Primary spinal intradural mesenchymal chondrosarcoma with detection of fusion gene HEY1-NCOA2: A paediatric case report and review of the literature

Mesenchymal chondrosarcoma is an extremely rare malignant tumour that most commonly originates in the bone, but is also present in extraskeletal sites. The tumour is morphologically characterized by a biphasic pattern of small round cells and islands of cartilage. Spinal mesenchymal chondrosarcomas are even rarer and, therefore, few investigations exist regarding the biological behaviour of the tumours. In the present study, we report a case of a 10-year-old female presenting with 9 months of back pain and radiographic findings of an intradural lesion measuring 1.5 cm at the level of Th4. The tumour was completely excised and subjected to pathological analyses. Following detection of the HEY1-NCOA2 fusion gene, the tumour was morphologically and immunohistochemically defined as an intradural mesenchymal chondrosarcoma attached to the dura mater. In this study, we validate the recent identification of the fusion gene HEY1-NCOA2 in paediatric extraskeletal mesenchymal chondrosarcomas. The relevant literature is reviewed and further discussed in relation to our findings.

Chromosome aberrations and HEY1-NCOA2 fusion gene in a mesenchymal chondrosarcoma

Mesenchymal chondrosarcomas are fast-growing tumors that account for 2-10% of primary chondrosarcomas. Cytogenetic information is restricted to 12 cases that did not show a specific aberration pattern. Recently, two fusion genes were described in mesenchymal chondrosarcomas: a recurrent HEY1-NCOA2 found in tumors that had not been cytogenetically characterized and an IRF2BP2-CDX1 found in a tumor carrying a t(1;5)(q42;q32) translocation as the sole chromosomal abnormality. Here, we present the cytogenetic and molecular genetic analysis of a mesenchymal chondrosarcoma in which the patient had two histologically indistinguishable tumor lesions, one in the neck and one in the thigh. An abnormal clone with the G-banding karyotype 46,XX,add(6)(q23),add(8)(p23),del(10)(p11),+12,-15[6] was found in the neck tumor whereas a normal karyotype, 46,XX, was found in the tumor of the thigh. RT-PCR and Sanger sequencing showed that exon 4 of HEY1 was fused to exon 13 of NCOA2 in the sample from the thigh lesion; we did not have spare material to perform a similar analysis of the neck tumor. Examining the published karyotypes we observed numerical or structural aberrations of chromosome 8 in the majority of the karyotyped mesenchymal chondrosarcomas. Chromosome 8 was also structurally affected in the present study. The pathogenetic mechanisms behind this nonrandom involvement are unknown, but the presence on 8q of two genes, HEY1 and NCOA2, now known to be involved in mesenchymal chondrosarcoma tumorigenesis is, of course, suggestive.

Radiation therapy is associated with fewer recurrences in mesenchymal chondrosarcoma

BACKGROUND

Mesenchymal chondrosarcoma (MSC) is a rare variant of chondrosarcoma. Because of the rarity of the disease, most studies only contain a small number of patients and thus the prognostic variables and role of adjuvant therapies remain controversial.

QUESTIONS/PURPOSES

We therefore asked (1) what the overall and disease-free survival were for patients with this diagnosis at 5 and 10 years; (2) whether there were significant prognostic factors associated with survival; and (3) whether use of adjuvant chemotherapy or radiotherapy was associated with survival in patients with MSC.

METHODS

We retrospectively reviewed the cases of MSC diagnosed from 1979 to 2010 at one referral center. Forty-three cases were identified. Thirty-seven cases were analyzed for demographics, treatments, and outcomes. Thirty patients with localized disease were analyzed for prognostic factors. The minimum followup was 1 month (mean, 6 years; range, 1 month to 17 years). There were 17 females and 20 males. The mean age at diagnosis was 33 years (range, 11-65 years). Nineteen cases were skeletal and 18 cases were extraskeletal. Seventy-six percent of the tumors were located in the trunk.

RESULTS

Five- and 10-year overall survival was 51% and 37%, respectively. Five- and 10-year disease-free survival was 23% and 5%, respectively. Age (< 30 years) and male sex were associated with poorer overall and disease-free survival in patients presenting with a localized tumor, respectively. Patients who did not receive radiotherapy were more likely to have a local recurrence. Adjuvant chemotherapy failed to show a significant association with overall, disease-free, metastasis-free, or local recurrence-free survival.

CONCLUSIONS

The present study reinforced the role of adjuvant radiotherapy for local tumor control.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Chemotherapy improved prognosis of mesenchymal chondrosarcoma with rare metastasis to the pancreas

Extraskeletal mesenchymal chondrosarcoma is rare and metastasis to the pancreas is extremely rare, with only four cases reported in the literature. The therapeutic effectiveness of chemotherapy remains uncertain. We report a 39-year-old man with extraskeletal mesenchymal chondrosarcoma of the buttock, who had metastases to the pancreas, bones, and lung. He underwent distal pancreatectomy, resection of the buttock tumor, and chemotherapy. He had a good response to chemotherapy and survived for about 3 years after surgery.

Chondrosarcoma of bone

Chondrosarcoma is a cartilage forming neoplasm, which is the second most common primary malignancy of bone. Clinicians who treat chondrosarcoma patients must determine the grade of the tumor, and must ascertain the likelihood of metastasis. Acral lesions are unlikely to metastasize, regardless of grade, whereas axial, or more proximal lesions are much more likely to metastasize than tumors found in the distal extremities with equivalent histology. Chondrosarcoma is resistant to both chemotherapy and radiation, making wide local excision the only treatment. Local recurrence is frequently seen after intralesional excision, thus wide local excision is sometimes employed despite significant morbidity, even in low-grade lesions. Chondrosarcoma is difficult to treat. The surgeon must balance the risk of significant morbidity with the ability to minimize the chance of local recurrence and maximize the likelihood of long-term survival.

Primary extraskeletal mesenchymal chondrosarcoma of the vulva

Extraskeletal chondrosarcoma is rare, making up only 1% of reported chondrosarcoma. We experienced 3 cases of extraskeletal chondrosarcoma, especially in vulva. They were suspected as lipoma of the vulva. The patients had noticed a small but growing mass on their vulva which had been palpated earlier. The masses were excised with a 2 cm resection margin. The final pathological reports confirmed extraskeletal mesenchymal chondrosarcoma (EMC) of the vulva revealing no microscopic lesions on the resection margins. After 24 months of following from the initial diagnosis, the patients remain without evidence of any recurrent. Management of EMC is not well studied due to the rare and variable nature of the disease. However, the surgery, such as we had, is the mainstay of local treatment with studies showing better survival in patients who undergo wide surgical resection. The establishment of adjuvant systemic pharmacotherapy could be expected in the future.

The imaging of cartilaginous bone tumours. II. Chondrosarcoma

Chondrosarcoma is the third most common primary malignant bone tumour. There are various histological subtypes of chondrosarcomas, of which conventional intramedullary chondrosarcoma is by far the most common. Rarer sub-types include clear cell chondrosarcoma, myxoid chondrosarcoma, mesenchymal chondrosarcoma and dedifferentiated chondrosarcoma. Chondrosarcoma is also classified into central, peripheral and periosteal, dependent upon the lesion site, and into primary chondrosarcoma if the lesion arises de novo and secondary chondrosarcoma if the tumour arises in a pre-existing lesion. The various subtypes of chondrosarcoma have characteristic imaging features that may aid diagnosis and may guide biopsy, therefore potentially preventing misdiagnosis. The aim of this article is to provide an overview of the pertinent clinical and imaging findings of the different forms of chondrosarcoma.

Whole-transcriptome sequencing identifies novel IRF2BP2-CDX1 fusion gene brought about by translocation t(1;5)(q42;q32) in mesenchymal chondrosarcoma

Mesenchymal chondrosarcomas (MCs) account for 3–10% of primary chondrosarcomas. The cytogenetic literature includes only ten such tumours with karyotypic information and no specific aberrations have been identified. Using a purely molecular genetic approach a HEY1-NCOA2 fusion gene was recently detected in 10 of 15 investigated MCs. The fusion probably arises through intrachromosomal rearrangement of chromosome arm 8 q. We report a new case of MC showing a t(1;5)(q42;q32) as the sole karyotypic aberration. Through FISH and whole transcriptome sequencing analysis we found a novel fusion between the IRF2BP2 gene and the transcription factor CDX1 gene arising from the translocation. The IRF2BP2-CDX1 has not formerly been described in human neoplasia. In our hospital’s archives three more cases of MC were found, and we examined them looking for the supposedly more common HEY1-NCOA2 fusion, finding it in all three tumours but not in the case showing t(1;5) and IRF2BP2-CDX1 gene fusion. This demonstrates that genetic heterogeneity exists in mesenchymal chondrosarcoma.

Extraskeletal cartilaginous, osseous, and chordoid tumors in children and adolescents

Extraskeletal cartilaginous, osseous, and chordoid tumors are extraordinarily rare in children and adolescents. These lesions are diagnostically challenging due to their rarity and their overlap with metastatic osteosarcoma, reactive or metabolic calcifying and bone-forming masses, various pseudosarcomatous proliferations such as myositis ossificans, and other rare genetic or metabolic disorders. This article reviews the clinicopathologic features and differential diagnosis of extraskeletal cartilaginous, osseous, and chordoid neoplasms in the first two decades of life and highlights the use of diagnostic adjuncts.

[Primary malignant bone tumors]

Among human neoplasms, primary malignant bone tumors are fairly rare. They present an incidence rate of roughly 10 cases per 1 million inhabitants per year. During childhood (<15 years), the percentage of malignant bone tumors amounts to 6% of all infantile malignancies. Only leukemia and lymphoma show a higher incidence in adolescence. Of all primary malignant bone tumors, 60% affect patients younger than 45 years and the peak incidence of all bone tumors occurs between 15 and 19 years. The most common primary malignant bone tumors are osteosarcoma (35%), chondrosarcoma (25%), and Ewing's sarcoma (16%). Less frequently (≤ 5%) occurring tumors are chordoma, malignant fibrous histiocytoma of bone, and fibrosarcoma of bone. Vascular primary malignant tumors of bone and adamantinoma are very rare. Staging of the lesion is essential for systemic therapeutic decision-making and includes complete imaging and histo-pathological confirmation of the suspected entity. In most cases, this is established by open- or image-guided biopsy. Based on this information, an interdisciplinary tumor board will determine the individual therapeutic approach. Endoprosthetic or biological reconstruction following wide tumor resection is the most common surgical therapy for primary malignant bone tumors. There is vital importance in a thorough postoperative follow-up and continous after-care by a competent tumor center which is permanentely in charge of therapy.

Appraising the current role of chemotherapy for the treatment of sarcoma

Sarcomas are a heterogeneous group of relatively rare mesenchymal neoplasms. They can be grouped into two general categories: soft tissue sarcoma (STS) and primary bone sarcoma, which are treated differently. Because sarcomas are relatively rare and complex with a wide variety of different histopathologic subtypes, evaluation by multidisciplinary teams who have expertise in the field is recommended. Treatment guidelines for the use of chemotherapy in patients with STS and bone sarcoma have been published by the National Comprehensive Cancer Network. The role of adjuvant chemotherapy in resected STS remains controversial. Although chemotherapy improves disease-free survival, the long-term overall survival benefit remains unproven. Chemotherapy is typically used as palliative treatment for most subtypes of metastatic STS. In contrast, chemotherapy has a proven role in the treatment of primary bone tumors and Ewing sarcoma, but it has not demonstrated efficacy in the treatment of chondrosarcoma. The standard chemotherapy regimens used in sarcoma are associated with significant toxicity, including long-term complications. Less intense and less toxic regimens are the focus of ongoing clinical research. Newer cytotoxic agents with an improved safety profile, such as trabectedin and palifosfamide, are currently in development. Future research needs to focus on identification of subpopulations of patients that are most likely to benefit from chemotherapy.

Mesenchymal Chondrosarcoma: Clinicopathologic Study of 20 Cases

Context.—Mesenchymal chondrosarcoma is a rare, high-grade malignancy of bone or soft tissue with a unique, biphasic histology and poor prognosis. Because of its rarity and variable length of disease-free survival, the natural history of the disease remains poorly understood.

Objective.—To present clinical, radiographic, and histopathologic features of mesenchymal chondrosarcoma from one of the largest case series collected by a single, senior-level bone pathologist.

Design.—Twenty cases were reviewed in consultations spanning 45 years.

Results.—Eighteen tumors (90%) originated in bone, and 2 tumors (10%) were of extraskeletal origin. Of the skeletal tumors, locations included craniofacial bones (n  =  9; 50%), ribs and chest wall (n  =  4; 22%), sacrum and spinal elements (n  =  3; 17%), and lower extremities (n  =  2; 11%), whereas soft tissue tumors were located about the scapula (n  =  1; 50%) and lower extremity (n  =  1; 50%). Plain radiographs demonstrated calcified, osteolytic lesions with extraosseous extension. Typical histologic features were identified consisting of small, round or spindled cells, interspersed with hyaline cartilage islands. Seventeen patients (85%) were treated surgically, and 8 patients (40%) received adjuvant treatment. Seven patients (35%) were living at last follow-up, 1.8 to 12.5 years after diagnosis, and 8 patients (40%) died between 1.2 and 21.8 years after diagnosis.

Conclusions.—Mesenchymal chondrosarcoma presents multiple challenges. Diagnostic pitfalls include inadequate biopsy samples, which may result in sample error. Sox9 has been proposed as a unique marker for mesenchymal chondrosarcoma which may improve diagnostic specificity. Treatment and prognosis vary considerably. Patients who receive surgery and chemotherapy seem to fare better. Multicenter studies with higher sample numbers may improve our understanding of this malignancy.

Imaging pediatric bone sarcomas

Primary malignant bone tumors are rare and account for about 6% of all new pediatric cancer cases per year in the United States. Identification of the lesion not uncommonly occurs as a result of imaging performed for trauma. Clinical and standard imaging characteristics of the various tumor types are evolving in concert with treatment advancements and clinical trial regimens. This article reviews the 3 most common pediatric bone sarcomas-osteosarcoma, Ewing sarcoma, and chondrosarcoma-and their imaging as applicable to contemporary disease staging and monitoring, and explores the roles of evolving imaging techniques.

UK Guidelines for the Management of Bone Sarcomas

These guidelines have been developed in order to provide an overview and a set of broad-based key recommendations for the management of patients with bone sarcomas in the UK. They have taken into consideration the most up-to-date scientific literature along with the recent recommendations by the European Society of Medical Oncology. The principles of the NICE guidance on both "improving outcomes for patients with sarcomas" and "improving outcomes with children and young people with cancer" have been incorporated. As care evolves, it is acknowledged that these guidelines will need updating. The key recommendations are that bone pain or a palpable mass should always lead to further investigation and patients with clinicoradiological findings suggestive of a primary bone tumour should be sent to a reference centre. Patients should then have their care managed at such a specialist centre by a fully accredited multidisciplinary team.

The clinical management of chondrosarcoma

OPINION STATEMENT

Chondrosarcomas (CHS) represent a heterogeneous group of disorders ranging from indolent, low-grade tumors to aggressive, high-grade forms. Surgical resection represents the primary and preferred treatment modality for individuals with localized disease. Radiation therapy is appropriate for the treatment of positive surgical margins or palliation of disease-related symptoms. The treatment of advanced, metastatic disease is particularly challenging given the recognition that conventional chemotherapy has proven to be largely ineffective. Systemic chemotherapy may be considered in variant forms such as mesenchymal or dedifferentiated chondrosarcomas but high-quality data supporting its use is limited. There is universal agreement, however, that novel treatment strategies are desperately needed. This review will highlight the need for a coordinated multidisciplinary approach to optimize the management and care of patients.