Extraskeletal Myxoid Chondrosarcoma of the Jugular Foramen in a Pediatric Patient: A Case Report and Comprehensive Review of the Literature

Introduction: Extraskeletal myxoid chondrosarcoma of the jugular foramen is a rare clinical entity, especially in the pediatric population. Thus, it can be confused with other pathologies. Case Presentation: We report an extremely rare case of a 14-year-old female patient with jugular foramen myxoid chondrosarcoma that was completely removed through microsurgical resection. Conclusion: The primary purpose of the treatment is gross total resection of the chondrosarcomas. However, adjuvant methods such as radiotherapy should additionally be applied in patients who have high-grade diseases or cannot undergo gross total resection because of anatomic localization.


Introduction
Chondrosarcomas are malignancies that usually occur in the central part of large bones, such as the femur, pelvis, humerus, scapula, and ribs [1,2]. They constitute karger@karger.com www.karger.com/pne approximately 11% of all malignant primary bone tumors [1,3]. Intracranial involvement of chondrosarcomas is rare and accounts for 0.15% of all intracranial tumors and 6% of all skull base tumors [3][4][5]. Intracranial chondrosarcomas are usually located at the anterior skull base, maxillary sinus, ethmoid sinus, sella turcica, and nasal cavity [2,3,5]. The Chondrosarcomas are more frequent in the fifth and sixth decades of life but not in the pediatric population. Herein, we report a case of a 14-year-old female patient with extraskeletal myxoid chondrosarcoma of the jugular foramen and discuss the relevant literature.

Case Presentation
A 14-year-old girl was admitted to our clinic with complaints of dysphonia, dysphagia, tinnitus, and diplopia for 2 months. She had no contributive medical history. She was conscious, and her pupils were equal and reactive to light. Involvement of left-sided abducens and lower cranial nerves was noted. She showed impaired gag reflex on the left side, deviation of the uvula to the right side, and left shoulder and sternocleidomastoid muscle weakness revealing Vernet's (jugular foramen) syndrome.
Brain magnetic resonance imaging (MRI) revealed a mass lesion measuring 28 × 30 × 27 mm at the left-sided cerebellopontine angle cistern and jugular foramen (Fig. 1). The mass was hypointense on T1-weighted images and hyperintense on T2weighted images and showed heterogeneous contrast enhancement with gadolinium administration (Fig. 1). Compression on the brainstem and cerebellar peduncle was noted.
Tumor resection was planned for relieving brainstem and cranial nerve compression as well as for histopathologic sampling. Gross total resection (GTR) of the tumor was performed via left-sided retrosigmoid approach. The tumoral portion in the jugular foramen was also resected. Bone destruction and enlargement of the left-sided jugular foramen were detected on postoperative brain computed tomography ( Fig. 2a-c). Histopathological examination of the samples revealed myxoid, chondroid tumor cells with eosinophilic cytoplasms, and nodular growth pattern ( Fig. 3a-c). Immunohistochemical staining was negative for brachyury and keratin (Fig. 3d, e). However, S100 protein was positive (Fig. 3f), and the tumor was diagnosed as extraskeletal myxoid chondrosarcoma.
The postoperative course of the patient was uneventful, and her complaints improved. In the third month after surgery, contrastenhanced brain MRI did not reveal any residual or recurrent lesion ( Fig. 2d-f). Moreover, she presented no recurrence or new complaints at the 15-month follow-up.
Establishing the differential diagnosis of jugular foramen tumors is quite challenging. Primary tumors, including glomus jugular tumors, schwannomas, meningiomas, peripheral primitive neuroectodermal tumors, and secondary tumors including chordomas, chondrosarcomas, chondroblastomas, giant cell tumors, temporal bone metastases, can invade the jugular foramen [11,12]. Chondrosarcomas are extradural or intradural, laterally located lesions frequently associated with erosive and destructive bone changes, entrapped bony trabeculae, areas of necrosis, and recent or old hemorrhages on radiological scans [12,13]. Brain computed tomography scans reveal bone destruction and tumor calcifications. Chondrosarcomas are hypointense on T1-weighted images and hyperintense on T2-weighted images and show heterogeneous contrast enhancement with gadolinium on brain MRI [5,10,12].
The primary objective in the treatment of intracranial chondrosarcomas is GTR of the tumor [2,5,9,14]. However, total resection is not always possible because of their proximity to cranial nerves, important vascular structures, and eloquent brain areas such as the brainstem [1,4]. Adjuvant treatments including fractionated radiotherapy, stereotactic radiosurgery, or proton beam radiotherapy should be administered to patients with high-grade diseases or in whom total tumor resection cannot be achieved [3-5, 10, 11, 14, 15]. The application of chemotherapy is a controversial topic, and no widely accepted chemotherapy regimen for these tumors has been reported in the literature [5,10,15].
According to our literature review, chondrosarcomas of the jugular foramen are rare tumors, especially the myxoid subtype. Moreover, only 11 cases of jugular foramen chondrosarcomas have been reported so far ( Table 1). The present case is the second case of the myxoid subtype and the second in the pediatric population. However, to the best of our knowledge, she is the first pediatric patient with a myxoid chondrosarcoma of the jugular foramen (Table 1).

Conclusion
Extraskeletal myxoid chondrosarcomas of the jugular foramen are rare tumors, especially in the pediatric population. Because of their slow-growing nature and tendency for local recurrence, GTR of the tumors should be the aim of the treatment. However, adjuvant methods such as radiotherapy should be additionally applied in patients with high-grade diseases or those in whom total tumor resection cannot be achieved.