines for its optimal treatment.
METHODS: We report a case of intradural extramedullary MCS, located at the T11-T12 level, in a 14-year-old male. The tumor was documented by magnetic resonance imaging and treated with gross total resection (GTR) without adjuvant treatment. We further reviewed the relevant pediatric literature and discussed the management and outcome of intracranial and intraspinal MCS.
RESULTS: The patient's follow-up showed no evidence of disease 2 years from diagnosis. A total of 51 cases of intracranial and intraspinal MCS have been reported (24 intraspinal and 27 intracranial). Recurrence has been described in only 4 patients with intraspinal MSC, and among them 3 received adjuvant chemotherapy and radiotherapy. GTR seems to reduce the risk of recurrence and, due to a higher cancer-mortality rate for these patients, adjuvant chemotherapy and radiotherapy are recommended in case aggressive surgery is not possible.
CONCLUSIONS: According to our single experience, we would suggest that adjuvant therapy might be unnecessary in cases where a localized MCS undergoes GTR. Chemotherapy and radiotherapy should be recommended when GTR cannot be obtained. Further studies are needed to investigate a standard treatment approach for this rare tumor.

BACKGROUND: This study aimed to elucidate the clinical features and prognostic factors of mesenchymal chondrosarcoma (MCS) and investigate optimal treatment strategies.
METHODS: Data from 57 patients with MCS were collected from a Japanese Musculoskeletal Oncology Group (JMOG) and retrospectively analyzed.
RESULTS: Data from 29 males and 28 females were collected. Primary tumor sites were the head and neck (7 patients), trunk (35 patients), and extremities (15 patients). The tumors originating in the trunk were significantly associated with a worse OS compared with those originating at the other sites in all patients and those with localized disease (P = 0.020 and P = 0.019, respectively). In patients with localized disease, the tumors originating in the head and neck were significantly associated with better OS and MFS compared with those originating in the trunk (P = 0.024 and P = 0.014, respectively). Positive surgical margin was significantly correlated with the worse LRFS (P = 0.018). Adjuvant chemotherapy exhibited a clear trend toward improved OS when MCS was localized in the trunk or extremities (P = 0.057).
CONCLUSIONS: Adequate surgery is considered to be the mainstay of treatment for localized MCS. Prognosis was different depending on the site of tumor origin.

The iliac vein is an extremely rare site for mesenchymal chondrosarcoma, and patients with primary extraskeletal mesenchymal chondrosarcoma arising from a vein always suffer a very poor prognosis. We report a case of a 45-year-old female who presented with a 5-month history of left leg edema in 2015. Contrast-enhanced computed tomography showed a large mass in the left iliac vein with scattered calcifications. Wide-margin resection was performed, and histopathologic and immunohistochemical analyses confirmed the presence of intraluminal mesenchymal chondrosarcoma with local invasion out of the vein wall. Due to poor patient compliance, postoperative neoadjuvant chemotherapy and radiotherapy were not started, and a bone scan performed 16 weeks postoperatively showed multiple bone metastases. The patient died on the twenty-fourth postoperative week.

Mesenchymal chondrosarcoma is a rare orbital tumor. Several case reports of this rare tumor have been published in the literature but only 6 cases have documented a follow up of 5 years or more. We report a case of 28 year-old female who presented with left orbital mass. Computed Tomography (CT) revealed a lobulated mass in the superior extraconal space with dense intralesional calcification. Patient underwent complete resection of the mass and histopathology was suggestive of mesenchymal chondrosarcoma. He was given adjuvant radiotherapy and there was no recurrence or metastasis at 5 years of follow-up. The case highlights that a complete resection with adjuvant radiotherapy in cases of orbital mesenchymal chondrosarcoma offers excellent prognosis.

Mesenchymal chondrosarcoma (MC) is a rare malignant neoplasm bearing characteristic dimorphic pattern histologically. We describe two rare cases of primary MC involving two different visceral organs (1) a 24-year-old man with solid renal mass and, (2) a 42-year-old man with cystic splenic mass. The histological and immunophenotypical features of both lesions were classical of MC. Although this lesion is uncommon in visceral organs, the possibility of this rare entity must be kept in differential diagnosis with compatible morphology.

Mesenchymal chondrosarcoma of bone is a rare high-grade variant of chondrosarcoma, which typically has central intramedullary location. The tumor is characterized by admixture of highly anaplastic small round malignant cells and islands of mineralized low-grade hyaline cartilage. It is most unusual for this tumor to arise on the surface of a long bone. We describe a patient with periosteal mesenchymal chondrosarcoma that arose at the surface of the right tibia with multifocal bone metastases. Radiographic, CT, MRI, and PET-CT features of this unusual tumor are presented.

Extraskeletal orbital mesenchymal chondrosarcoma (MC) is an extremely rare and highly aggressive tumour. It has characteristic radiological features and pathognomic histological biphasic pattern. Radical resection with negative margins is the mainstay of treatment; role of adjuvant chemotherapy and radiotherapy is yet not well defined. We report a rare case of 18-year-old man who was diagnosed to have orbital MC. He presented with locally advanced disease with no vision in the affected eye. He underwent right orbital exenteration; a transcranial intradural approach was used to divide the optic nerve, and the temporalis muscle flap was utilised to fill the exenterated orbit. Though optic nerve involvement is rare in orbital MCs, a transcranial approach may be used effectively to avoid traction on optic chiasma and ensure margin-free resection in case of optic nerve involvement up to orbital apex. Unfortunately, prognosis remains dismal in MCs despite treatment.

Cancer is frequently seen in women of reproductive age. Diagnosis, management of treatment, and safety of the therapeutic approach are particularly important for these patients. Presently described is pain management in a case of pregnancy with malignant mesenchymal tumor. A 23-year-old woman in 30th gestational week presented with severe pain in right hip and back of the right thigh. Piriformis block successfully decreased pain and was followed by pulsed radiofrequency (PRF) to the piriformis muscle. PRF, as a non-neurodestructive method, is a safe and effective method to treat cancer pain in a pregnant patient.

BACKGROUND: Chondrosarcomas are very rare malignant, slow-growing tumors that develop in or near the petroclival region of the brain. We report a very rare case in which the tumor originated from left petrous bone and induced intraventricular hemorrhage leading to an acute comatose presentation.
CASE DESCRIPTION: A 28-year-old man initially presented to the outpatient department with a 1-month history of headache, vomiting, vertigo, and left facial numbness. A lesion at the cerebellopontine angle with extension into the middle cranial fossa was demonstrated on computed tomography and magnetic resonance imaging. The following night his condition worsened, and he presented to the emergency department with intraventricular hemorrhage with hydrocephalus. An external ventricular drain was placed in the emergency department to relieve hydrocephalus, and definitive surgical resection of the tumor was subsequently. Postoperatively, his Glasgow Coma Scale score improved, and he was transferred to the surgical intensive care unit where he remained for 3 days. He was subsequently stepped down to a special care unit and then to a ward room. The patient is currently awake and has grade II facial palsy (House-Brackmann), demonstrates spontaneous purposeful eye opening, inconsistently obeys single-step orders, demonstrates no meaningful phonation or vocalization, and has at least grade 4 power in all 4 extremities. He is currently fed through a nasogastric tube and is in rehabilitation.
CONCLUSIONS: Our experience of petroclival junction chondrosarcoma causing intraventricular hemorrhage may be the first to be documented. Preferred treatment of this highly malignant lesion is radical removal with postoperative radiotherapy.

INTRODUCTION: We report the outcome of 23 patients with mesenchymal chondrosarcomas treated with surgery and radiation therapy +/- chemotherapy. The intent of the project was to review the impact of patient and treatment variables on treatment outcome, in particular with regard to extent of surgery and radiation dose.
PATIENTS AND METHODS: Twenty-three patients with mesenchymal chondrosarcomas were treated with surgery and radiation therapy (min. dose 44 Gy; max. dose 78 Gy; median dose 60 Gy; mean dose 61 Gy).
RESULTS: The median survival for the entire cohort of patients was 21.65 years (95% confidence interval ± 4.25). The 5- and 10-year OS was 78.6%. Median disease-free survival for the 23 patients was 7.2 years. Disease-free survival (DFS) at 3 and 5 years was 70.7% and 57.8%, respectively. The local control rate at 5 and 10 years was 89.5% (95%CI 64.1-97.3%). Only three patients experienced local failure, three patients had regional failure, and eight developed distant metastases.
CONCLUSIONS: In this cohort of patients local tumor control was high when using a combination of surgery and radiation. There was not a clear relationship between radiation dose and local tumor control. J. Surg. Oncol. 2016;114:982-986. © 2016 Wiley Periodicals, Inc.

Mesenchymal chondrosarcomas are rare and highly aggressive sarcomas occurring in bone and soft tissue, with poor overall survival. Bcl-2 expression was previously shown to be upregulated in mesenchymal chondrosarcomas. We here report on a newly derived mesenchymal chondrosarcoma cell line, MCS170, in which we investigated treatment with the BH3 mimetic ABT-737 alone or in combination with conventional chemotherapy as a possible new therapeutic strategy. The presence of the characteristic HEY1-NCOA2 fusion was confirmed in the MCS170 cell line using FISH, RT-PCR, and sequencing. The MCS170 cell line was treated with ABT-737 alone or in combination with doxorubicin or cisplatin. Cell viability and proliferation was determined using WST-1 viability assays and the xCELLigence system. Expression of Bcl-2 family members was studied using immunohistochemistry. Apoptosis was determined using the caspase-glo 3/7 assay and western blot for PARP cleavage. The MCS170 cell line was sensitive to doxorubicin treatment with an IC50 of 0.09 μM after 72 h, but more resistant to cisplatin treatment with an IC50 of 4.5 μM after 72 h. Cells showed little sensitivity toward ABT-737 with an IC50 of 1.8 μM after 72 h. Combination treatments demonstrated ABT-737 synergism with cisplatin as well as doxorubicin as shown by induction of apoptosis and reduction in cell proliferation. Restoration of the apoptotic machinery by inhibition of Bcl-2 family members sensitizes MCS170 mesenchymal chondrosarcoma cells to conventional chemotherapy. This indicates that combining the inhibition of Bcl-2 family members with conventional chemotherapy can be a possible therapeutic strategy for patients with mesenchymal chondrosarcoma.

BACKGROUND: Intracranial extraskeletal mesenchymal chondrosarcomas (MCSs) are rare tumors accounting for <0.16% of intracranial tumors. They are usually described as occurring in the age group of 20-30 years and are commonly found in the frontoparietal region arising from the falx and surrounding dura. We describe 3 cases at varying ages, locations, and outcomes.
CASE DESCRIPTION: A 42-year-old woman with anterior one third falx-based lesion; a 7-year-old boy with mid one third falcine lesion with hyperostosis of bone, presenting in comatose stage; and a 52-year-old woman with left posterior lateral frontal dural-based lesion are presented. Histopathology of all cases was confirmed with immunohistochemistry. All patients underwent complete excision but had varying outcomes.
CONCLUSIONS: Intracranial MCSs are rare malignant tumors with poor prognosis. Because of their rarity, it may not be considered as a differential diagnosis and it is often misdiagnosed radiologically, but the importance lies in the need of radical excision. The potential effect of postoperative radiotherapy and chemotherapy is controversial. This article sheds some light on variable prognosis of this tumor.

Mesenchymal chondrosarcoma (MC) is an aggressive small, round, blue cell tumor with chondrogenic differentiation that typically arises in bony sites. Approximately, a third of these tumors develop in extraskeletal sites such as the meninges, and somatic soft tissue. The MCs are well-circumscribed, lobulated masses, with focal calcification. Histologically, 2 distinct populations of neoplastic cells characterize MC: sheets of primitive small, round, blue cells surrounding islands of well-developed hyaline cartilage with mature chondrocytes in lacunae. Involvement of the gastrointestinal tract and pancreas by primary or metastatic MC is a relatively rare occurrence. We identified 8 patients with MC in our departmental archives from 1990 to 2015, two of which had pancreatic involvement. The patients were young women who developed masses in the distal pancreas. Molecular testing demonstrated that both tumors harbored the recently described HEY1-NCOA2 gene fusion. These cases illustrate that pancreatic involvement can occur in MC, and the demonstration of HEY1-NCOA2 fusion can be helpful to confirm the diagnosis.

BACKGROUND: Mesenchymal chondrosarcoma is a rare malignant tumor arising from bone or soft tissues. Instraspinal dumbbell-shaped mesenchymal chondrosarcoma is even rarer; however, it should not be neglected by clinicians.
CASE PRESENTATION: A 26-year-old female was referred to our hospital with a 1.5-month history of sciatic pain and numbness in the left leg. Computed tomography and magnetic resonance imaging scans revealed an intraspinal dumbbell-shaped mass which had distinguishing features of neurogenic tumors, surprisingly, with massive calcifications, and no tumor metastasis was found. Then the patient underwent a total resection of the tumor, and during the operation, we found that the right nerve root of the fifth lumbar almost disappeared. The tumor was diagnosed as mesenchymal chondrosarcoma by histopathological examination after operation. Adjuvant therapies were not performed. However, recurrence of the tumor occurred 5 months later, and she underwent a total resection again combined with radiotherapy after second surgery.
CONCLUSIONS: To the best of our knowledge, this case study presents the first report in literature about primary instraspinal dumbbell-shaped mesenchymal chondrosarcoma with massive calcifications, which may provide some evidence for clinical practice. As the clinical symptoms and radiographic findings of mesenchymal chondrosarcoma are usually not specific, clinicians should consider it as a possible case and diagnose it through careful histopathological examination. Sometimes, calcification could be seen in tumors, which may influence or reflect the growth of tumor and disease prognosis. Although prognosis in mesenchymal chondrosarcoma varies from person to person, generally, complete resection, adjuvant therapy, and regular examinations are recommended to perform for patients with mesenchymal chondrosarcoma.