Rhabdomyosarcoma of the Adult Nasopharynx：A Case Report

Correspondence and requests for reprints : Dr. Chen-Hua Tsai

Address : 362, Chung Cheng Road, Hsintien City, Taipei County, Taiwan 23137

Introduction

Soft tissue sarcomas account for 15-20% of all pediatric malignancies, of which rhabdomyosarcoma is the most common. Rhabdomyosarcoma may be defined as a malignant tumor of the rhabdomyoblasts with a microscopic picture simulating that of striated muscle cells. In children and young adults, rhab-

domyosarcoma tends to occur in the head and neck, extremities, and genitourinary tract

. In contrast, rhabdomyosarcoma rarely occurs in the adult head and neck but commonly presents as truncal and ex- tremity tumors. The relative proportion of pleomor- phic tumors also increases with age. Rhabdomyosar- coma is classified into two major histologic subtypes, namely, juvenile (embryonal and alveolar) and adult

Rhabdomyosarcoma

of the Adult Nasopharynx A Case Report

Yueh-Lan Huang, Chin-Feng Tseng, Li-King Yang, and Chen-Hua Tsai

Abstract

Rhabdomyosarcoma is a rare and highly malignant neoplasm of the adult head and neck with a significant incidence of metastases. The outcome for adults with this disease is poorly documented.

Despite its ominously poor prognosis, combined polychemotherapy, radiotherapy and surgery, whenever feasible, has markedly improved survival rates in some patients. We report the case of a 67- year-old man who presented with a three-week history of a rapidly growing mass on the right upper neck with no symptoms of nasal obstruction, pain in the ears, tinnitus, or headache. Magnetic reso- nance image (MRI) study of the head and neck revealed a mass in the right and posterior walls of the nasopharynx with extension to the right parapharyngeal space, sphenoid and ethmoid sinuses and en- larged bilateral cervical lymph nodes extending from the submandibular to the supraclaricular regions.

Nasopharyngeal biopsy showed poorly differentiated small, blue round cells. A diagnosis of rhab- domyosarcoma was confirmed by positive staining for myo D1, myogenin, desmin and CD56.

Combination chemotherapy with VAC (vincristine, adriamycin and cyclophosphamide) regimen and ra- diotherapy was completed within 5 months. Follow up MRI of the head and neck, bone scan and chest X-ray 18 months later revealed neither local recurrence nor distant metastasis. ( J Intern Med Taiwan 2005; 16: 146-150 )

Key Words Rhabdomyosarcoma, Adult nasopharynx, Radiotherapy, Chemotherapy

Division of Oncology, Department of Internal Medicine,

Cardinal Tien Hospital

pleomorphic

. Due to nonspecific initial manifesta- tions, diagnosis is often made late in its course.

Metastatic disease most commonly occurs in the lungs, bone marrow, bones, liver and brain, and poor response to chemotherapy are strongly associated with worse prognosis

. However, combined chemo- therapy and radiotherapy have considerably im- proved survival in recent years

.

Case report

A 67-year-old man presented with a three-week history of a rapidly growing, non-tender mass in the right cervical region. Upon consultation with an otorhinolaryngologist, he was told to have nasopha- ryngeal cancer with cervical lymph node metastases.

Nasopharyngeal biopsy revealed poorly-differentiat- ed small blue round cells but no definitive diagnosis was given. He was subsequently referred to our Oncology clinic for further evaluation and manage- ment.

Physical examination revealed the presence of two confluent fixed, firm non-tender masses, one on each side of both upper cervical regions ( 7x7x5 cm on the right side and 5x6.5x4 cm on the left side, re- spectively ), and a protruding mass in the right na- sopharyngeal cavity. However, the patient was aymp- tomatic and denied having symptoms of nasal ob- struction, pain in the ears, tinnitus, nor headache.

Magnetic resonance image (MRI) study of the head and neck showed a mass in the right and posterior walls of the nasopharynx with extension to the right parapharyngeal space and enlarged bilateral cervical lymph nodes extending from the submandibular to the supraclavicular regions (Fig.1).

A second biopsy revealed a tumor with small to medium-sized blue round cells, many of which had eccentric nuclei and eosinophilic cytoplasm and some tumor cells with scanty cytoplasmic substance.

Postive immunohistochemical staining for desmin, myo D1, myogenin, CD56 and actin was compatible with a diagnosis of rhabdomyosarcoma (Fig. 2). The

cytokeratin stain was negative. Systemic work-up in- cluding bone scan, bone marrow biopsy, chest X-ray and abdominal sonography revealed no metastatic le- sion. Three courses of chemotherapy with vincristine ( 1.4mg/m

), adriamycin ( 50mg/m

), cyclophos- phamide ( 750mg/m

) and cisplatin ( 70mg/m

) every 4 weeks were given with granulocyte colony- stimulatory factor ( G-CSF ) 5mcg/kg/d support.

However, the patient still developed one episode of severe febrile neutropenia ( absolute neutrophil count less than 50/cmm ) after the second course of chemotherapy. Radiotherapy (4500cGy in 180cGy/fx) and biweekly vincristine ( 1.0mg/m

) were given for maintenance therapy. The entire course of treatment Fig. 1. Axial and coronal section T1-weighted MRI scan showing a mass (arrow), 7x7x5 cm in the right and posterior wall of the nasopharynx with extension to the right parapharyngeal space with enlarged bilateral cervical lymph nodes from the sub- mandibular to the supraclavicular regions.

Fig. 2. The tumor cells stained positive for myoD1, myo-

genin, CD56 which were compatible with a diag-

nosis of rhabdomyosarcoma. (Immunohistochem-

ical staining x 200)

was completed within 5 months. Follow-up MRI of the head and neck ( Fig. 3 ), bone scan, and chest X- ray done 18 months later revealed neither local re- currence nor distant metastasis.

Discussion

Rhabdomyosarcoma, a tumor derived from me- senchymal tissue, was first described by Weber in 1854

. It is the most common malignant tumor in chil- dren but is quite rare in adult

. Thus, current litera- ture regarding rhabdomyosarcoma is mostly derived from pediatric research studies .This tumor can de- velop anywhere due to its myogenic nature but oc- curs mostly in the head and neck, genitourinary tract, and extremities of children. In adults, the proximal part of the extremities and the genitourinary tract are the most common sites

. There are four histologic variants, namely, embryonal, alveolar, pleomorphic and undifferentiated. However, some authorities have proposed that there are only two major variants, that is, the juvenile (embryonal and alveolar) and the adult pleomorphic forms. Unfortunately, accurate histo- logic classification was limited by insufficient biop- sy specimen in this patient.

Sarcomas develop from connective tissues such as muscles, fat, and membranes lining joints or blood vessels. However, nasopharyngeal carcinoma usual- ly originates from cells lining the oropharynx or that

part of the pharynx which lies behind the oral cavity.

Patients with nasopharynx cancer may notice a lump in the neck or develop pain or ringing in the ears. Patients may also complain of impaired hear- ing, frequent headaches. However, the primary lesion in head and neck rhabdomyosacroma usually presents as a non-tender mass or localized swelling with no accompanying nasopharyngeal symptoms, which is how our patient presented.

Since histopathologic finding in this patient re- vealed poorly differentiated small, blue round cells, differential diagnosis had to include extraskeletal Ewing's tumor, primitive neuroectodermal tumor, neuroblastoma, malignant lymphoma, or intra-ab- dominal desmoplastic small round cell tumor.

However, positive immunohistochemical staining for desmin, myo d1, myogenein, CD56 and actin is com- patible with a diagnosis of rhabdomyosarcoma in our patient.

In nasopharyngeal rhabdomyosacroma, the lungs and bones are the usual sites of distant metas- tasis. Newman and Rice reported distant metastases in 50% of their patients after treatment, 62% of whom had local recurrence prior to the development of metastasis. Moreover, 90% of distant metastases oc- curred 2 years after treatment, and the 5-year survival rate of patients with distant metastases was a dismal 0%

. Staging study in our patient showed tumor ex- tension to the right parapharyngeal space, with en- larged bilateral neck lymph nodes from the sub- mandibular area to the supraclavicular regions.

Management of rhabdomyosarcoma usually in- volves a combination of surgery, radiotherapy and chemotherapy. Total tumor resection confers the most favorable treatment outcome. However, complete tu- mor resection is often difficult because of its invasive nature of the tumor and its often anatomically can- celed location

. Overall prognosis for rhabdomyosar- coma has improved since the introduction of multi- disciplinary treatment

but prognosis remains poor for patients with metastatic disease at presentation and Fig. 3. Eighteen months after therapy, MRI of the neck and

nasopharynx revealed neither local recurrence nor

distant metastasis.

poor response to chemotherapy

. Radiotherapy is tar- geted at the pre-chemotherapy sites of disease.

Chemoradiation following complete surgical resec- tion appears to be the ideal therapy

. Since the adult head and neck rhabdomyosarcoma is biologically different from tumors occurring in children, there is little evidence to support any particular therapeutic program

. The optimal treatment remains undefined and multimodal approaches combining surgical re- section, radiation, and systemic chemotherapy need further investigation.

In conclusion, adult nasopharyngeal rhab- domyosarcoma rarely occurs but should be kept in mind, nevertheless, the differential diagnosis of a head or neck mass and biopsy finding of poorly dif- ferentiated small blue round cells.

Despite its poor outcome and severe complica- tions, adequate local control of adult rhabdomyosar- coma may be attainable with multidisciplinary treat- ment and proper supportive care.

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myoD1 myogenin desmin CD56

( VA C

vincristine, adriamycin and cyclophosphamide ) (

X )