原文題目(出處)： Myoepithelioma of the upper lip. J Dent Sci 2017;12:98-102 原文作者姓名： Hirohiko Tachibana , Shigeo Ishikawa, Noriaki
Kikuchi,Mitsunori Yamakawa, Yoshioki Hamamoto, Mitsuyoshi Iino
通訊作者學校： Department of Dentistry, Oral and Maxillofacial Plastic and Reconstruction Surgery, Faculty of Medicine, Yamagata University, Yamagata, Japan
報告者姓名(組別)： 郭昱宏 Intern I
報告日期： 2017/04/06
內文：
Introduction
1. 性質：Myoepithelial cells are ectoderm-derived contractile cells that exhibit both epithelial and smooth muscle properties.
2. 位置：Myoepithelial cells in salivary glands and other exocrine organs situated between the basal lamina and the acinar and ductal cells
3. Myoepithelioma ＝> those rare benign tumors composed entirely of
myoepithelioma cells that account for less than 1% of all salivary gland tumors 4. 診斷依據：analysis of the expression of cytoplasmic filaments and ultrastructural
features of these cells is important for identifying the criteria providing a diagnosis of myoepithelioma
5. 好發位置：大部分位於 parotid gland，少部分會來自 submandibular gland &
minor salivary gland。
6. 本篇 case 為一稀少病例，發生位置在上唇區。目前為已報導中的病例中發
現的第六例。
Case report
Age: 56 Sex:Female Location:
Left side of upper lip Chief Complants:
A painless mass on her upper lip that had gradually increased in size over a period of 3 years
Present Illness:
Medical history was noncontributory.
Physical Examination:
A soybean-sized, hard, mobile, and nontender submucosal mass was observed on the left side of her upper lip.
No palpable cervical lymph nodes.
MRI finding:
A 23 mm x 18 mm well-defined, ovoid tumor. The peripheral area of the tumor was uniformly thickly enhanced, while the central area showed a partially cystic structure. No absorption or destruction of the maxillary bone was observed.
Figure 2
(A) T1-weighted magnetic resonance imaging (MRI), showing that the tumor was heterogeneously enhanced.
(B) T2-weighted MRI scan, showing that the tumor had a heterogeneous, predominantly increased signal and internal septa of low signal isointensity.
Operation：
Excision under GA, safe margin:5mm, defect covered by artificial dermis Gross inspection：
The resected tumor had smooth surface an well-circumscribed and encapsulated
The cut surface of the tumor appeared solid, homogeneous,and white in color Microscopically：
The tumor was composed of myoepithelial cells
Figure 3 (A) Photograph showing the tumor covered by a fibrous capsule (40x magnification)
Figure 3 (C) A very small number of nuclear mitoses can be seen (400x magnification). All hematoxylin-eosin stain
Immunohistochemically：
The tumor epithelioid cells were diffusely and strongly immunoreactive for S-100 protein and cytokeratins (AE1/AE3, CAM5.2, and CK7).
Most of the cells were also reactive for both vimentin and calponin.
However, they were negative for alpha-smooth muscle actin and p63 (Fig. 4)
Figure 4 Immunohistochemical findings. The tumor cells are positive for S-100 protein, AE1/AE3, CAM5.2, CK7, vimentin, and calponin. Original magnifications 200x
The proliferative index Ki-67 was about 3% (Fig. 5)
Figure 5 Immunohistochemical finding. The Ki-67 labeling index is about 3%.
Original magnifications 100x
Post-operation：No recurrence over the intervening period of about 4 years
Discussion
The diagnostic term myoepithelioma was first used by Sheldon in 1943
Reclassified as an independent entity in 1991 in the WHO international classification of salivary gland tumors
Myoepithelioma
Sex occurs in both men and women
Age most frequently between 30 and 40 years
of age. Observed over a very wide age range from children to the elderly
Site parotid gland(40%)
palatine glands(21%)
plasmacytoid cell (7.5%), clear cells (2.5%)
(Dardick,1989) Morphologic architecture
a solid pattern with tumor cells growing densely and accompanied by a fibrous stroma
a myxoid pattern with tumor cells growing in an insular, trabecular, and sporadic manner in an abundant myxoid matrix
a reticular pattern with a trabecular structure of tumor cells against a backdrop of myxoid or hyaline matrix
a mixture of these three growth pattern types
60% of myoepithelioma tumors have a solid growth pattern
--> Our case showed about 80% solid pattern and about 20% myxoid pattern On immunostaining
the frequently intensity of positive stained cells varies according to cell type
spindle cell a weak expression of cytokeratin
but a strong expression of alpha-smooth muscle actin
plasmacytoid and epithelioid or epithelial cell
clearly express cytokeratin, but very few express alpha-smooth muscle actin
Clear cell weak expression of both molecules
One cannot reject a diagnosis of myoepithelioma in patients without an extensive expression of alpha-smooth muscle actin
S-100 protein：a high percentage of tumor cells stain positive for this protein --> Our case shows：
(+)：cyto cytokeratins (AE1/AE3, CAM5.2, and CK7), vimentin, calponin, and S-100 protein
(-)：alpha-smooth muscle actin and p63
Histologic examination：a scattered mixture of clear cells and epithelial cells with a myxoid matrix and a clear boundary between the parenchyma and stroma
Stain (-) because the main body of the tumor consisted of epithelioid or epithelial cells that contained few positive smooth muscle cells.
No clear ductal structures or chondroid profile as is seen in pleomorphic adenoma
The cellular morphology was diverse
No sign of separation of the neoplastic myoepithelial cells into the stroma
No cellular atypia was recognized
Ki-67 labeling rate approximately 3%, and growth was localized
Further periodic follow-up must be carried out because a case of recurrence has been reported 24 years after removal of such a tumor(Hisao S,2006)
答案 (A)
出處：Oral and Maxillofacial Pathology, Nevielle, Saunders W. B. Co. 3rd edition., Chap 11 Salivary Gland Pathology ,p478
題號 題目
2
A slowly growing tumor near right parotid gland.No facial nerve palsy nor pain. What's the most possible impression?
(A) Pleomorphic adenoma (B) Mucocele
(C) Sialoithiasis (D) Warthin tumor 答案
(A)
出處：Oral and Maxillofacial Pathology, Nevielle, Saunders W. B. Co. 3rd edition., Chap 11 Salivary Gland Pathology ,p453~p483
