Carcinoma ex Pleomorphic Adenoma on Right Parotid Gland: A Case Report. School of Dentistry, Kyungpook National University

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1 Korean Journal of Oral and Maxillofacial Pathology 2017;41(4): ISSN: (Print); (Online) Available online at 우측이하선에서발생한다형선종유래암종 장성백 1), 김도형 1), 이성탁 1), 권대근 1), 신홍인 2), 최소영 2) 1) 경북대학교치의학전문대학원구강악안면외과학교실, 2) 구강병리학교실 <Abstract> Carcinoma ex Pleomorphic Adenoma on Right Parotid Gland: A Case Report Seong-Baek Jang 1), Do-Hyoung Kim 1), Sung-Tak Lee 1), Tae-Geon Kwon 1), Hong-In Shin 2), So-Young Choi 1)* 1) Department of Oral & Maxillofacial Surgery, 2) Department of Oral Pathology, School of Dentistry, Kyungpook National University Carcinoma ex pleomorphic adenoma (Ca ex PA) is an uncommon malignant tumor. It is an aggressive salivary carcinoma, arising from a primary or recurrent benign pleomorphic adenoma (PA). The most common clinical presentation of Ca ex PA is a firm mass in the parotid gland. Here we report a case of Ca ex PA, arising from a recurrent benign PA in the right parotid gland, in a 70-year old female patient. The lesion was first diagnosed as a PA and a superficial parotidectomy was performed. Re-operation was performed for recurrent PA. The second recurrence was diagnosed as Ca ex PA. Key words : Carcinoma ex pleomorphic adenoma, Pleomorphic adenoma, Parotid gland Ⅰ. INTRODUCTION Carcinoma ex pleomorphic adenoma (Ca ex PA) is an uncommon malignant tumor. Ca ex PA arises from a primary or recurrent benign pleomorphic adenoma 1,2). Ca ex PA is a rare disease, with a prevalence rate of 5.6 cases per 100,000 malignant neoplasms. The yearly incidence rate is 0.17 tumors per 1 million persons 3). Around 25% of pleomorphic adenomas undergo malignant transformation 4). Malignant mixed tumors can be divided into three different types: (1) carcinoma ex pleomorphic adenoma; (2) true malignant mixed tumor (carcinosarcoma); (3) metastasizing mixed tumor. Ca ex PA is the most common malignant form 5). In this study, we investigate a case of malignant transformation of a pleomorphic adenoma into a Ca ex PA, following two surgical operations to remove the tumor. Ⅱ. CASE REPORT RESULTS * Correspondence: So-Young Choi, Department of Oral & Maxillofacial Surgery, School of Dentistry, Kyungpook National University Tel: dentalchoi@knu.ac.kr ORCID : Received: Jul ; Revised: Jul ; Accepted: Aug A 70-year-old female patient, with no unusual medical history, presented to our department with swelling, pain and palpations at the root of her right ear, which had begun

2 observed. For a more accurate diagnosis, sonography and one month previously. On the first examination, swelling of the right parotid fine needle aspiration (FNA) were performed. The gland area was observed. Three-dimensional (3D) neck sonography reading indicated a hypoechoic mass in the computed tomography (CT) was performed. The CT result right parotid. FNA results suggested the presence of a showed a well-defined soft tissue mass, measuring 2 x 1.5 benign mixed tumor. Based on these readings, the mass cm, on the right parotid gland. Bony invasion was not was provisionally diagnosed as pleomorphic adenoma. The Fig 1. (A, B): Computed tomography showed a well-encapsulated oval mass (axial and coronal views). (C): An intraoperative view showed the facial nerve which allowed the surgeon to prevent nerve damage. (D): Gross specimen. (E): A low-power photomicrograph showed a well-defined mass (H&E, 45). (F): The tumor was composed of sheets of myoepithelial cells (H&E, 100). 190

3 patient re-visited the clinic four months later. A 3D neck CT was taken showing that the mass had enlarged (Fig. 1A, B). The patient underwent a superficial parotidectomy (Fig. 1C, D). Microscopic examination showed the presence of a pleomorphic adenoma with a well-circumscribed and encapsulated tumor mass. Plasmacytoid myoepithelial cells in a myxoid stroma and ductal structures with an associated mycomatous background were also observed (Fig. 1E, F). At the 11-month follow-up, a mass measuring 1 cm was observed at the right mandibular angle. A CT scan indicated a relatively well-circumscribed mass on the lateral and anterior part of the right masseter muscle (Fig. 2A, B). A Fig 2. (A, B): Computed tomography showed a heterogeneous mass (axial and coronal views). (C): Intraoperative view. (D): Gross specimen. (E): A low-power photomicrograph showed a well-encapsulated mass (H&E, 45). (F): The tumor was composed of islands or sheets of myoepithelial cells with a myxomatous background (H&E, 100). 191

4 recurrent pleomorphic adenoma was diagnosed and a total parotidectomy was performed. The postoperative tissue specimen revealed a relatively well-circumscribed mass (Fig. 2C, D). Tissue biopsy showed the presence of a pleomorphic adenoma (Fig. 2E, F). Six months after the second operation, a new mass was found on the lower edge of the patient s right mandibular angle. FNA was conducted and indicated the presence of Fig 3. (A, B): Computed tomography showed a large heterogeneous mass (axial & coronal views). (C): A large mass was visualized in the parotid and submandibular area. (D): PET-CT showed an intense uptake of 18F-FGD in the right parotid & submandibular area and in the left side of the lung. (E): Medium-power photomicrograph imaging showed a high cellularity. The cells displayed large, pleomorphic and hyperchromatic nuclei (H&E, 200). (F): A high-power photomicrograph showed pleomorphic myoepithelial cells with increased mitosis and hyperchromatism (H&E, 400). 192

5 a benign salivary gland neoplasm. Further surgery was considered; however, the patient was not followed up for two years, due to her personal circumstances. Two years later, the patient presented with a large mass located to the posterior of the right ear at the right mandibular lower edge. A CT scan showed a large lesion across the entire right parotid gland. The lesion had invaded the upper portion of the mandible and had abutted the right internal carotid artery (Fig. 3A, B). A malignant transformation was confirmed and positron emission tomography (PET)-CT showed a lung metastasis (Fig. 3C, D). A tissue biopsy demonstrated a high tissue malignancy rate and showed the presence of a clear cell tumor (of the spindle cell subtype), with an increase in tissue shape diversity and atypical mitosis (Fig 3E, F). Based on clinical information, radiological scans and the result of the tissue biopsy, the patient was diagnosed with Ca Ex PA. A salvage operation was considered; however, the patient did not re-attend the clinic. Ⅲ. DISCUSSION Pleomorphic adenoma (PA) is the most common benign salivary gland tumor 6). PA arises predominantly from the parotid gland, though may arise from the minor salivary glands and the seromucinous glands of other organs (e.g. the oral cavity, trachea and nasal cavity) 7). There is a strong correlation between early surgical removal of PA and a reduced recurrence rate 8). One study reported that following parotidectomy, PA has the lowest tumor recurrence rate 9,10). PA recurs in around 11~18% of cases. A second recurrence occurs in around 20~40% of cases, following which the rate is around 20% 11,12). In this study, we witnessed a rare case of a patient with two recurrences of a PA, which at the second recurrence had transformed into a Ca ex PA. Malignant transformation of PA typically presents as a Ca ex PA, an uncommon and aggressive salivary malignancy, which is hard to diagnose and cure. Ca ex PA has a high propensity for metastatic spread. The malignant mixed tumor area is often small and extensive hyalinization may occur. These factors lead to the high mortality rate seen in the disease 13). The most common clinical presentation of Ca ex PA is a mass in the parotid gland. A study reported the presence of a parotid mass in 86% of cases of Ca ex PA 2,13). The majority of Ca ex PA lesions are invasive and have ill-defined borders 14). Pain usually arises from the local extension of the neoplasm into adjacent soft and hard tissues. When Ca ex PA involves the facial nerve, the patient presents with facial nerve paresis or palsy 13,15). The patient in this study had a large mass on the parotid gland and presented with mild facial nerve paresis after the first and second operations. A well-constructed clinical history and a pathological biopsy are necessary for making the final diagnosis. Additionally, FNA, sonography, CT scanning, and magnetic resonance imaging can be used for making a diagnosis 1). Ca ex PA occasionally arises as a mixture of PA and carcinoma. Benign mixed components may exist close to the malignant area and metastasis can occur to the benign region. However, sometimes it is not easy to FNA to diagnosis Ca ex PA. There is even a report claiming that the sensitivity is less than 30% 17). Due to the difficulties in diagnosing a mixed sample, comprehensive testing should be performed to allow for an accurate diagnosis. A rapid growth spurt, in a slow growing parotid mass, should alert the clinician to the possibility of a Ca ex PA. Ca ex PA should be diagnosed differentially with other benign and malignant salivary gland tumors and with subtypes of malignant mixed tumor 16). Treatment for Ca ex PA may involve a parotidectomy. 193

6 Superficial parotidectomy is used for intracapsular or minimally invasive Ca ex PA localized to the superficial lobe of the parotid gland. Total parotidectomy is used when both the deep and superficial lobes of the parotid are involved. In all cases, every attempt should be made to preserve the facial nerve 2,13). Here we initially performed a superficial parotidectomy Following recurrence of the mass we performed a total parotidectomy. Following this, a second recurrence occurred and the malignant transformation of PA into Ca ex PA was observed. Ca ex PA is an uncommon malignant tumor, arising from a primary or recurrent, benign pleomorphic adenoma. Here, we reported a rare case of a PA at the second recurrence had transformed into a Ca ex PA. Clinicians should be aware of the potential malignant transformation of PA and understand the need for regular follow-ups. Furthermore, clinicians should always assess for tumor recurrences and long-distance metastases, with regular clinical and radiological follow-ups. REFERENCES 1. Antony J, Gopalan V, Smith RA: Carcinoma ex pleomorphic adenoma: A comprehensive review of clinical, pathological and molecular data. Head Neck Pathol 2012;6: Nouraei SA, Hope KL, Kelly CG: Carcinoma ex benign pleomorphic adenoma of the parotid gland. Plast Reconstr Surg 2005;116: Gnepp DR: Malignant mixed tumors of the salivary glands: a review. Pathol Annu 1993;28: Shoor Hitesh, Pai Keerthilatha M, Vineetha R: Myoepithelial Carcinoma Arising In Pleomorphic Adenoma of Palatal Minor Salivary Gland: Report of a Rare Case. OHDM 2016;15: Lewis JE, Olsen KD, Sebo TJ: Carcinoma ex pleomorphic adenoma: pathologic analysis of 73 cases. Hum Pathol 2001;32: Wittekindt C, Streubel K, Arnold G: Recurrent pleomorphic adenoma of the parotid gland: Analysis of 108 consecutive patients. Head Neck 2007;29: Cimino-Msathews A, Lin BM, Chang SS: Carcinoma ex pleomorphic adenoma of the nasal cavity. Head Neck Pathol 2011;5: Woods JE, Chong GC, Beahrs OH: Experience with 1,360 primary parotid tumors. Am J Surg 1975;130: Guntinas-Lichius O, Kick C, Klussmann JP: Pleomorphic adenoma of the parotid gland: a 13-year experience of consequent management by lateral or total parotidectomy. Eur Arch Otorhinolaryngol 2004;261: Maynard JD: Management of pleomorphic adenoma of the parotid. Br J Surg 1988;75: Glas AS, Vermey A, Hollema H: Surgical treatment of recurrent pleomorphic adenoma of the parotid gland: a clinical analysis of 52 patients. Head Neck 2001;23: Renehan A, Gleave EN, McGurk M: An analysis of the treatment of 114 patients with recurrent pleomorphic adenomas of the parotid gland. Am J Surg 1996;172: Olsen KD, Lewis JE: Carcinoma ex pleomorphic adenoma: a Clinicopathologic review. Head Neck 2001;23: Raine C, Saliba K, Chippindale AJ: Radiological imaging in primary parotid malignancy. Br J Plast Surg 2003;56: Zbären P, Zbären S, Caversaco MD: Carcinoma ex pleomorphic adenoma: diagnostic difficulty and outcome. Otolaryngol Head Neck Surg 2008;138: Di Palma S, Lambros MB, Savage K: Oncocytic change in pleomorphic adenoma: molecular evidence in support of an origin in neoplastic cells. J Clin Pathol 2007;60: Chen AM, Garcia J, Bucci MK: The role of post operative radiation therapy in carcinoma ex pleomorphic adenoma of the parotid gland. Int J Radiat Oncol Biol Phys 2007;67: