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Embryonal rhabdomyosarcoma of the temporal bone.

Abstract

The most common soft-tissue sarcoma in infants and children is rhabdomyosarcoma. The head and neck is the most common site of involvement; temporal bone involvement has been seen in about 7% of reported cases. Multimodality therapy--surgery, multiagent chemotherapy, and radiotherapy--yields sufficiently good results. The author reports a case of embryonal rhabdomyosarcoma of the temporal bone with cranial nerve palsies and extension into the parapharyngeal space in a 4-year-old boy. Despite surgery and chemotherapy, the patient died of his disease within 3 months of presentation.

Introduction

Approximately 77% of all rhabdomyosarcomas occur in patients younger than 12 years of age, and 43.5% occur in those younger than 5 years. (1) Rhabdomyosarcoma is the most common soft-tissue sarcoma in infants and children, and the most common site of involvement in this age group is the head and neck. It is the only notable malignancy of the middle ear seen in children, although it is uncommon at that site. (1) It is a highly aggressive tumor that until a few decades ago was always fatal.

Since 1972, the Intergroup Rhabdomyosarcoma Study Group has been investigating and refining the treatment protocol for rhabdomyosarcoma. According to this group, the mainstay of therapy for patients younger than 21 years is surgery (for complete resection when possible, and for biopsy when complete resection is not possible), multi-drug chemotherapy, and radiation therapy. (2)

In this article, the author reports a case of embryonal rhabdomyosarcoma of the temporal bone with cranial nerve palsies and extension into the parapharyngeal space.

Case report

A 4-year-old boy was brought to the ENT clinic for evaluation of a discharge from his right ear of 2 months' duration and an inability to close his right eye of 7 days' duration. The discharge was purulent, foul-smelling, and associated with pain and hearing loss; it was not blood-tinged. Examination of the right external auditory meat-us revealed that it was filled with a reddish polypoid mass. The mass did not bleed when touched. The patient also had infranuclear facial paralysis on the right side (figure 1). The regional lymph nodes were not enlarged, and findings on the remainder of the ENT examination were normal.

[FIGURE 1 OMITTED]

The results of routine blood and urine examinations were within normal limits. X-ray of the mastoid showed areas of rarefaction on the right side. Pure-tone audiometry detected a 45-dB hearing loss in the right ear. The provisional diagnosis was unsafe chronic suppurative otitis media (CSOM) with an aural polyp and facial paralysis.

With the patient under general anesthesia, a radical mastoidectomy via a postauricular approach was performed. Intraoperatively, the mastoid cavity, middle ear, and external ear were filled with a fragile, reddish mass. The ossicles and tympanic membrane had been destroyed, and dehiscence was seen in the descending portion of the fallopian canal. A meatoplasty was performed, and the wound was closed. Histopathologic examination of the excised mass revealed that it was an embryonal rhabdomyosarcoma (figure 2).

[FIGURE 2 OMITTED]

At follow-up 1 month later, the lateral rectus palsy persisted (figure 3, A), and a parapharyngeal mass had pushed the right tonsil toward the midline (figure 3, B). Computed tomography was not performed because the patient's parents could not afford it. The child was started on multiagent chemotherapy with vincristine 1.4 mg/[m.sup.2], doxorubicin 50 mg/[m.sup.2], and cyclophosphamide 700 mg/[m.sup.2]. However, he died of his disease within 2 months.

[FIGURE 3 OMITTED]

Discussion

Rhabdomyosarcoma is a highly malignant tumor of mesenchymal origin. Among the general population, it occurs primarily in the urogenital tract; it has also been reported in the orbit, nasopharynx, palate, temporal bone, tonsil, and neck. (1) Temporal bone involvement has been seen in approximately 7% of reported cases. (2) In the temporal bone, rhabdomyosarcomas arise in middle ear, extend to the mastoid and petrous portions of temporal bone, and eventually invade the cranium. The propensity for local invasion and destruction is characteristic of rhabdomyosarcoma, and rapid regional spread is pathognomonic.

Classification. In the early 20th century, Rakov was one of several pathologists who emphasized the sarcomatous nature of many of these tumors, and in 1937 he offered a set of histologic diagnostic criteria. (3) In 1946, Stout delineated the histopathologic features of sarcomas of skeletal muscle origin. (4) In 1958, Horn and Enterline published the most useful classification of rhabdomyosarcomas; they classified them as pleomorphic, alveolar, embryonal, and botryoid. (5) Infants and children generally have one of the latter two types. (1)

Clinical features. Rhabdomyosarcoma of the temporal bone often presents as a relatively innocuous-appearing condition, a fact that can result in a significant delay in diagnosis. The two most common presenting features are discharge from the ear with granulation tissue and the presence of a polypoid mass. Facial paralysis may be present at the first visit, or it may appear in due course. In our patient, the facial nerve was involved early in the course of his disease. His rhabdomyosarcoma arose from the middle ear and involved the mastoid. Later, the VIth cranial nerve and parapharyngeal space became involved.

Patients with a rhabdomyosarcoma that has spread predominantly to the petrous portion of the temporal bone present in different ways clinically. They usually experience persistent headache (usually frontal) and early abducent nerve paralysis caused by apical involvement and extension into Dorello's canal. An absence of VIIth cranial nerve symptoms is an important factor in distinguishing a predominantly petrous rhabdomyosarcoma from a middle ear or mastoid rhabdomyosarcoma; in the latter two cases, facial paralysis is always an early symptom. (6) Rhabdomyosarcomas can also affect cranial nerves III, V, and VI. (7)

Prat and Gray reviewed the presenting signs and symptoms in 50 patients with embryonal rhabdomyosarcoma reported by various authors. (8) They included a mass in the area of the ear (n = 28; 56%), a polyp in the ear canal (n = 27; 54%), aural discharge (n = 20; 40%), aural bleeding (n = 15; 30%), earache (n = 11; 22%), deafness (n = 7; 14%), and cranial nerve VII palsy (n = 7; 14%). Other findings were an abnormal mastoid on x-ray (n = 27; 54%) and cranial hypertension (n = 9; 18%).

Stages. Three stages of rhabdomyosarcoma are generally recognized (6):

* In stage I, the neoplasm is limited to the middle ear, and it produces symptoms similar to those of otitis media.

* In stage II, intratemporal bone expansion occurs, causing pain, hearing loss, and facial nerve paralysis.

* Stage III (the terminal stage) is characterized by brain, neck, infratemporal, and parapharyngeal space invasion, with or without metastasis.

Our patient presented with stage II disease. However, by the second visit his disease had progressed to stage Ilk His mass involved the parapharyngeal space; no metastasis was seen.

Diagnosis. Most patients with rhabdomyosarcoma of the middle ear and temporal bone are diagnosed late in the course of the disease. Meningeal extension remains the major obstacle to a good outcome. A painless polyp of unusual appearance with facial nerve palsy and mastoid air cell destruction should suggest to the clinician the possibility of a malignancy in the middle ear. Early biopsy of an aural polyp or granulation tissue may lead to early detection before meningeal extension.

Another factor of great interest in the literature is the frequency of pathologic misdiagnosis of rhabdomyosarcoma. (1) No other tumor of childhood is so often misdiagnosed. Some 50% of the histologic diagnoses of proven cases of rhabdomyosarcoma were incorrect on initial biopsy. (7)

Microscopically, embryonal rhabdomyosarcomas are pleomorphic. Its cells are elongated, and they feature hyperchromatic nuclei and occasional cytoplasmic projections. Mitosis is frequent in embryonal rhabdomyosarcoma. Cross-striations are present only in some cases, and therefore they are not essential for diagnosis. (6)

In the report by Prat and Gray, 31 of the 50 patients (62%) experienced a delay in diagnosis after their first symptom had manifested. (8) In 13 of these patients, a delay of between 1 and 5 months was attributable to a misinterpretation of a biopsy of granulation tissue. We had difficulty establishing a diagnosis in our patient because his clinical features resembled those of CSOM of the unsafe variety. The final diagnosis was not established until after the postmastoidectomy histopathology report had been received.

Tumor spread. Rhabdomyosarcomas of the middle ear cleft spread by invading and destroying the fallopian canal. This canal appears to be a vulnerable area through which tumors may extend unobstructed into the internal auditory meatus and posterior cranial fossa. (9)

Other possible means of intracranial extension from the temporal bone include (2):

* extension into the middle cranial fossa through the mastoid and tympanic tegmen, leading to involvement of the temporal lobe

* extension into the vestibular or cochlear aqueducts following invasion of the labyrinth

* inferior extension through the jugular bulb, styloid process, and carotid artery

* direct extension from the infratemporal fossa or nasopharynx

Tumor extension along the eustachian tube--either from the nasopharynx to the middle ear or vice versa--is also possible. (2) Prat and Gray reported 1 case of extension along the facial nerve and through the internal auditory meatus that culminated in encasement of the base of the brain and entire spinal cord (massive neuraxial spread); there was no systemic metastasis. (8)

The lung is the most common site of distant metastasis; other sites include the skeletal system, liver, brain, breast, and intestines. (2) Khurana et al reported a case that featured distant metastases to the liver and spinal cord. (10) Raney et al reported that regional lymph node metastasis is rare in cases of rhabdomyosarcoma of the middle ear. (11)

The essential growth characteristic is rapid local spread beyond the confines of any attempted therapy, although the response to therapy within the surgical or radiotherapeutic boundaries may be complete. (1) The tumor has a high tendency for meningeal extension at the time of primary diagnosis. (2)

In our patient, the rhabdomyosarcoma arose in the middle ear, extended into the external auditory canal as an aural polyp, and continued to extend into the mastoid, involving the facial nerve along the way. By the time of his second visit, the tumor had involved the VIth cranial nerve and extended into the parapharyngeal space. This spread might have occurred directly or through the eustachian tube.

Treatment. All treatment modalities--surgery, chemotherapy, and radiotherapy--can be employed, but results are mixed. One Intergroup Rhabdomyosarcoma Study Group study published in 1983 showed that a combination of surgery, multiagent chemotherapy, and radiotherapy resulted in good long-term survival in patients with this once-uniformly fatal disease. (11) This is in contrast with a report published in 1965 by Masson and Soule, who reported a 55% mortality within the first year and 88% within 5 years. (12)

Acknowledgment

Thanks are due to Dr. Kishore Chandra Prasad for his help in the preparation of this report.

References

(1.) Barnes PH, Maxwell MJ. Embryonal rhabdo-myosarcoma of middle ear: Report of a case with 12 years' survival with a review of the literature. J Laryngol Otol 1972;86:1145-54.

(2.) Wiatrak BJ, Pensak ML. Rhabdomyosarcoma of the ear and temporal bone. Laryngoscope 1989;99:1188-92.

(3.) Rakov AI. Malignant rhabdomyosarcomas of the skeletal musculature. Am J Cancer 1937;30:455-76.

(4.) Stout AP. Rhabdomyosarcoma of the skeletal muscles. Ann Surg 1946; 123:447-72.

(5.) Horn RC Jr., Enterline HT. Rhabdomyosarcoma: Aclinicopathological study and classification of 39 cases. Cancer 1958;11:181-99.

(6.) Canalis RF, Gussen R. Temporal bone findings in rhabdomyosarcoma with predominantly petrous involvement. Arch Otolaryngol 1980;106:290-3.

(7.) Feldman BA. Rhabdomyosarcoma of the head and neck. Laryngoscope 1982;92:424-40.

(8.) Prat J, Gray GF. Massive neuraxial spread of aural rhabdomyosarcoma. Arch Otolaryngol 1977;103:301-3.

(9.) Myers EN, Stool S, Weltschew MA. Rhabdomyosarcoma of the middle ear. Ann Otol Rhinol Laryngol 1968;77:949-58.

(10.) Khurana AS, Bawa GS, Singh J. Embryonal rhabdomyosarcoma. Indian J Otolaryngol 1987;39:125-6.

(11.) Raney RB Jr., Lawrence W Jr., Maurer HM, et al. Rhabdomyosarcoma of the ear in childhood. A report from the Intergroup Rhabdomyosarcoma Study-1. Cancer 1983;51:2356-61.

(12.) Masson JK, Soule EH. Embryonal rhabdomyosarcoma of the head and neck. Report on eighty-eight cases. Am J Surg 1965;110: 585-91.

Borlingegowda Viswanatha, MS, DLO

From the ENT Department, Victoria Hospital, Bangalore Medical College, Bangalore, Karnataka, India.

Reprint requests: Dr: Borlingegowda Viswanatha, #716, 10th Cross, 5th Main, MC Layout, Vijayangar, Bangalore-560 040, Karnataka, India. Phone: 91-80-2338-1567; fax 91-80-2599-7391; e-mail: drbviswanatha@yahoo.co.in
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Author:Viswanatha, Borlingegowda
Publication:Ear, Nose and Throat Journal
Article Type:Disease/Disorder overview
Date:Apr 1, 2007
Words:2049
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