口腔病理科

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原文題目(出處): Lymphadenoma of parotid gland: Two additional cases and a literature review

原文作者姓名: Irving Dardick, , M. Jane Thomas

通訊作者學校: University of Toronto and University of Ottawa

報告者姓名(組別): Int.J 組 魏郁芯

報告日期: 2008/05/12

內文:

Introduction

1. A lymphoid component is the norm for salivary gland lesions such as Warthin’s tumor, sebaceous lymphadenoma and ca, lymphoepithelial cyst, and lymphoepithelial ca.

2. Tumor-associated lymphoid stroma also occurs in acinic cell ca, mucoepidermoid ca, oncocytoma, oncocytic ca, primary SCC, and cystadenocarcinoma.

3. Lymphadenoma represents a relatively recent addition to the group of salivary gland lesions with a prominent tumor-associated lymphoid stroma (with perhaps 9 cases reported or illustrated in journals and texts)

4. Histological - well-defined

- encapsulated

- a predominant lymphoid background, within which most often are embedded solid nondescript or squamous epithelial nests (occasionally, the epithelium is glandular, mixed solid/glandular, or cystic)

5. In all of the cases

- What distinguishes these lesions from sebaceous lymphadenoma→ absence of sebaceous differentiation

- The arrangement and cellular makeup of the epithelium does not resemble any of the usual benign or malignant salivary gland tumors

Material and Methods

1. Case 1 had been recently accessioned as a surgical pathology specimen in the Department of Laboratory Medicine at the Ottawa Hospital, Ottawa, Ontario

2. Case 2, which in 1981 had originally been thought to represent a basal cell adenoma with extensive lymphocytic infiltrate, was retrieved from the files of the Canadian Reference Centre for Cancer Pathology, University of Ottawa, Ottawa, Ontario.

Case Reports Case 1

- A 45-year-old man appeared with a right parotid mass approximately 2 cm in diameter. There was no cervical lymphadenopathy. The excised tumor was well defined and separated from the parotid gland by a capsule of variable thickness, below which there was no evidence of lymphatic sinusoids.

- Histologically, the main feature was a dense lymphatic infiltrate that tended to obscure an isolated

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epithelial component (Fig. 1, A, B).

The latter consisted of irregularly sized and shaped sheets of tumor cells and collections of ductlike glandular structures. (Fig. 1, C, D)

The epithelial component showed no evidence of cytological or nuclear abnormalities and a lack of mitotic activity (Fig. 1, C, D).

A few foci of collagenous and chondroid matrix, as well as epithelial nests with prominent basement membranes, were evident (Fig. 3, A, B).

Immunohistochemistry for cytokeratins (AE1/AE3) confirmed the glandular differentiation of the epithelial portion of this tumor (Fig. 2, A, B).

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There was no evidence of recurrence at 6-months follow-up.

Case 2

- The patient was a 52-year-old male with a 6-month history of a painless mass in the right parotid gland. A discrete, fleshy mass 20 mm in diameter was subsequently resected, together with a portion of a normal parotid gland.

- Histologically, the lymphocytic component of this well-defined tumor nodule tended to obscure the epithelial component (Fig. 4, A). A fibrotic capsule, lacking evidence for a subcapsular sinus, enclosed the tumor (Fig. 4, B).

- Scattered among the lymphocytes were numerous, discrete, relatively small round to irregularly shaped nests of epithelial cells (Fig.4, B, C).

Tumor cells were polygonal to irregular in shape, with round-to-oval shaped nuclei and small-to

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moderately sized nucleoli; mitotic figures were absent (Fig. 4, D).

Glandular differentiation was absent (Fig. 4, B-D). Primarily small mature lymphocytes, with occasional plasma cells and germinal centers, separated the epithelial tumor cells (Fig. 4, B-D).

- The patient was well 3 years after surgical removal, with no evidence of local recurrence or metastases.

DISCUSSION

1. In this class of adenoma with tumor-associated lymphoid proliferation (i.e., lymphadenoma), the growth pattern of the epithelial component generally lacks resemblance to other benign salivary gland tumors such as pleomorphic adenoma, basal cell adenoma, canalicular adenoma, or myoepithelioma.

2. Basic diagnostic criteria for lymphadenoma (Table 1) - No sebaceous differentiation

- Nononcocytic epithelium

- Predominant lymphocytic component with or without germinal centers (may be plasma cells) - Solid, glandular, or cystic epithelial nests

- Well-defined tumor mass with a lack of nodal capsule or subcapsular sinusoids 3. Pleomorphic adenoma

→ A few foci of chondroid differentiation together with the ductal elements and associated neoplastic myoepithelial cells (particularly evident with immunohistochemistry), made cellular pleomorphic adenoma a consideration.

→ With lymphocytic stroma is said to be extremely rare in pleomorphic adenoma 4. Differential diagnoses for lymphadenoma (Table 2)

- Metastatic carcinoma

→ Lack of invasive tumor features

→ No involvement to intraglandular lymph node

→ The absence of subcapsular sinusoids and nuclear and cellular atypia(no increased mitotic activity)

- Mucoepidermoid carcinoma with lymphoid stroma

→ Lack the goblet and intermediate cell lining epithelium

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→ Lack the extravasation of mucus and invasive tendencies - Acinic cell carcinoma with lymphoid stroma

→ The epithelial component of lymphadenoma does not demonstrate the microcystic and follicular growth patterns

→ No acinar cell differentiation with the granular cytoplasm

→ Primary mucoepidermoid and acinic cell carcinomas arising in intraparotid lymph node - Sebaceous lymphadenoma and lymphadenocarcinoma

→ No sebaceous differentiation

→ “nonsebaceous lymphadenoma”

- Warthin’s tumor

→ the absence of both a bilayered oncocytic epithelium and a papillary growth pattern - Myoepithelial sialadenitis

- Benign lymphoepithelial cyst and AIDS-related lymphoepithelial cyst - Lymphoepithelial carcinoma

- Malignant lymphoma

- Papillary cystadenocarcinoma with lymphoid stroma - Primary squamous cell carcinoma with lymphoid stroma - Primary salivary gland tumors arising within a lymph node

題號 題目

1 Which descriptions about mixed tumor (pleomorphic adenoma) is relatively debatable?

(A) The most common salivary tumor (B) Frequently occur in parotid gland (C) Lymphocytic stroma never exists (D) Encapsulation may be incomplete

答案(C) 出處:ORAL & MAXILLOFACIAL PATHOLOCY 2nd EDITION BY Neville Damm, Allen Bouquot p411~p413

題號 題目

2 Which is not the difference between lymphadenoma and mixed tumor?

(A) The frequent components of stroma (B) The growth pattern of epithelial cells (C) The gender predilection

(D) None of above

答案(D) 出處:

1. ORAL & MAXILLOFACIAL PATHOLOCY 2nd EDITION by Neville Damm, Allen Bouquot p411~p413

2. Lymphadenoma of the salivary gland: a rare tumour by N B Musthyala, S E Low and R H Seneviratne, J Clin Pathol 2004;57:1007–1008

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