原文題目

口腔病理科 On-Line KMU Student Bulletin

原文題目(出處)： Imaging features of myoepithelial carcinoma of the mandible with lymph node metastasis. Oral Radiol 2010;

26:29-35 原文作者姓名： Yoshiko Ariji

通訊作者學校： Department of Oral and Maxillofacial Radiology, Aichi-Gakuin University School of Dentistry, 2-11 Suemori-dori, Chikusa-ku, Nagoya 464-8651, Japan

報告者姓名(組別)： Intern C 組 張瑞云

報告日期： 99.10.08

內文：

1. Introduction

 Myoepithelial carcinoma (MEC) is an uncommon tumor which accounts for fewer than 1% of all salivary gland neoplasm.

 Characteristics of myoepithelial carcinoma (MEC):

 Site: parotid gland (70~80%)

 Age: mean age 55 years old

 Sex: slight female predominance

 Cervical lymph node metastasis: 20%

 Prognosis: generally good, but the risk of local recurrence is high (about one-third)

2. Case Report

 General data:

 Age: 57

 Sex: female

 Chief complaint

dull pain over LL molar region for 3 months, swelling for 2 months. The swelling mass increased rapidly in size.

 Oral examination:

12*12 mm elastic-soft, fixed mass in submandibular region, poor healing and bone exposure of extracted socket of 36, 37.

 Biochemical test: high level of alkaline phosphatase.

 Previous treatment: antibiotic prescription and curettage of extracted socket.

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口腔病理科 On-Line KMU Student Bulletin

 A Panoramic radiogram showing the remains of the extracted socket and no marked absorption of the bone trabecula in the left lower molar region.

 CT image showing permeative destruction of the bone trabecula of the left mandible beyond the mandibular canal. The buccal and lingual cortical plates presented with intermittent absorption.

 MR images of the mandible.

 T1-weighted MR image showing a decrease in the signal intensity of the

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口腔病理科 On-Line KMU Student Bulletin

bone marrow in the left lower premolar and molar regions, except for the region in which gauze had been packed into the previously curetted area.

 T2-weighted image showing a slight decrease in the same region.

 T1-weighted image after contrast medium administration showing marked enhancement in the same region. The periosteum was elevated, and a tumor was confirmed outside the buccal and lingual cortical plates

 CT image showing a 30*30 mm, round, well-defined, waterdensity mass with a peripheral soft-tissue-density thin rim.

The submandibular gland was deviated posteriorly by this mass.

 T1-weighted MR image showing low signal intensity.

 T2-weighted MR image showing markedly high signal intensity. A low-intensity capsule was observed around the mass.

3. Diagnosis and Treatment

 Treatment: curettage of mandibular molar region and resection of submandibular tumor.

 Histological findings: spindle-shaped and round-shaped tumor cells formed solid or restiform patterns. The nucleus was variable in size, and demonstrated high mitotic activity and nuclear polymorphism.

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口腔病理科 On-Line KMU Student Bulletin

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 Immunohistochemical findings: positive for cytokeratin, smooth muscle actin, and Vimentin.

 Diagnosis: myoepithelial carcinoma of mandible with metastasis of submandibular lymph node.

4. Discussion

 Could be smooth and well-defined tumors without invasion of the adjacent fat planes, suggesting benign tumors; whereas others have reported poorly circumscribed lobular tumors

 Description of the tumor interface has been reported to differ depending on imaging modality: MRI displays the interface more clearly than CT.

 MEC displays uniform low signal intensity in T1-weighted MR images and moderately high signal intensity in T2-weighted images.

 The high signal intensity in T2-weighted images is consistent with low-grade malignant salivary gland tumors.

 Contrast enhancement suggested a physiologically rich blood supply for the tumor, or highly vascularized characteristics of MEC.

 Low-grade malignant salivary gland tumors are sometimes misdiagnosed as benign tumors preoperatively. Such a situation leads to selection of an inappropriate surgical technique, outcomes of frequent local recurrence, and poor prognosis.

題號 題目

1

(A) Ewing’s sarcoma

(B) Myoepithelial carcinoma (C) Ameloblastoma

(D) Liposarcoma

答案( B ) 出處：Oral &Maxillofacial Pathology 2^nd Edition, P407, 481, 581, 611

題號 題目

2

(A) Pleomorphic adenoma (B) Warthin tumor

(C) Mucoepidemoid carcinoma (D) Myoepithelial carcinoma

答案( A ) 出處：Oral &Maxillofacial Pathology 2^nd Edition, P.410, 415, 421