**3. Salivary gland tumors**

The common salivary gland tumors needing IHC are:


**•** Nuclear p63 expression is common in squamous cell carcinomas but is not specific

**•** Over expression of p53 may be linked to response to radiation and/or chemotherapy

nodes (Figure 1).

**2.2. Mucosal melanoma**

*2.2.2. Immunohistochemical stains*

are negative (Figure 2). [6-13]

*2.2.1. Definition*

carcinoma (HPV associated). [1-5]

310 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

**Figure 1.** a) Squamous cell carcinoma (H&E). b) Cytokeratin stains in SCC.

melanocytes and demonstrating melanocytic differentiation.

**Figure 2.** a) Mucosal melanoma (H&E) b) IHC staining for HMB-45

**•** Cytokeratin stains may help detect subtle metastatic foci especially in post-treatment lymph

**•** p16 positive: strong and diffuse nuclear and cytoplasmic expression in oropharyngeal

a) b)

Malignant mucosal melanoma (MMM) is a neural crest–derived neoplasm originating from

S100 protein, Melan A, HMB45, tyrosinase, vimentin are positive, Keratin and muscle markers

a) b)


### **3.1. Pleomorphic adenoma**

#### *3.1.1. Definition*

A benign neoplasm composed of ductal epithelial and myoepithelial cells set within a mesenchymal stroma.

## *3.1.2. Immunohistochemical stains*

Cytokeratin cocktail, S100 protein, SMA, p63, calponin, MSA, GFAP, and CD10 reactive the cells are highlighted by a mixture of epithelial and myoepithelial markers that include AE1/ AE3, CK5/6, CK7, and CK14; S-100 protein; p63; SMA; calponin; and GFAP. (Figure 3). [14-16]

#### **3.2. Basal cell adenoma**

### *3.2.1. Definition*

Basal cell adenoma is a benign salivary gland epithelial neoplasm composed of a proliferation of small basaloid cells in solid, tubular, trabecular, or membranous patterns. (Figure 4).

#### *3.2.2. Immunohistochemical stains*

Immunohistochemical Inner luminal cells: cytokeratin cocktail, CK7, and CD117 Peripheral basaloid cellS\_100 protein, p63, SMA, and MSA [17 -19]

**Figure 3.** a) Pleomorphic adenoma shows a mixture of myoepithelial cells and isolated duct-tubular structures b) S-100 protein in the myoepithelial cells.

**Figure 4.** a) Basal cell adenoma, trabecular type b) p63 highlights the basal cells

#### **3.3. Canalicular adenoma**

#### *3.3.1. Definition*

Canalicular adenoma is a benign epithelial salivary gland neoplasm characterized by chains of columnar cells and preference for the minor salivary glands.

#### *3.3.2. Immunohistochemical stains*

Cytokeratin and S100 protein reactive GFAP is reactive at the tumor/connective tissue interface (Figure 5.) [17-23].

#### **3.4. Oncocytoma**

#### *3.4.1. Definition*

Oncocytoma (oncocytic adenoma) is a putative neoplastic proliferation of oncocytically altered cells.

**Figure 5.** a) Canalicular adenoma, b) GFAP staining is positive

### *3.4.2. Immunohistochemical stains)*

Cytokeratin, p63, and PTAH reactive (Figure 6) [17- 19, 21, 22]

**Figure 6.** a) Oncocytes are Cytokeratin, highly positive polygonal cells with abundant granular eosinophilic cytoplasm and round, centrally placed nuclei, with or without nucleoli. b) p63 reactive.

#### **3.5. Papillary cystadenoma lymphomatosum (Warthin's tumor)**

#### *3.5.1. Definition*

a) b)

a) b)

**Figure 3.** a) Pleomorphic adenoma shows a mixture of myoepithelial cells and isolated duct-tubular structures b) S-100

Canalicular adenoma is a benign epithelial salivary gland neoplasm characterized by chains

Cytokeratin and S100 protein reactive GFAP is reactive at the tumor/connective tissue interface

Oncocytoma (oncocytic adenoma) is a putative neoplastic proliferation of oncocytically altered

**Figure 4.** a) Basal cell adenoma, trabecular type b) p63 highlights the basal cells

of columnar cells and preference for the minor salivary glands.

**3.3. Canalicular adenoma**

protein in the myoepithelial cells.

312 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

*3.3.2. Immunohistochemical stains*

*3.3.1. Definition*

(Figure 5.) [17-23].

**3.4. Oncocytoma**

*3.4.1. Definition*

cells.

Warthin's tumor is a relatively common lesion composed of a double layer of oncocytic and cystic architectural pattern cells, and a dense lymphoid epithelium in a papillary stroma. (Figure7)

#### *3.5.2. Immunohistochemical stains*

Epithelial component keratin reactive Lymphoid component reactive with B- and T-cell markers [17- 19]

**Figure 7.** a) Papillary-cystic tumor associated with a dense lymphoid stroma. b) KI 67 positive B- cell component.

#### **3.6. Sebaceous adenoma / lymphadenoma**

#### *3.6.1. Definition*

Sebaceous adenoma is a benign epithelial neoplasm composed of proliferating, incompletely differentiated sebaceous glands. Sebaceous lymph adenoma is a rare variant in which the epithelial proliferation is supported by a dense lymphoid stroma and possibly arises from entrapped salivary gland tissue within intraparotid or periparotid lymph nodes (Figure 8).

#### *3.6.2. Immunohistochemical stains*

Immunohistochemistry can be used to confirm the sebaceous differentiation (such as with CD15, androgen receptor, or EMA Epithelial component is cytokeratin and is EMA reactive) [17-19]

**Figure 8.** a) Sebaceous lymphadenoma b) EMA highlights the sebocytes
