Immunohistochemical (ihc) stains are widely used for diagnosis of tumors. In this chapter we present modern immunohistochemical stains for diagnosing those tumors that cannot be evaluated via common or routine stains such as hematoxylin and eosin.
2. Epithelial tumors
Squamous cell carcinoma (SCC) and malignant melanoma are common epithelial lesions that require IHC.
2.1. Squamous cell carcinoma
SCC is a malignant neoplasm arising from the squamous epithelium of the oral cavity most commonly from the lip, then tongue, floor of mouth, gingiva, palate, and buccal mucosa. Premalignant changes present as white (leukoplakia) or red (erythroplakia) mucosal patches.
2.1.2. Immunohistochemical stains
Squamous carcinomas are nearly always positive for CK.
Common CK expression in squamous carcinomas includes AE1/AE3 and CKs 5, 5/6, 14, and 17.
Nuclear p63 expression is common in squamous cell carcinomas but is not specific
Cytokeratin stains may help detect subtle metastatic foci especially in post-treatment lymph nodes (Figure 1).
Over expression of p53 may be linked to response to radiation and/or chemotherapy
p16 positive: strong and diffuse nuclear and cytoplasmic expression in oropharyngeal carcinoma (HPV associated). [1-5]
2.2. Mucosal melanoma
Malignant mucosal melanoma (MMM) is a neural crest–derived neoplasm originating from melanocytes and demonstrating melanocytic differentiation.
3. Salivary gland tumors
The common salivary gland tumors needing IHC are:
BASAL CELL ADENOMA
PAPILLARY CYSTADENOMA LYMPHOMATOSUM (WARTHIN TUMOR(
ADENOID CYSTIC CARCINOMA
POLYMORPHOUS LOW-GRADE ADENOCARCINOMA
CLEAR CELL CARCINOMA
ACINIC CELL CARCINOMA
3.1. Pleomorphic adenoma
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
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]
3.3. Canalicular adenoma
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].
Oncocytoma (oncocytic adenoma) is a putative neoplastic proliferation of oncocytically altered cells.
3.4.2. Immunohistochemical stains)
Cytokeratin, p63, and PTAH reactive (Figure 6) [17- 19, 21, 22]
3.5. Papillary cystadenoma lymphomatosum (Warthin’s tumor)
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]
3.6. Sebaceous adenoma / lymphadenoma
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]
3.7. Mucoepidermoid carcinoma
A malignant glandular epithelial neoplasm characterized by mucus, intermediate, and epidermoid cells. This common salivary gland malignancy represents between 2% and 16% of all salivary gland tumors and up to one third of malignant salivary gland tumors.
3.8. Immunohistochemical stains
Intermediate and epidermoid cells are immunoreactive for cytokeratin and frequently EMA Three cell populations can generally be seen in MEC- epidermoid cells, mucous cells, and intermediate cells— variably set within a cystic background (Figure 9).
CK5/6, Ki-67, and p63 nuclear expression may help in the differential diagnosis. [23, 24]
3.9. Adenoid cystic carcinoma
Adenoid cystic carcinoma accounts for 10% of all malignant salivary gland tumors. ACC is cribriform and has two prominent growth patterns: Tubular, and solid, and it is composed of epithelial and myoepithelial cells (Figure 10).
3.9.2. Immunohistochemical stains
Pseudocysts are positive for PAS, Alcian blue, laminin, and type IV collagen Epithelial cells are positive for low-molecular-weight keratins, EMA, and CD117 Myoepithelial cells are positive with calponin, SMA, S100 protein, and p63. [25 – 32].
Polymorphous low-grade adenocarcinoma.
This is a malignant epithelial tumor characterized by an infiltrative growth of cytologically uniform cells (“low-grade”) arranged in architecturally diverse patterns (polymorphous), slowly growing tumor that exclusively affects the minor salivary glands, most often of the palate (Figure 11).
3.10. Epithelial-myoepithelial carcinoma
Epithelial-myoepithelial carcinoma is a low-grade, malignant, biphasic salivary tumor that comprises 1% to 2% of all salivary neoplasms, the majority of which develop in the parotid gland. It is a malignant neoplasm with biphasic duct-like structures composed of an inner layer of duct lining, epithelium-type cells and an outer layer of clear, myoepithelial-type cells (Figure 12).
3.11. Clear cell Carcinoma
Many salivary and nonsalivary tumors contain clear cells. Among these are mucoepidermoid carcinoma, acinic cell carcinoma, oncocytoma, renal cell carcinoma, myoepithelioma, and clear cell odontogenic carcinoma.
3.11.2. Immunohistochemical stains
The neoplastic cells are positive with AE1/AE3, CAM5. 2, CK7, EMA, and p63; cells are negative with S-100 protein, calponin, actins, and GFAP (Figure 13). They are usually negative for myoepithelial markers that include S-100 protein, MSA, SMA, SMMHC, calponin, and GFAP and are also negative for CD10, CK20, vimentin, desmin, RCC, CA9, and Pax-2 see). [35-37]
3.12. Acinic cell carcinoma
A malignant epithelial neoplasm demonstrating serous acinar cell differentiation with cytoplasmic zymogen secretory granules (Figure 14).
3.12.2. Immunohistochemical stains
PAS-positive, diastase-resistant zymogen granules. Acinic cells may stain positively for amylase, transferrin, lactoferrin, CEA, VIP, and others. About 10% show some positivity for S100 protein. [38, 39]
4. Soft tissue tumors
The most common soft tissue tumors needing IHC are:
Lobular capillary hemangioma
Granular Cell Tumor
4.1. Lobular capillary hemangioma
Lobular capillary hemangioma previously commonly referred to as “pyogenic granuloma, ” is a reactive soft tissue growth with a predilection for the oral cavity that is histologically characterized by a lobular arrangement (Figure15).
4.1.2. Immunohistochemical stains
Positive for endothelial markers including factor VIII–related antigen and CD31 of proliferating small blood vessels. [17-19]
Malignant neoplasm with only fibroblastic/myofibroblastic differentiation (Figure 16).
4.2.2. Immunohistochemical stains
Vimentin, and rarely, focal actin positivity. [40, 41]
Uncommon, high-grade malignant vascular neoplasm, occasionally associated with radiation.
4.3.2. Immunohistochemical stains
Positive with CD34, CD31, factor VIII–RAg, vimentin, podoplanin. ERG shows nuclear positivity in nearly 100% of angiosarcomas. FLI1 expression is found in as many as 100% of angiosarcomas, but utility is limited by poor specificity for vascular lesions. CD31 expression is found in more than 90% of angiosarcomas (Figure 17).
VEGFR3 expression is found in approximately 50% of angiosarcomas, [42-50]
4.4. Kaposis sarcoma
Kaposi sarcoma is a malignant neoplasm of endothelial cells. Oral lesions are commonly multifocal. Early lesions: are flat, red, and asymptomatic. Older lesions: larger, darker, nodular, and ulcerated. KS is common in patients with AIDS.
Malignant tumor of smooth muscle
4.5.2. Immunohistochemical stains
Currently, IHC confirmation of smooth muscle differentiation in LMS is based on the demonstration of desmin, α–SMA, muscle actin (HHF-35), and h-Caldesmon PAS with diastase will highlight intracellular glycogen. Tumor cells will be strongly and diffusely reactive with vimentin and actins (smooth muscle, muscle-specific), while variably positive for desmin [49, 50, 51, 52, 53, 54] (Figure 19) [52-57].
4.6. Synovial sarcoma
Synovial sarcoma is a malignant soft tissue tumor that shows epithelial and mesenchymal differentiation and has distinct clinical, genetic, and morphologic features.
Although it was once thought that synovial sarcoma arose in association with synovium, it is now well known that this is not the case and that these tumors may arise at any anatomic location.
4.6.2. Immunohistochemical stains
Morphologically, synovial sarcoma takes three main forms: 1) biphasic, 2) monophasic, and 3) poorly differentiated. Biphasic synovial sarcoma (BSS) consists of a fascicular spindle cell component and an epithelial component that usually shows glandular differentiation, whereas monophasic synovial sarcoma (MSS) lacks the epithelial component. The glandular component of synovial sarcoma expresses cytokeratins, including AE1/AE3. EMA expression is typically observed in both BSS and MSS. however, unlike its biphasic counterpart, MSS tends to be focally and inconsistently reactive for cytokeratins.
In particular, MSS may show reactivity for simple keratins: CK7, CK8, CK18, and CK19. S-100 protein expression is found in approximately 30% of synovial sarcomas. CD99 is commonly observed in MSS, but expression of this marker is also shared by some other spindle cell neoplasms. Strong positivity for BCL2 protein has also been noted in the spindle cell component of synovial sarcoma. [55-58]. TLE1 is positive in synovial sarcoma (Figure 20).
A malignant neoplasm with skeletal muscle phenotype: Embryonal type (80%): Alveolar type (20%)
4.8. Granular cell tumor
This is an uncommon tumor composed of poorly demarcated granular cells, thought to be Schwann-cell derived, that frequently arise below a mucosa, the latter often showing pseudoepitheliomatous hyperplasia. Granular cell tumor tends to affect the oral cavity (tongue most commonly). Tumors are usually smooth surfaced, poorly demarcated, and are often polypoid, and measure from1 to 2 cm.
5. Hematologic disorders
The common hematologic disorders that need IHC stains are;
Non – Hodgkin's lymphoma
Extranodal NK/T-Cell lymphoma, (angiocentric T-cell lymphoma) Midline lethal granuloma
5.1. Hodgkins lymphoma
This almost always begins in the lymph nodes, and any lymph node group is susceptible.
The most common sites of initial presentation are the cervical and supraclavicular nodes (70% to 75%). Hodgkin's lymphoma is currently classified in the following manner:
5.1.1. Immunohistochemical stains
The antibodies most commonly used for diagnosing HL are Ber-H2 (CD30), LeuM1 (CD15), LCA (CD45), L26 (CD20), CD75 (LN1), CD74 (LN2), PAX5, CD3, UCHL1 (CD45RO), ALK, fascin, and EBV-LMP1. EMA and CD57 can be used to recognize NLPHL.
Monoclonal antibody LN1 reacts with H/RSCs in approximately one third of HL cases, most frequently in cases of NLPHL (>75% of cases)(Figure 23). [17-19]
5.2. Non- Hodgkins lymphoma
Non-Hodgkin's lymphoma most commonly develops in the lymph nodes, In the oral cavity. Lymphoma usually appears as extranodal disease. The malignancy may develop in the oral soft tissues or centrally within the jaws; they most commonly affect the buccal vestibule, posterior hard palate, or gingiva.
5.2.2. Immunohistochemical stains
Small Cell Lymphoid Neoplasms
The lymphoma cells express pan–B-cell antigens (CD19, CD20, CD22, PAX-5). Mantle cell lymphoma (MCL) expresses pan–B-cell antigens (CD19, CD20, CD22), CD5, CD43, Bcl-2, and cyclin D1.
Nodal marginal zone lymphoma (NMZL) will typically express pan–B-cell antigens that include CD19, CD20, PAX5, and CD79a;
Co-expression with Bcl-2 and CD43 is common and occurs in 50%. The vast majority of low-grade follicular lymphoma (FL) are positive for Bcl-2 small lymphocytic lymphoma (CLL/SLL) includes expression of CD5, CD23, CD19, CD43, and Bcl-2 and has a proliferation rate of less than 10%. [17-19] (Figure 24).
Large B-Cell Lymphoid Neoplasms
CD15 expression +
CD45 expression +
PAX5 strong, uniform + CD20 strong, uniform +.
CD79a expression +.
T-Cell Lymphoid Neoplasms
Almost all peripheral T-cell lymphomas express pan–T-cell antigens CD3, CD2, and CD43. Anaplastic large-cell lymphoma (ALCL) is positive for CD30, and the expression should be strong and in at least 75% of the cells.
The neoplastic cells of angioimmunoblastic T-cell lymphoma)AITL) are positive for pan–T-cell antigens CD3, CD2, CD5, [17-19]
5.3. Extranodal NK/T-cell lymphoma, (angiocentric T-cell lymphoma) midline lethal granuloma
NK/T-cell lymphoma is the most common malignant nonepithelial neoplasm found in the upper respiratory tract and most commonly involves the nasal cavity, the maxillary sinus, nasopharynx, and salivary gland. This discussion will be limited to extranodal NK/T-cell lymphoma, nasal type (NK/T LNT), which is more common in the sinonasal region.
5.3.2. Immunohistochemical stains
NK cells express CD2, CD7, CD8, CD56, and CD57. They are positive for cytoplasmic CD3, but not surface CD3, and do not typically express CD5. The neoplastic counterpart, extranodal NK/T-cell lymphomas, express CD2, cytoplasmic CD3, CD56, and, in most cases, EBV. [17-19] (Figure 25, 26).
5.4. Burkitts lymphoma
Burkitt's lymphoma is a malignancy of B-lvmphocyte origin that represents an undifferentiated lymphoma. The tendency for jaw involvement seems to be age related: nearly 90% of 3-year-old patients have jaw lesions.
5.4.2. Immunohistochemical stains
There were statistically significant differences in the expression of CD10 (28/28 vs. 1/16), bcl-2 (3/28 vs. 11/16), MUM1 (5/28 vs. 15/16), a PI of 95. 0% or more (27/28 vs. 2/16), and combined CD10+/bcl-2-/bcl-6+ (24/28 vs. 1/16) between BLs and DLBCL-HPSSs. Of the BLs, 7 (25%) of 28 and 26 (96%) of 27 were positive for EBER and c-myc rearrangement as compared with 0 of 16 and 1 (7%) of 15 DLBCL-HPSSs, respectively as compared with 0 of 16 and 1 (7%) of 15 DLBCL-HPSSs, respectively. [17-19, 63]
6. Bone tumors
The common bone tumors needing IHC are:
Osteosarcoma is the most common nonhematopoietic primary malignant bone tumor ; it is a malignant mesenchymal tumor producing osteoid from the tumor cells (Figure 28).
6.1.2. Immunohistochemical stains
CD99 positive; rare cytokeratin and smooth muscle actin reaction. Overall, the reported specificity of immunoreactivity for osteonectin and osteocalcin is approximately 40% and 95%, respectively, for the diagnosis of a bone forming tumor. A recent promising marker for identification of osteoblastic differentiation is SATB2, a nuclear matrix protein that plays a role in osteoblast lineage commitment. α-SMA and desmin, which can lead to misdiagnosis. [63-69]
Chondrosarcoma is a malignant tumor of bone that shows pure cartilaginous differentiation. Secondary changes that include myxoid features, ossification, and calcification may be present. (Figure 29).
6.2.2. Immunohistochemical stains
Cartilage stains S100 protein positive Mesenchymal chondrosarcoma: Sox9, CD99, and Leu7 positive Although the cartilaginous component of mesenchymal chondrosarcoma is S-100 protein positive, the small-cell component expresses CD99, CD57, and NSE therefore immunohistochemically, there may also be overlap with Ewing sarcoma. However, unlike Ewing sarcoma, MCS is nonreactive for synaptophysin and also typically does not express desmin, actin, cytokeratin, or EMA. In addition, MCS lacks EWSR1 gene rearrangements. However, a recent study has identified a novel HEY1-NCOA2 fusion in MCS which appears to be a consistent finding. [70, 71]