INTRODUCTION

The rhabdomyosarcoma is an aggressive tumour accounting for 5-8% of all pediatric malignancies and for over 50% of all soft tissue sarcomas in children (1-5). It is considered a malignant neoplasia derived from striated muscle arising in any part of the body, however, it is more common in regions of the head and neck, genitourinary tract, retroperitoneum and extremities (3-5). Approximately 30% of all pediatric rhabdomyosarcomas occur in the head and neck and common sites of origin are the orbits, base of the skull, nasal cavity and nasopharynx. In nasopharynx, usually, it involves the middle ear, paranasal sinus and masticatory space (5).

Rhabdomyosarcomas are classified based on histopathologic features, which have distinct clinical characteristics: embryonal (the most common type in infants and young children), alveolar, botryoid, spindle cell and anaplastic variants (6).

The purpose of this study is to report a case of middle ear and temporal bone embryonal rhabdomyosarcoma associated with exudative otitis media emphasizing both clinical and radiological findings.


CASE REPORT

A boy, aged 4 years, presenting otalgia and irritability for the last 30 days where was diagnosed an otitis media. After a short course of antibiotics and analgesics the child developed deviation of the eye to the right, facial paralysis, and hearing impairment on the right.

The neurologic examination findings included facial and abducens nerve palsy on the right. The otoscopic examination showed a fragile and reddish tissue in the external acoustic meatus. The tympanic membrane was intact presenting hyperemia and bulging. Pure-tone audiometry detected a 45-dB hearing loss in this ear. There was no detectable lymphadenopathy on palpation.

A computed tomography (CT) of the head showed destruction of the petrous part of temporal bone and right carotid canal associated another lesion with soft-tissue component in the right frontal bone (Picture 1). The magnetic resonance imaging (MRI) showed lesions hypointese in T1-weighted sequences and hyperintense in T2-weighted sequences (Picture 2) with contrast enhancement (Picture 3) located in the petrous part of right temporal bone, middle ear and clivus. In association, it was observed a lesion in the right frontal bone along with the coronal suture.

The impairment of the right abducens nerve has occurred by involvement of Dorello canal and the facial and vestibulocochlear nerve by involvement of the internal acoustic meatus and the ipsilateral tympanic cavity.

Biopsy of the right external acoustic meatus showed chronic otitis externa with granulation tissue and rare atypical cells. The immunohistochemical methods confirmed, through the antibody expressions for desmin and myogenin, the diagnosis of embryonal rhabdomyosarcoma.

The tumor was resected by radical mastoidectomy via postauricular with meatoplasty and the child was started on multiagent chemotherapy and radiotherapy.

This study was approved by the Ethics Research Committee of the Institution.

Picture 1. CT showed destruction of the petrous part of temporal bone, carotid canal on the right (A,B) and right frontal bone (C,D).

Picture 2. MRI T2 weighted images showed synchronic hyperintense lesions with soft-tissue component located in the petrous part of right temporal bone extending to the sphenoid and clivus (A,B,C) and associated with lesion of right frontal bone (D).

Picture 3. MRI T1 weighted images showed hypointese lesion located in the petrous part of right temporal bone (A), with contrast enhancement (B,C) and associated with lesion of right frontal bone (D).

DISCUSSION

Embryonal is the most common histologic subtype of rhabdomyosarcomas. It is responsible for 70 to 80% of the presentations and its origin is supposed to be triggered by a disorder in mesenchymal primitive differentiation of the musculoskeletal cells in their first or earliest stages of embryogenesis (3,7,8).

Rhabdomyosarcomas may have their origin in any anatomical localization occurring predominantly in head and neck regions, orbits, skull base, nasal cavity, and nasopharynx where there is little or no musculoskeletal tissue (1,9). In pediatric cases, about 30 to 40% occur in the head and neck regions (10), however, the ear and the temporal bone are uncommon sites of involvement (7,8,11).

Middle ear rhabdomyosarcomas were reported in the literature with a range of symptoms that clinically simulates chronic otitis media. The most commons are facial nerve palsy, headache, hearing impairment, and bleeding (5). However, the findings of facial palsy with involvement of nerve roots and lesions of the perineural and parameningeal spaces are more suggestive of malignancy. Enlarged lymphonodes are more likely associated with distant metastasis (5,7).

Metastasis can be present in up to 30% of the cases. The most common affected sites are the lungs, liver, bones and extremities (5,12). In our case, the early diagnosis was otitis media followed of the paralysis of the cranial nerves by involvement of the space perineural and presence of distant frontal bone lesion.

The MRI study is the exam of choice because it more precisely defines the extent of tumor, as well as its signal pattern, boundaries, and post-contrast enhancement (13,14). In the case reported the lesion presented predominantly hyperintense in T2-weighted sequences, hypointense in T1-weighted sequences with homogeneous contrast enhancement and impairment of the perineural space.

Rhabdomyosarcomas affecting the perineural and parameningeal spaces, nasopharynx, paranasal sinuses, and temporal bone, generally are not amenable to surgical resection. In these areas, there is increased risk of serious damage to cranial nerves and deformation of the facial skeleton by radical surgery, and it is unlikely to complete resection. The treatment of choice for these tumors is chemotherapy and radiotherapy, with surgery limited to diagnostic biopsy (7,11).

Plexiform neurofibromas, juvenile angiofibroma, non-Hodgkin lymphoma, nasopharyngeal carcinoma, histiocytosis and cholesteatoma must be included among the differential diagnosis (15).

The diagnosis of middle ear and the temporal bone rhabdomyosarcoma is difficulted when associated inflammatory-infectious diseases, such as exudative otitis media that may mask the base disease and delay the definite diagnosis. In these cases, early correlation with imaging screenings is essential.


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1. PhD. Radiologist.
2. Master. Radiologist.
3. Specialization in Pathology. Pathologist.
4. Specialization in Radiology. Radiologist.
5. PhD. Head of the Department of Radiology.

Institution: Faculdade de Medicina de São José do Rio Preto - Hospital de Base. São José do Rio Preto / SP - Brazil. Mail address: José Roberto Lopes Ferraz Filho - Av. Brigadeiro Faria Lima, 5544 - São José do Rio Preto / SP - Brazil - Zip code: 15090-000 - Telephone: (+55 11) 3201-5743 - E-mail: jrl.ferraz@terra.com.br. Article received on December 15, 2008. Article accepted on July 4, 2009.