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Year : 2006  |  Volume : 16  |  Issue : 3  |  Page : 353-354
Primary Ewing's sarcoma of occipital bone


Department of Radiodiagnosis, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh - 160 012, India

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   Abstract 

Ewing's sarcoma commonly involves the long bones. Primary Ewing's sarcoma of the cranium is rare and is difficult to distinguish from other tumors involving the cranium. Radiological features and immuno-histochemistry are helpful in diagnosing this tumor. In this report we present a rare case of primary Ewing's sarcoma of the occipital bone and discuss the differential diagnostic options.

Keywords: Ewing′s sarcoma, occipital bone, radiology

How to cite this article:
Kaza R K, Sandhu M S, Ojili V. Primary Ewing's sarcoma of occipital bone. Indian J Radiol Imaging 2006;16:353-4

How to cite this URL:
Kaza R K, Sandhu M S, Ojili V. Primary Ewing's sarcoma of occipital bone. Indian J Radiol Imaging [serial online] 2006 [cited 2019 Dec 10];16:353-4. Available from: http://www.ijri.org/text.asp?2006/16/3/353/29015

   Introduction Top


Ewing's sarcoma of bone commonly involves the long bones. Primary cranial Ewing's sarcoma is rare and constitutes about 1% of all Ewing's sarcoma [1]. Involvement of occipital bone by primary cranial Ewing's sarcoma is uncommon [2]. We report an uncommon case of primary Ewing's sarcoma of the cranium involving the occipital bone.


   Case Report Top


A 12 year old male child was admitted with right sided headache for the last one year. He also complained of continuous pain in the right side of occipital region for the last one year. He complained of recurrent episodes of vomiting for the last one week. The physical examination and systemic examination was unremarkable. Computerized Tomography (CT) scan of the head was done without contrast and after administering intra venous contrast. It showed a 4 x 5 cm well defined extra axial lesion in the posterior fossa involving the occipital bone on right side [Figure - 1] a&b. The lesion was hyperdense on non contrast CT scan and showed intense and homogenous enhancement following contrast enhancement [Figure - 2]. There was destruction of the underlying occipital bone involving both the inner and outer tables. Minimal enhancing soft tissue was also present in the subcutaneous tissues in right occipital region. There were no areas of necrosis or hemorrhage noted within the tumor. There was compression of the fourth ventricle with mild dilatation of the third ventricle and lateral ventricles seen. Ultrasound of the abdomen and chest x-ray was normal. Blood tests including haemogram, liver function tests and renal function tests were normal.

Right parieto-occipital craniotomy was done and a large moderately vascular tumor, principally arising from the occipital bone and involving the dura was found which was totally excised. Postoperative CT scan was done which confirmed total excision of the tumor.

On histopathology the tumor showed malignant round cells arranged in sheets and few pseudorossetes were discernable. Immunohistochemistry and special stains were suggestive of Ewing's sarcoma.

The patient was subjected to local radiotherapy. The patient also received six cycles of combination chemotherapy of VAC protocol comprising Vincristine, Adriamycin and Cyclophosphomide. At 10 months follow up MRI of brain was done which showed no residual or recurrent tumor in the posterior fossa.


   Discussion Top


Ewing's sarcoma represents 6-9% of the primary malignant bone tumors and it commonly affects the long tubular bones [3]. Approximately 90% of patients are between the ages of 5 and 30 years at the time of presentation. Primary Ewing's sarcoma occurring in the cranium is exceptionally rare and constitutes about 1% of all Ewing's sarcomas [1]. The commonest site of primary cranial Ewing's sarcoma is the temporal bone followed by the frontal, parietal and occipital bones. Sphenoid and ethmoid bones are less commonly involved [4]. Primary cranial Ewing's sarcoma is usually seen in patients below the age of 20 years, with no sex predilection. The most common complaint is pain, usually intermittent in character. In cases of intracranial extension, headache, vomiting and papilloedema are common with localizing signs depending on the site [1].

Radiologically Ewing's sarcoma involving the long bones presents as a permeative pattern of bone destruction. Primary cranial Ewing's sarcoma also present as permeative destructive lesions with large associated soft tissue component, reflecting the aggressive nature of the tumor.

In our patient CT scan typically showed large extra-axial mass arising from and destroying the occipital bone. The 'onion peel' periosteal reaction typical of Ewing's sarcoma in long bones is usually not seen in primary cranial Ewing's sarcoma. The tumor was hyperdense on non-contrast CT scan which is characteristic of tumors with closely packed cells and having a high nuclear/cytoplasmic ratio. There was intense enhancement noted following contrast administration suggesting breakdown of the blood-brain barrier which is seen in majority of the tumor types. The differential diagnosis of tumors involving the skull with adjacent soft tissue in children would include metastatic neuroblastoma, lymphoma, rhabdomyosarcoma (skull base) and desmoplastic small round cell tumor. MRI usually shows primary cranial Ewing's sarcoma to be hypointense on T1-weighted and of mixed intensity or hyperintense on T2-weighted images, which enhances on giving intravenous gadolinium [5].

Primary cranial Ewing's sarcoma is reported to have a better prognosis as compared to Ewing's sarcoma elsewhere [2]. The treatment of choice is surgery followed by radiotherapy and systemic chemotherapy.

Primary cranial Ewing's sarcoma is to be considered in the differential diagnosis in children with a tumor involving the skull with destruction of the bone and presence of extra-axial soft tissue.

 
   References Top

1.Steinbok P, Flodmark O, Norman MG, Chan KW, Fryer CJ. Primary Ewing's sarcoma of the base of the skull. Neurosurgery. 1986 Jul;19(1):104-7.  Back to cited text no. 1    
2.Desai KI, Nadkarni TD, Goel A, Muzumdar DP, Naresh KN, Nair CN. Primary Ewing's sarcoma of the cranium. Neurosurgery. 2000 Jan;46(1):62-8; discussion 68-9. Review  Back to cited text no. 2    
3.Rosen G, Wollner N, Tan C, Wu SJ, Hajdu SI, Cham W, D'Angio GJ, Murphy ML. Proceedings: Disease-free survival in children with Ewing's sarcoma treated with radiation therapy and adjuvant four-drug sequential chemotherapy. Cancer. 1974 Feb;33(2):384-93.  Back to cited text no. 3    
4.Singh P, Jain M, Singh DP, Kalra N, Khandelwal N, Suri S. MR findings of primary Ewing's sarcoma of greater wing of sphenoid. Australas Radiol. 2002 Dec;46(4):409-11.  Back to cited text no. 4    
5.Watanabe H, Tsubokawa T, Katayama Y, Koyama S, Nakamura S. Primary Ewing's sarcoma of the temporal bone. Surg Neurol. 1992 Jan;37(1):54-8. Review.  Back to cited text no. 5    

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Correspondence Address:
M S Sandhu
House No. 220, Sector 9-C, Chandigarh - 160009
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0971-3026.29015

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    Figures

[Figure - 1], [Figure - 2]



 

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    Abstract
    Introduction
    Case Report
    Discussion
    References
    Article Figures

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