原文題目

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口腔病理科 On-Line KMU Student Bulletin

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原文題目(出處)： Central mucoepidermoid carcinoma, a case report with molecular analysis of the TORC1/MAML2 gene fusion Head and Neck Pathol 2010;4:261-4

原文作者姓名： Haseeb Ahmed Khan, Asi Loya, Rafay Azhar, Nasir Ud Din, Diana Bell

通訊作者學校： Department of Pathology, Shaukat Khanum Memorial Cancer Hospital & Research Center, Johar Town, Lahore, Pakistan

報告者姓名(組別)：吳佳蓁 (Intern E 組)

報告日期： 99 /12/13

內文：

1. Abstract

(1) Mucoepidermoid carcinoma is the most common salivary gland malignancy i. Majorities arise in parotid and minor salivary glands

ii. Rarely develop intraosseously

(2) This case report is an example of intraosseous mucoepidermoid carcinoma with positive TORC1/MAML2 gene fusion transcript and discusses the clinical implications

2. Introduction

(1) Mucoepidermoid carcinoma (MEC) is the most common malignant tumor of salivary glands.

i. Intraosseous development is rare: difficult to diagnose and manage.

ii. Histogenesis of MEC is uncertain, but an origin from ectopic salivary tissue or metaplastic transformation of odontogenic epithelium has been proposed.

(2) MEC occurs at relatively younge age i. More female than male patients

ii. Most common symptoms: pain and swelling

iii. Radiologically: unilocular or multilocular well-circumscribed radiolucency

3. Case report

(1) Patient: 20 year old male with a history of pain, swelling, and discharge in the left mandible of one and a half years duration.

(2) CT scan: circumscribed intraosseous lytic lesion with solid and cystic components involving ramus and part of the left mandible body

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i. Lesion was displacing unerrupted 3^rd molar thickening of overlying bone and soft tissue

ii. Differential diagnosis (at this stage): odontogenic keratocyst and ameloblastoma

(3) Incisional biopsy: consisted of multiple hemorrhagic soft tissue fragments i. Microscopic examination: epithelial lined cyst wall with infiltrating

nests of squamoid and mucin producing cells

ii. Presence of mucin was confirmed by mucicarmine stain

iii. Cytokeratin AE1/AE3 positively proved epithelial nature of cells iv. Diagnosis of mucoepidermoid carcinoma was made

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(4) RNA was extracted from the tissue

i. Positive control: RNA from MEC that had been previously identified as having the transcript

ii. Negative control: RNA from MEC lacking the transcript

iii. Gel electrophroesis was performed and visualized with ethidium bromide and staining under UV light

iv. The CRTC1/MAML2 fusion transcript was detected in the mucoepidermoid carcinoma.

4. Discussion

(1) The detection of TORC1/MAML2 fusion gene in this case is the first documentation of this event in these tumors

(2) Studies of mucoepidermoid carcinomas in salivary glands and at unconventional sites (breast, cervix, lung, thyroid, and skin) have detected the same fusion gene.

(3) TORC1/MAML2 fusion gene results from: translocation of long arm of chromosome 11 with the long arm of chromosome 19, where exon 1 of the TORC1 gene and exons 2-5 of the MAML2 are linked

i. Leads to altered Notch signaling tumorigenesis (4) Recent data suggests that this fusion in MEC is fairly common

i. Can help as a diagnostic marker especially in poorly differentiated tumors

(5) Prognosis of patients with intraosseous MEC is good, especially for patients with radiologically cystic or rarefying type lesion.

(6) Studies of salivary MEC with fusion positive have also reported a better survival advantage

(7) Whether similar findings hold true for intraosseous MEC’s must await additional cases and studies with long-term follow up.

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題號題目

1 關於 mucoepidermoid carcinoma (MEC) ,下列敘述何者為非?

(A) MEC 的好發年齡是 10 歲以下的病患 (B) MEC 較常發生在女性

(C) MEC 是最常見的惡性唾液腺腫瘤 (D) MEC 在 parotid gland 最常見

答案(A) 出處：Oral & Maxillofacial Pathology, Second Edition. p.420

題號題目

2 何者是 intraosseous mucoepidermoid carcinoma 最常見的好發部位?

(A) 上顎前牙 (B) 上顎後牙 (C) 下顎前牙 (D) 下顎後牙

答案(D) 出處：Oral & Maxillofacial Pathology, Second Edition. p.422