Abstract
Embryonal rhabdomyosarcoma of external ear canal is very rare, even in the pediatric population. We report an embryonal rhabdomyosarcoma of external acoustic canal, occurring in a 12-year-old Chinese girl who presented with left ear canal mass. Wide local excision of the mass was done under local anesthesia. Histopathological examination revealed the diagnosis. She then underwent 20 cycles of radiotherapy. CECT scan post treatment showed clearance of tumor cell. Now, patient is disease free for 5 years. We believe that early diagnosis followed by complete resection of the tumor with clear margin and radiotherapy improves the prognosis of the disease.
1
Introduction
Rhabdomyosarcoma arises from immature mesenchymal cells that are committed to skeletal muscle differentiation. It is commonly classified as embryonal, alveolar, pleomorphic, and mixed types. It is the most common soft tissue sarcoma in pediatrics, accounting for 5%–10% of all childhood malignancies with a relative predilection for the head and neck region with a rate about 40% . Rhabdomyosarcoma of external ear canal is extremely rare, thus making the early diagnosis challenging.
2
Case report
A 12-year-old Chinese girl presented with left ear canal mass which was increasing in size in 6 months’ duration. Examination showed a lobulated mass at the left external acoustic meatus measuring 2 × 1 cm with a wide base. Wide local excision was successfully done under local anesthesia. Histopathological examination revealed embryonal rhabdomyosarcoma. HRCT Temporal post excision showed no evidence of residual tumor or local infiltration. CT scan, ultrasonography of hepatobiliary system and chest x-ray were done and showed no evidence of metastasis or lymph node involvement. She then underwent 20 cycles radiotherapy. Repeat CT scan of temporal bone and neck showed no focal mass at external ear canal. On regular follow up as outpatient for over 5 years after the diagnosis, patient is well and free of recurrence.
2
Case report
A 12-year-old Chinese girl presented with left ear canal mass which was increasing in size in 6 months’ duration. Examination showed a lobulated mass at the left external acoustic meatus measuring 2 × 1 cm with a wide base. Wide local excision was successfully done under local anesthesia. Histopathological examination revealed embryonal rhabdomyosarcoma. HRCT Temporal post excision showed no evidence of residual tumor or local infiltration. CT scan, ultrasonography of hepatobiliary system and chest x-ray were done and showed no evidence of metastasis or lymph node involvement. She then underwent 20 cycles radiotherapy. Repeat CT scan of temporal bone and neck showed no focal mass at external ear canal. On regular follow up as outpatient for over 5 years after the diagnosis, patient is well and free of recurrence.
3
Discussion
Rhabdomyosarcoma represents the most common head and neck sarcoma in the pediatric population. The localization in external ear canal is very rare. H. Charchi in 2010 reported that only 3.75% of the head and neck rhabdomyosarcomas arise from the ear canal . Diagnosis of auricular rhabdomyosarcoma could be delayed by its clinical resemblance to more common and benign lesion in pediatrics such as chronic otitis with otorrhea and aural polyp . In this case, she presented with progressively enlarging aural mass that was obvious on inspection, without history of otorrhea or infection, which increased our index of suspicion of malignant tumor. In one reported series of 50 patients that presented with ear mass, the most common causes of ear mass were inflammatory polyps (20) followed by cholesteatoma (12), chronic non specific inflammation (7), abscess (1), malignancies; squamous cell carcinoma (7), embryonal rhabdomyosarcoma (1) and other benign lesions; carcinoid tumor (1) and nevus (1) .
The histopathological examination was essentially required with the support of immunohistochemical studies to make diagnosis. Histologically, rhabdomyosarcoma was one of small round blue cell in childhood like neuroblastoma, lymphoma and Ewing’s sarcoma, and embryonal rhabdomyosarcoma was characterized by primitive spindle cells, often with a myxoid background . Immunohistochemical studies, including staining for desmin, smooth muscle actin and myogenin, are additional studies that can support the diagnosis of rhabdomyosarcoma . ( Figs. 1, 2 )
