British Journal of Radiology (2004) 77, 1046-1049
© 2004 British Institute of Radiology
doi: 10.1259/bjr/16676268
Extraskeletal Ewing's sarcoma of the parapharyngeal space
S-H Ng, MD1,
S-F Ko, MD1,
Y-C Cheung, MD1,
H-F Wong, MD1 and
S-M Jung, MD2
Departments of 1 Radiology, and 2 Pathology, Chang Gung Medical College and Chang Gung Memorial Hospital, 5 Fu-Shing Street, Kwei Shan, Tao Yuan, Taiwan
Correspondence: Dr Shu-Hang Ng, First Department of Diagnostic Radiology, Chang Gung Memorial Hospital at Linkou, 5-Fu-Shing street, Kwei Shan, TaoYuan, Taiwan
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Abstract
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Extraskeletal Ewing's sarcoma (EES) is rarely found in the head and neck region. We report here a case of EES of the parapharyngeal space in a 53-year-old man who presented with blurred vision, dysphagia, hoarseness and right facial numbness. CT examination showed a large, seemingly well-defined soft tissue mass in the right parapharyngeal space with skull base destruction and intracranial extension. The patient showed poor response to chemotherapy and radiotherapy and died 6 months after initial presentation. A review of the literature revealed no previous reports of EES occurring in the parapharyngeal space.
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Introduction
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Extraskeletal Ewing's sarcoma (EES) is a rare, rapidly growing, round-cell, malignant tumour that can develop in the soft tissues at any location. It was first described by Tefft et al [1] in four patients who presented with paravertebral soft tissue tumours with histological appearance resembling Ewing's sarcoma. In a clinicopathological study of 39 cases of EES reported by Angervall and Enzinger [2], the paravertebral region was the most frequent site of involvement, followed by the lower extremity and chest wall. The head and neck region is an unusual primary site for this tumour and, according to Chao et al [3], there were only five out of 118 cases of EES located in the head and neck region. Herein, we report a case of EES occurring in the parapharyngeal space.
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Case report
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A 53-year-old Chinese man had suffered from blurred vision for more than 6 months. Diplopia, dysphagia, hoarseness and numbness in the right face developed gradually. Physical examination showed a large, non-tender, smooth bulging submucosal mass located in the right pharyngeal region. Nasopharyngeal biopsy was performed and yielded chronic inflammation. Head and neck CT examination showed a seemingly well-defined tumour, measuring about 5 cm x 4 cm, that was located in the right parapharyngeal space and compromised the regional airway (Figure 1
). The tumour exhibited inhomogeneous contrast enhancement with scattered hypodense foci. It displaced the adjacent right internal carotid artery (ICA) anterolaterally with focal arterial encasement. Irregular bony destruction of the right jugular fossa, hypoglossal canal, foramen lacerum and petro-occipital synchondrosis was noted. Apart from the extension of the tumour to the right sphenoid sinus and cavernous sinus, enhanced soft tissue masses were noted along the expected courses of the cisternal portion of the right cranial nerve V, and IX to XII complex, suggesting perineural tumour spread. Since transoral biopsy of the submucosal lesion via an open mouth could not have been performed molar direct visual guidance and required general anaesthesia, the patient was subjected to CT-guided biopsy with a coaxial biopsy system (Temno; Bauer Medical, Clearwater, FL), using an oblique retromaxillary approach. After local anaesthesia was given and a small incision was made, a 17-gauge guiding needle was advanced through the skin towards the target lesion. The guiding needle path was adjusted to the predetermined trajectory using CT guidance until the parapharyngeal lesion was successfully punctured. Through the guiding needle, an 18-gauge spring-loaded automated cutting needle was pushed into the parapharyngeal lesion and its proper position was confirmed by CT (Figure 2). A whitish tissue core was then obtained by triggering the spring-loaded cutting needle. Two more specimens were harvested from the different parts of the parapharyngeal lesion by manually steering the extrafacial portion of the guiding needle. Histopathological examination showed poorly differentiated small blue round cells with oval nuclei and scanty cytoplasm (Figure 3). Immunohistochemical studies showed that the tumour cells stained diffusely with O-13 and were focally positive for S-100 protein, but stained negative for AE1/AE3, HHF-35, neurofilament, chromogranin and common leukocyte antigen. According to the CT findings, histological pattern and the results of the immunohistochemical studies, the final diagnosis was parapharyngeal EES.
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Figure 1. (a) Axial contrast-enhanced CT at the level of the oropharynx shows a large, seemingly well-defined, inhomogeneously enhanced mass in the right parapharyngeal space with multiple small areas of low attenuation inside. Note the compromise of the regional airway and encasement of the adjacent carotid artery. (b) Axial contrast-enhanced CT at the level of the skull base and (c) coronal contrast-enhanced CT show irregular bony destruction of the right jugular fossa and hypoglossal canal, and intracranial invasion with perineural tumour spread. (d) Axial contrast-enhanced CT at the level of the sella shows right cavernous sinus invasion with obliteration of Meckel's cave and retrograde tumour extension to the right prepontine cistern.
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Figure 2. Axial CT image demonstrates the biopsy needle in place in the right parapharyngeal mass via the oblique retromaxillary approach.
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Figure 3. (a) Histopathology shows tumours cells with prominent nuclei but scanty cytoplasm (haematoxylin and eosin: x 132). (b) Immunohistochemical study for O-13 shows strong staining of the tumour cells.
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The patient refused debulking surgery and was treated with chemotherapy (cyclophosphamide, Adriamycin and Vincristine) and radiotherapy. However, the treatment response was poor, and he died 6 months after his initial presentation.
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Discussion
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EES is a rare malignant neoplasm of uncharacterized mesenchymal cell origin. This tumour is equally prevalent in males and females. Young adolescents and adults between the ages of 10 years and 30 years are predominantly affected, however, cases have been documented in patients between 14 months and 63 years of age [2, 4]. Thus, the advanced age of our patient is not unprecedented. EES usually arises in the soft tissues of the trunk, paravertebral region, intercostal area, lower extremities and pelvis [2, 4]. EES in the head and neck regions is uncommon, in which the nose, eyelid, nasopharynx, parotid gland, scalp and cervical region have been described [3, 5–12]. However, no case originating from the parapharyneal space has been reported to date.
Clinically, patients with extremity EES usually present with a painless, rapidly growing mass but tumours arising elsewhere may be painful. Our patient with parapharyngeal EES, however, presented with a large, painless tumour and multiple cranial nerves dysfunction. Although EES tends to spread locally, it usually has a pseudocapsule on gross specimen and thus appears well circumscribed on CT or MR images. Most tumours are of low attenuation or contain areas of lower attenuation than the adjacent muscle on CT and appear hypoechoic on ultrasound scans, reflecting the frequent microscopic findings of tumour necrosis [10, 13]. On MR images, these tumours are generally of low to intermediate signal intensity on T1 weighted images, of high signal intensity on T2 weighted images, and exhibit heterogeneous contrast enhancement [8, 10, 12]. Spontaneous tumour haemorrhage, adjacent bone destruction and regional metastatic adenopathy have been demonstrated in some cases using MRI or CT, but no evidence of tumoral calcification prior to treatment has been reported [3, 6, 7, 10, 13]. In accordance with the previous description, the tumour from our patient appeared to be well circumscribed, inhomogeneous and showed no calcification on CT. Anterior displacement of the ICA and perineural spread along the cranial nerve V and IX to XII complex were well demonstrated. It is worth noting that CT also demonstrated arterial encasement and irregular bone destruction, suggesting a highly aggressive malignant tumour. The differential diagnosis in this case, mainly included salivary gland tumours, neurogenic tumours and paragangliomas. Salivary gland tumours, regardless of whether they arise from the parotid gland, from the salivary rests in the pre-styloid fat, or from the pharyngeal minor salivary glands, are anterior to the ICA and will displace the ICA posteriorly. Neurogenic tumours are usually fusiform enhancing masses that can displace the ICA anteriorly, but they tend to cause smooth remodelling of the skull base rather than irregular bone destruction. Paragangliomas are generally vividly-enhancing masses that displace the ICA anteriorly and can cause irregular, shaggy-appearing bony margins, but they do not show perineural spread along the trigeminal nerve. Other diagnoses to be considered include lymphoma, meningioma, haemangioendothelioma, metastatic disease and other sarcomas.
EES is histologically similar to primary osseous Ewing's sarcoma, and is often confused with other small round cell tumours. Recent advancements in immunohistochemistry aid in the diagnosis of EES. Since the expression of the cell surfaces glycoprotein p30/32 on the EES tumour cells can be recognized by monoclonal antibody O-13, small round cell tumour with strong immunoreactivity for O-13 is highly indicative of EES [3, 11, 14, 15]. Although primitive neuroectodermal tumour, neuroblastoma, embryonal rhabdomyosarcoma and lymphoma may occasionally show positive staining by O-13 antibody [15], their respective diagnosis can be eliminated by negative staining for chromogranin, neurofilament, HHF-35, and common leukocyte antigen [3, 8]. This unusual case of parapharyngeal EES also demonstrated the clinical usefulness of CT-guided core-needle biopsy coupling with detailed immunohistochemical studies in the diagnosis of the deep-seated tumour in the head and neck region.
EES usually follows an aggressive course with a high rate of recurrence. Distant metastases are common, most frequently to the lung. Although the prognosis for this tumour is grave, it is potentially curable [2, 12, 16]. Early, adequate surgical resection followed by adjunctive chemotherapy and radiotherapy has greatly improved the prognosis of EES [4, 10, 16]. Ahmad et al [16] demonstrated that patients treated with surgery, even when the margins were narrow, fared better than those patients who did not undergo tumour resection. They also found that patients with age less than 16 years did significantly better in terms of both disease-free survival and overall 5-year survival. Due to relative inaccessibility of the tumour to surgery and the late-stage presentation of this parapharyngeal EES, our patient chose chemotherapy and radiotherapy. However, this combined treatment was ineffective, and he died shortly after the diagnosis.
Received for publication May 30, 2003.
Revision received April 16, 2004.
Accepted for publication June 22, 2004.
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Abstract
Introduction
