Recurrent Mucoepidermoid Carcinoma of Parotid with Facial Tics-Report of an unusual case

We report an interesting case of a 21 year old male who presented with recurrent mucoepidermoid carcinoma of parotid with facial nerve involvement as facial tics. Intraoperatively, the tumour was noted to be fi rm, irregular and adherent to the underlying structures. The patient underwent extended total parotidectomy, division of buccal branch of facial nerve, selective neck dissection with cervical local rotational fl ap repair and post-operative radiotherapy. This presentation of Mucoepidermoid carcinoma with involvement of facial nerve as facial tics is one of the rare unique reported cases. Case Report Recurrent Mucoepidermoid Carcinoma of Parotid with Facial Tics Report of an unusual case Pirabu Sakthivel*, Chirom Amit Singh, Smriti Panda, Suresh Chandra Sharma, Konki Malla Abhilash and Milind Sagar Department of Otorhinolaryngology & Head and Neck surgery, All India Institute of Medical Sciences, India *Address for Correspondence: Dr. Pirabu Sakthivel, Department of Otorhinolaryngology and Head & Neck surgery, All India Institute of Medical Sciences, New Delhi, India, Tel: 9958744547; Email: pirabusakthivel@gmail.com Submitted: 03 June 2017 Approved: 14 June2017 Published: 16 June 2017 Copyright: 2017 Sakthivel P, et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited


INTRODUCTION
Mucoepidermoid carcinoma (MEC) of the salivary glands is believed to arise from pluripotent reserve cells of the excretory ducts that are capable of differentiating into squamous, columnar, and mucous cells [1]. Although MEC accounts for less than 10% of all tumors of the salivary gland, it constitutes approximately 30% of all malignant tumors of the salivary gland [2]. MEC is the most common malignant tumour to arise in children and adolescents under 20 years of age [3]. Due to the cellular heterogeneity, the histologic composition, biological behaviour, and clinical course of MEC vary. The tumour usually presents as an asymptomatic irm to hard mass. Pain and facial paralysis are associated with high grade malignant tumors. They can recur, and they can metastasize to regional lymph nodes or distant viscera [2,3]. Because of the relative rarity of these tumors and the remarkable variability in their biological behaviour, opinions differ about the appropriate classi ication, grading, and treatment [4]. Although surgery generally is accepted as the primary treatment for MEC, the extent of parotidectomy, the indications for neck dissection and need for adjuvant therapy are not clear [2,4].
We report an unusual unique case of recurrent MEC of right parotid gland with facial tics who underwent extended total parotidectomy, division of buccal branch of facial nerve, selective neck dissection with cervical local rotational lap repair and post-operative radiotherapy.

CASE REPORT
A 21year-old male presented to our outpatient department with painless progressive swelling in right parotid region associated with facial tics for the past 1 year. There was history of excision of the swelling before 2 years at local hospital and the patient was advised it was benign in nature, although no records were retrievable from the patient. After surgery the patient was asymptomatic for six months but he started developing painless progressive swelling of right parotid along with facial tics. Clinical examination revealed a irm, discrete, oval swelling of size 5x 3 cm with skin puckering along with healed preauricular scar ( Figure 1A). His facial nerve movements were intact but patient had facial tics (Video 1). No regional lymph nodes were palpable. MRI revealed an in iltrative mass lesion on the super icial lobe of the right parotid gland with both cystic and solid components ( Figure 1B,1C). Fine needle aspiration cytology [FNAC] reported it to be a MEC. The patient was planned for surgery under general anaesthesia. Intraoperatively, the mass was irregular and irmly adherent to masseter and skin with buccal branch of facial nerve completely engulfed in the tumour with few intraparotid lymph nodes, raising the suspicion of high grade malignancy. Extended total parotidectomy along with sacri ice of buccal branch of facial nerve with selective neck dissection was performed using modi ied Blair's incision ( Figure 2A). A local cervical rotational lap ( Figure 2B,2C,2D) was done to cover the skin defect and the wound was closed in layers after placing a drain. Post operatively, wound was well healed and patient had temporary lower trunk facial paresis ( Figure 2D

DISCUSSION
MEC is the most common salivary cancer affecting the parotid gland and comprising approximately 30% of malignant tumors [2]. It usually affects patients from third to ifth decade of life with slight female preponderance [4]. Ionising radiation, therapy with radioactive iodine, cellular phone usage have been considered as speci ic etiological factors for parotid malignancies [2].  Several molecular markers have both diagnostic and prognostic value in MEC. MUC1 is associated with a high histologic grade, high rate of recurrence, metastasis, and short disease-free interval [5]. MUC4, on the other hand, is expressed in low-grade MEC and is associated with a low recurrence rate and a long disease-free interval. In addition, the t(11;19) chromosomal translocation seems to be speci ic to MEC and predicts a better prognosis. CRTC1/MAML2 translocation imparts a better prognosis even when found in high-grade MEC tumors. Epidermal growth factor receptor (EGFR) is also expressed in approximately two-thirds of MECs15 and may be associated with higher grade irrespective of MAML2 fusion status [2,6].
MEC of the parotid gland characteristically present as a painless solitary preauricular mass approximately 2 to 3 cm in diameter at initial discovery. Pain, rapid growth rate, skin involvement, pain, facial tics or weakness, trismus, local soft tissue or bone invasion, and enlarged cervical lymph nodes involvement can be seen with high grade malignant lesions. Pain may be associated with perineural invasion and occurs in up to 40% of malignant tumors. 25% of malignant parotid tumors can involve facial nerve indicating a worse disease outcome. Long-standing parotid gland masses may compress the facial nerves and cause demyelination in the nerve, which in turn may cause spasms in the facial muscles [2,7]. Without pain or facial weakness, the usual diagnosis will be of pleomorphic adenoma and this may result in under treatment when one is not guided by pathological indings of frozen-section analysis. Imaging is required when there is larger and deeper tumors with limited mobility and/or suspected malignancy. Both computed tomography (CT) and magnetic resonance imaging (MRI) are complementary to each other. CT scans are ideal for neck nodes and bony involvement; whereas MRI is better at assessing parapharyngeal space (PPS) involvement and perineural invasion. In dynamic contrast enhancement MRI, malignant salivary gland tumors typically show rapid enhancement and slow washout of the contrast agent. In diffusion-weighted MRI, the apparent diffusion coef icient of malignant tumors is generally lower than that of benign tumors. Ultrasound though not informative as CT or MRI scans; it is most useful in assisting image-guided needle biopsies. Positron Emission Tomography lacks speci icity for malignancy because benign tumors may also have luorodeoxyglucose (FDG) avidity. PET-CT may be useful in assessing regional and distant metastases in the patient with a biopsy-proven malignancy [2,8].
FNAC with a diagnostic accuracy of 79% is most useful in distinguishing between primary salivary tumors and non-neoplastic in lammatory or infectious processes, lymphoma, and metastases from other nonsalivary primary sites [9]. Due to high falsenegative rate of immunohistochemical stains, it can't be used as a reliable method for differentiating between benign and malignant tumors [10]. An incisional biopsy should never be performed on an indeterminate FNA because this may place the facial nerve at risk and increase the risk of recurrence. Instead, an ultrasound-guided core needle biopsy is an alternative safe option for tissue sampling and enhanced diagnostic accuracy [11]. Surgery (super icial or total parotidectomy) with negative surgical margins is the mainstay of treatment for malignant salivary gland tumors. Every effort should be made to preserve facial nerve when it is not directly invaded by tumor; however, the surgeon should be prepared to perform a total parotidectomy that may y extend into the temporal bone to allow for a proximal negative margin resection of the facial nerve if involved. Intraoperative frozen section helps de ine histology and guides surgical execution [2,12].
The optimal extent of a neck dissection in N0 cases is unclear. Supraomohyoid neck dissection addresses the most at-risk nodes in levels II and III. Routine sampling of the level II and III lymph nodes improves staging and helps decide the extent of neck dissection to perform. Alternatively, elective neck radiation may be given; however, the performance of elective neck radiation versus elective neck dissection in management of the N0 neck remains controversial [2,13].
Prognosis is largely based on age, clinical stage, and grade. A lack of consistency among grading systems has led to a discrepancy in reports on prognosis for intermediategrade MEC. This discrepancy can be explained by the use of multiple grading systems, including the Armed Forces Institute of Pathology (AFIP) system, Brandwein system, and the Modi ied-Healy classi ication [14]. Chen and colleagues found that the Brandwein grading system predicted low-grade behaviour in intermediate-grade MEC [15]; however, Aro and colleagues used the AFIP grading system and suggested intermediate-grade MEC be treated like high-grade tumors [15,16]. Overall prognosis of MEC is favourable with a 5-year overall survival of 79% but depends upon grade [2].

CONSENT
Informed written consent was obtained from the patient for publication of the images.