Iodine-125 brachytherapy for the treatment of a large parotid epithelial-myoepithelial carcinoma in a child

Abstract

Epithelial-myoepithelial carcinoma (EMC) in the salivary glands is rare. Tumours originating from salivary glands are also rare in children. Radical resection is the main treatment used for EMC in salivary glands. However, this surgery is commonly associated with functional and/or cosmetic deficits. There is also a high percentage of local recurrence after a tumourectomy. We present a typical case of recurrent EMC in the left parotid gland of an 8-year-old girl. The patient was treated with iodine-125 brachytherapy. At the 2-month follow-up, the tumour size was reduced by 80%, and at 1 year, no tumour tissue was detected on positron emission tomography/computed tomography. At the 6-year follow-up, no local recurrence or distant metastasis was found and no complications had occurred. Iodine-125 brachytherapy is a potentially appropriate alternative treatment for EMC in the salivary glands, especially for paediatric patients.

Epithelial-myoepithelial carcinoma (EMC) in the salivary gland is rare, with an incidence of less than 1% of all salivary gland tumours. EMC is now recognized as a low-grade malignant tumour. Radical excision is the main treatment for EMC. However, local recurrence is common after resection. Also the extent of the surgical excision often results in significant cosmetic and/or functional deficits.

We report the case of a female paediatric patient with a large EMC, who was treated successfully using iodine-125 brachytherapy.

Case report

Clinical history

An 8-year-old girl was referred to our hospital because of a recurrent tumour on the left parotid gland. Two years previously she had noted a painless tumour in the sub-auricular region on the left side. The tumour was 20 mm × 20 mm in size. She was diagnosed with a parotid gland tumour in a local hospital. The tumour and superficial lobe of the parotid gland were removed, with the left facial nerve preserved. Pathological examination of the tumour indicated EMC. She was not given any treatment after surgery. One year after surgery, the tumour recurred in the same region and grew slowly. She had no other symptoms except for the tumour, and the results of all laboratory tests (clinical chemistry and haematology) were within the normal ranges. She was then referred to our hospital.

On physical examination, there was a hard, immobile, painless, and irregular mass in the left sub-auricular region; the mass margin was not clear. Her facial movement was intact and mouth-opening movements were not limited. The superficial skin over the mass was normal. The parapharyngeal wall had not expanded. No enlarged lymph nodes were found in the neck.

A computed tomography (CT) scan revealed an enhanced tumour with cystic lesion; its margin was not clear and the tumour was approximately 70 mm × 70 mm × 60 mm in size, located in the left parotid gland region. The upper bound of the tumour was located inferior to the zygomatic bone and the lower bound was at the lingual bone level. The jugular artery and vein were not clear ( Fig. 1 ). Chest radiography showed no metastasis.

Fig. 1
CT scan showing a large tumour in the parotid region; the tumour margin is not clear.

Treatment

On 20 July 2007, a radical resection was planned and performed through a standard ‘lazy S’ cervicomastoid–pre-auricular incision. After the parotid gland and tumour were exposed, the facial nerve was found to be surrounded by the tumour and thus could not be preserved. The child’s parents refused to allow sacrifice of the facial nerve. Instead, a conserved tumour resection was performed. Pathological examination confirmed the tumour to be an EMC ( Fig. 2 ).

Fig. 2
Histopathology showing epithelial-myoepithelial carcinoma (haematoxylin and eosin stain; original magnification (a) 100×, (b) 200×).

The patient’s parents agreed to the use of iodine-125 seed implantation brachytherapy. Based on the CT scan, the tumour outline was defined as the clinical target volume (CTV) and 1 cm outside of the CTV was defined as the planned target volume (PTV). The prescribed dose was 120 Gy. The radioactivity of each seed was 0.8 mCi and it was planned to implant a total of 97 seeds. On 2 August 2007, 97 iodine-125 seeds were implanted in the target positions under CT guidance.

Follow-up

Two months after the iodine-125 seed implantation, the mass had decreased significantly in size. The functions of the facial nerve were normal and the girl had experienced no discomfort. A CT scan showed the tumour size to be reduced by about 80% ( Fig. 3 ).

Fig. 3
CT scan showing the tumour size reduced by about 80% at 2 months after the implantation.

One year later, no cancerous tissue could be detected on positron emission tomography/computed tomography (PET/CT). The skin had become rough and black. Six years later, a local physical examination was completely normal and the superficial skin had become normal. No local recurrence or distant metastasis was found ( Figs 4 and 5 ).

Jan 19, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Iodine-125 brachytherapy for the treatment of a large parotid epithelial-myoepithelial carcinoma in a child
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