| Abstract|| |
Ewing's sarcoma represents 10% of all primary malignant bone tumors . These are primarily seen in long bones. Primary Ewing's sarcoma involving the cranial bones are rare and only 13 cases involving the temporal bone have been reported in literature to the best of our knowledge. Considering its rarity, we report a case of Ewing's sarcoma of the temporal bone. Salient clinical, radiological and histologic features are described.
Keywords: Ewing′s sarcoma, Temporal bone
|How to cite this article:|
Bawa S S, Hegde K K. Primary ewings sarcoma of the temporal bone- a case report. Indian J Radiol Imaging 2006;16:623-5
| Case report|| |
A nine year old boy presented with swelling over right temporal region of scalp of 20 days duration. It was sudden in onset, gradually progressive to attain a size of a lemon (8 x 6cm) at the time of presentation. The swelling was painless except for stretching pain which was due to the involvement of the facial nerve.
Examination confirmed the temporal swelling extending superficial and deep to skull bone, firm in consistency mild deep tenderness with signs of LMN facial nerve palsy on same side. There was no clinical correlative of intracranial dysfunction.
" CT showed that the lesion was based in the right temporal bone involving the squamous, petrous and mastoid portions with sharp margins from brain parenchyma. The mass was Hyperdense on plain scans and showed enhancement. There was extensive involvement of the outer and inner table of the cranium. [Figure - 1],[Figure - 2]
" Ultrasound abdomen was normal, there was no organomegaly. Adrenals were normal. Ultrasound thorax was normal.
" Skeletal survey with radiographs revealed no other extracranial lesion.
" Differential diagnostic consideration included rhabdomyosarcoma, metastasis eosinophilic granuloma and cholesteatoma.
The biopsy revealed:
Microscopy: Multiple sections studied are showing bits of tumor tissue with destruction of bone. Lesion is a small round cell tumour having cells with scanty cytoplasm and dark hyper chromatic nuclei. These cells are in groups and sheets separated by myxoid to desmoplastic stroma mitosis not very obvious. Focally cells have clear cytoplasm.
" Haematological evaluation was normal in Hb%, CBC, ESR and further peripheral smear didn't show any abnormal cells.
" Decompression of expanding cranial mass was done by neurosurgery and tissue was sent for histopathological report.
| Discussion|| |
In 1921 James Ewing described a lethal primary bone lesion that affects children and young adults and most frequently originates in the long bone (47%) pelvis (19%) or ribs (12%) . The skull is rarely involved, probably in less than 4% cases with the frontal and parietal bones being the most commonly affected ,
These tumors rarely arise in soft tissue. Classically Ewing's sarcoma presents as a diaphyseal permeative lesion with a characteristic onion peel periosteal reaction resulting from new bone formation in parallel layers with mottling, cortical erosion and bone expansion . However these pathogenic features are often absent.
CT of Ewing's sarcoma has often shown a diffusely enhancing hyperdense extra axial mass and extensive bone destruction involving both inner and outer table ,,,. Bone involvement by the lesion and bone healing by chemotherapy are better demonstrated on CT scans. MR imaging although providing better delineation of the soft tissue component has a limited role in the treatment of these patients. Bone scans indicate increased uptake in the region of the tumours, suggesting an ossification process. Isotope scans are useful for identification of extracranial bone involvement .
The significance of this case lies in the fact that there is only one reported case of Ewing's of squamous part of temporal bone . The involvement of the petrous, mastoid and squamous part in the same individual has not been reported before to the best of our knowledge. [Figure - 3][Figure - 4]
The histogenesis of Ewing's tumour has been controversial, and it seems possible that lesions diagnosed as Ewing's sarcoma may actually be a heterogenous group of analplastic neoplasms. More recently, many studies have confirmed the appearance of structures (such as scanty neurosecretory granules) that suggest that Ewing's sarcoma is a form of primitive peripheral neuroectodermal tumour .
The prognosis of extra cranial Ewing's sarcoma is reported to be poor, because of metastasis to long and other bones. In contrast infrequent metastasis appears to present biological characteristics of primary cranial Ewing's sarcoma 
Treatment includes radiation therapy along with chemotherapy with a 5 year survival of 8 to 24% ,.
Although a rare entity, Ewing's sarcoma of the temporal bone must kept in mind when diagnosing extra axial lesions involving the temporal bone in the paediatric age group.
| References|| |
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K K Hegde
Hegde Diagnostic Centre,C.G. Hospital Road, P.J. Extn.,Davangere - 577 004
Source of Support: None, Conflict of Interest: None
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4]