Immunohistochemistry tumour pathology

Immunohistochemistry: tumour pathology

Immunohistochemistry has multiple applications in tumour pathology , including elucidation of site of origin and determi nation of cell type/direction of di ff erentiation. Immunohisto chemistry may also help to confirm neoplasia, determine the selection of treatment, refine prognostic predictions and screen for known underlying genetic changes. Numerous immunohistochemical stains help to deter mine cell type in tumours . Epithelial cells express cytokera tins. Therefore, cytokeratin positivity , though not diagnostic, favours carcinoma ( Figure 11.25 ) over other types of malig nancy . Lymphoid markers include the panlymphoid marker CD45, the T-lymphocyte marker CD3 and the B-lymphocyte marker CD20. Markers of melanocytic di ff erentiation include S100, MelanA and HMB45. Chromogranin, synaptophysin Summary box 11.11 Some immunohistochemical stains used for tumours /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF typically expresses CD117 ( Figure 11.26 ) and DOG-1. Endo - thelial cell markers include CD31, which may confirm a diag - nosis of vascular neoplasia or highlight vascular invasion by tumours. H&E appearances may indicate or suggest the anatomical site of origin of a metastatic tumour. For example, an adeno - carcinoma has sev eral possible sources such as gastrointestinal tract, pancr eatobiliary system, bronchus, breast and gynaeco - ) is often of logical tract. A clear cell carcinoma ( Figure 11.17 renal origin but could be from the liver, pancreas, parathyroid or endometrium, among other sites. Immunohistochemical stains often provide valuable further information about ana - tomical origin. Some are highly specific for a particular site , e.g. prostate-specific antigen (PSA) and thyroglobulin. Others are somewhat less specific, e.g. thyroid transcription factor-1 (TTF-1), a marker of bronchogenic or thyroid origin; hepato - cyte-specific antigen, suggesting hepatocellular origin; and cytokeratin 20, typically expressed by colorectal epithelium. veral types of Carcinoembryonic antigen (CEA) is present in se carcinoma ( Figure 11.22b ). In practice, pathologists encoun - - tering a neoplasm of uncertain origin or uncertain phenotype - usually request a panel of markers relevant to the clinical set - , espe - ting and to the H&E appearances. Some malignancies cially poorly di ff erentiated examples, do not conform to the - - -

Cell type/site of origin Epithelial (carcinoma): cytokeratins Lymphoid (lymphoma): CD45, CD3 (T cells), CD20 (B cells) Melanocytic (melanoma): S100, HMB45, Melan A Neuroendocrine: synaptophysin, chromogranin Vascular: CD31 Myoid: desmin, actin Site of origin/cell type Prostate: prostate-speci /f_i c antigen (PSA) Lung: thyroid transcription factor-1 (TTF-1) Thyroid: thyroglobulin Colorectum: cytokeratin 20 (CK20), CDX2 Liver: hepatocyte-speci /f_i c antigen (HSA) Gastrointestinal stromal tumour (GIST): CD117, DOG-1 Prognosis and treatment Breast carcinoma and gastric carcinoma: HER-2 Neuroendocrine tumours: Ki67 proliferation index Screening for mutations Colorectal carcinoma: mismatch repair proteins (MLH1, MSH2, MSH6, PMS2) (a) (b) Figure 11.26 (a) A metastatic tumour composed of spindle cells. The clinical team suspected a diagnosis of gastrointestinal stromal tumour (GIST). (b) Positive immunohistochemistry for CD117, supporting a diagnosis of GIST.

typical immunohistochemical profiles. In all circumstances, interpretation takes place in the light of the clinical picture and imaging findings. Less often, immunohistochemistry helps to confirm malig nancy . For example, kappa or lambda light chain restriction (expression of only one immunoglobulin light chain) in lym phoid proliferations suggests clonality and, in turn, neoplasia rather than a reactive process . In general, immunohistochem istry does not distinguish well between benign and malignant. Immunohistochemistry also plays a role in the selection of tr eatment and in predicting prognosis. For example, assessment of oestrogen receptor (ER) and human epidermal gro wth fac tor receptor-2 (HER2) status is routine for carcinomas of the breast (see Immunohistochemistry: tumour pathology while lymphomas are typically subjected to a comprehensive panel of mar kers that help determine treatment and prognosis. Ki67 proliferative index is an important prognostic factor for neuroendocrine neoplasms ( Figure 11.27 ) . Immunohistochemistry: infections and other applications There are antibodies to many infective agents, including cytomegalovirus (CMV), Epstein–Barr virus (EBV), herpes simplex virus, human herpes virus 8 (HHV8), hepatitis B virus and Helicobacter pylori. Some of these organisms, e.g. pylori and CMV , may be obvious or suspected on H&E exam ination, while others, e.g. EBV and HHV8, always require immunohistochemistry or other techniques for their detection. Immunohistochemistry can also detect immunoglobulin and complement expression (e.g. in lymphomas or renal biop sies); confirm the abnormal accumulation of various proteins such as alpha-1-antitrypsin (A1AT); and help to c haracterise amyloid. Newer immunohistochemical markers that detect specific gene mutations are appearing and may become useful in clin ical practice in the futur e. An important example is screening for MMR gene mutations in most gastrointestinal carcinomas Sir Michael Anthony Epstein , b.1921, Professor of Pathology , University of Bristol, Bristol, UK. Yvonne Barr , 1931–2016, Irish born virologist who emigrated to Australia. Epstein and Barr discovered this virus in 1964. BRAF V600E can replace mutational analysis in some settings. The major advantages of immunohistochemistry over other molecular tests for detecting genetic alterations are lower cost and faster turnaround. Summary box 11.12 Uses of immunohistochemistry /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF - /uni25CF /uni25CF - -

Figure 11.27 Immunohistochemistry for Ki67. The proliferative index is approximately 35% in this /f_i eld. Cell type Neoplasia Direction of differentiation/phenotype Determination of anatomical site of origin Con /f_i rmation of neoplasia Grading Selection of treatment Detection of/screening for mutations Prognosis Microorganisms – detection Other Amyloid Immunoglobulins Complement

Immunohistochemistry: tumour pathology

Immunohistochemistry has multiple applications in tumour pathology , including elucidation of site of origin and determi nation of cell type/direction of di ff erentiation. Immunohisto chemistry may also help to confirm neoplasia, determine the selection of treatment, refine prognostic predictions and screen for known underlying genetic changes. Numerous immunohistochemical stains help to deter mine cell type in tumours . Epithelial cells express cytokera tins. Therefore, cytokeratin positivity , though not diagnostic, favours carcinoma ( Figure 11.25 ) over other types of malig nancy . Lymphoid markers include the panlymphoid marker CD45, the T-lymphocyte marker CD3 and the B-lymphocyte marker CD20. Markers of melanocytic di ff erentiation include S100, MelanA and HMB45. Chromogranin, synaptophysin Summary box 11.11 Some immunohistochemical stains used for tumours /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF typically expresses CD117 ( Figure 11.26 ) and DOG-1. Endo - thelial cell markers include CD31, which may confirm a diag - nosis of vascular neoplasia or highlight vascular invasion by tumours. H&E appearances may indicate or suggest the anatomical site of origin of a metastatic tumour. For example, an adeno - carcinoma has sev eral possible sources such as gastrointestinal tract, pancr eatobiliary system, bronchus, breast and gynaeco - ) is often of logical tract. A clear cell carcinoma ( Figure 11.17 renal origin but could be from the liver, pancreas, parathyroid or endometrium, among other sites. Immunohistochemical stains often provide valuable further information about ana - tomical origin. Some are highly specific for a particular site , e.g. prostate-specific antigen (PSA) and thyroglobulin. Others are somewhat less specific, e.g. thyroid transcription factor-1 (TTF-1), a marker of bronchogenic or thyroid origin; hepato - cyte-specific antigen, suggesting hepatocellular origin; and cytokeratin 20, typically expressed by colorectal epithelium. veral types of Carcinoembryonic antigen (CEA) is present in se carcinoma ( Figure 11.22b ). In practice, pathologists encoun - - tering a neoplasm of uncertain origin or uncertain phenotype - usually request a panel of markers relevant to the clinical set - , espe - ting and to the H&E appearances. Some malignancies cially poorly di ff erentiated examples, do not conform to the - - -

Cell type/site of origin Epithelial (carcinoma): cytokeratins Lymphoid (lymphoma): CD45, CD3 (T cells), CD20 (B cells) Melanocytic (melanoma): S100, HMB45, Melan A Neuroendocrine: synaptophysin, chromogranin Vascular: CD31 Myoid: desmin, actin Site of origin/cell type Prostate: prostate-speci /f_i c antigen (PSA) Lung: thyroid transcription factor-1 (TTF-1) Thyroid: thyroglobulin Colorectum: cytokeratin 20 (CK20), CDX2 Liver: hepatocyte-speci /f_i c antigen (HSA) Gastrointestinal stromal tumour (GIST): CD117, DOG-1 Prognosis and treatment Breast carcinoma and gastric carcinoma: HER-2 Neuroendocrine tumours: Ki67 proliferation index Screening for mutations Colorectal carcinoma: mismatch repair proteins (MLH1, MSH2, MSH6, PMS2) (a) (b) Figure 11.26 (a) A metastatic tumour composed of spindle cells. The clinical team suspected a diagnosis of gastrointestinal stromal tumour (GIST). (b) Positive immunohistochemistry for CD117, supporting a diagnosis of GIST.

typical immunohistochemical profiles. In all circumstances, interpretation takes place in the light of the clinical picture and imaging findings. Less often, immunohistochemistry helps to confirm malig nancy . For example, kappa or lambda light chain restriction (expression of only one immunoglobulin light chain) in lym phoid proliferations suggests clonality and, in turn, neoplasia rather than a reactive process . In general, immunohistochem istry does not distinguish well between benign and malignant. Immunohistochemistry also plays a role in the selection of tr eatment and in predicting prognosis. For example, assessment of oestrogen receptor (ER) and human epidermal gro wth fac tor receptor-2 (HER2) status is routine for carcinomas of the breast (see Immunohistochemistry: tumour pathology while lymphomas are typically subjected to a comprehensive panel of mar kers that help determine treatment and prognosis. Ki67 proliferative index is an important prognostic factor for neuroendocrine neoplasms ( Figure 11.27 ) . Immunohistochemistry: infections and other applications There are antibodies to many infective agents, including cytomegalovirus (CMV), Epstein–Barr virus (EBV), herpes simplex virus, human herpes virus 8 (HHV8), hepatitis B virus and Helicobacter pylori. Some of these organisms, e.g. pylori and CMV , may be obvious or suspected on H&E exam ination, while others, e.g. EBV and HHV8, always require immunohistochemistry or other techniques for their detection. Immunohistochemistry can also detect immunoglobulin and complement expression (e.g. in lymphomas or renal biop sies); confirm the abnormal accumulation of various proteins such as alpha-1-antitrypsin (A1AT); and help to c haracterise amyloid. Newer immunohistochemical markers that detect specific gene mutations are appearing and may become useful in clin ical practice in the futur e. An important example is screening for MMR gene mutations in most gastrointestinal carcinomas Sir Michael Anthony Epstein , b.1921, Professor of Pathology , University of Bristol, Bristol, UK. Yvonne Barr , 1931–2016, Irish born virologist who emigrated to Australia. Epstein and Barr discovered this virus in 1964. BRAF V600E can replace mutational analysis in some settings. The major advantages of immunohistochemistry over other molecular tests for detecting genetic alterations are lower cost and faster turnaround. Summary box 11.12 Uses of immunohistochemistry /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF - /uni25CF /uni25CF - -

Figure 11.27 Immunohistochemistry for Ki67. The proliferative index is approximately 35% in this /f_i eld. Cell type Neoplasia Direction of differentiation/phenotype Determination of anatomical site of origin Con /f_i rmation of neoplasia Grading Selection of treatment Detection of/screening for mutations Prognosis Microorganisms – detection Other Amyloid Immunoglobulins Complement

Immunohistochemistry: tumour pathology

Immunohistochemistry has multiple applications in tumour pathology , including elucidation of site of origin and determi nation of cell type/direction of di ff erentiation. Immunohisto chemistry may also help to confirm neoplasia, determine the selection of treatment, refine prognostic predictions and screen for known underlying genetic changes. Numerous immunohistochemical stains help to deter mine cell type in tumours . Epithelial cells express cytokera tins. Therefore, cytokeratin positivity , though not diagnostic, favours carcinoma ( Figure 11.25 ) over other types of malig nancy . Lymphoid markers include the panlymphoid marker CD45, the T-lymphocyte marker CD3 and the B-lymphocyte marker CD20. Markers of melanocytic di ff erentiation include S100, MelanA and HMB45. Chromogranin, synaptophysin Summary box 11.11 Some immunohistochemical stains used for tumours /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF typically expresses CD117 ( Figure 11.26 ) and DOG-1. Endo - thelial cell markers include CD31, which may confirm a diag - nosis of vascular neoplasia or highlight vascular invasion by tumours. H&E appearances may indicate or suggest the anatomical site of origin of a metastatic tumour. For example, an adeno - carcinoma has sev eral possible sources such as gastrointestinal tract, pancr eatobiliary system, bronchus, breast and gynaeco - ) is often of logical tract. A clear cell carcinoma ( Figure 11.17 renal origin but could be from the liver, pancreas, parathyroid or endometrium, among other sites. Immunohistochemical stains often provide valuable further information about ana - tomical origin. Some are highly specific for a particular site , e.g. prostate-specific antigen (PSA) and thyroglobulin. Others are somewhat less specific, e.g. thyroid transcription factor-1 (TTF-1), a marker of bronchogenic or thyroid origin; hepato - cyte-specific antigen, suggesting hepatocellular origin; and cytokeratin 20, typically expressed by colorectal epithelium. veral types of Carcinoembryonic antigen (CEA) is present in se carcinoma ( Figure 11.22b ). In practice, pathologists encoun - - tering a neoplasm of uncertain origin or uncertain phenotype - usually request a panel of markers relevant to the clinical set - , espe - ting and to the H&E appearances. Some malignancies cially poorly di ff erentiated examples, do not conform to the - - -

Cell type/site of origin Epithelial (carcinoma): cytokeratins Lymphoid (lymphoma): CD45, CD3 (T cells), CD20 (B cells) Melanocytic (melanoma): S100, HMB45, Melan A Neuroendocrine: synaptophysin, chromogranin Vascular: CD31 Myoid: desmin, actin Site of origin/cell type Prostate: prostate-speci /f_i c antigen (PSA) Lung: thyroid transcription factor-1 (TTF-1) Thyroid: thyroglobulin Colorectum: cytokeratin 20 (CK20), CDX2 Liver: hepatocyte-speci /f_i c antigen (HSA) Gastrointestinal stromal tumour (GIST): CD117, DOG-1 Prognosis and treatment Breast carcinoma and gastric carcinoma: HER-2 Neuroendocrine tumours: Ki67 proliferation index Screening for mutations Colorectal carcinoma: mismatch repair proteins (MLH1, MSH2, MSH6, PMS2) (a) (b) Figure 11.26 (a) A metastatic tumour composed of spindle cells. The clinical team suspected a diagnosis of gastrointestinal stromal tumour (GIST). (b) Positive immunohistochemistry for CD117, supporting a diagnosis of GIST.

typical immunohistochemical profiles. In all circumstances, interpretation takes place in the light of the clinical picture and imaging findings. Less often, immunohistochemistry helps to confirm malig nancy . For example, kappa or lambda light chain restriction (expression of only one immunoglobulin light chain) in lym phoid proliferations suggests clonality and, in turn, neoplasia rather than a reactive process . In general, immunohistochem istry does not distinguish well between benign and malignant. Immunohistochemistry also plays a role in the selection of tr eatment and in predicting prognosis. For example, assessment of oestrogen receptor (ER) and human epidermal gro wth fac tor receptor-2 (HER2) status is routine for carcinomas of the breast (see Immunohistochemistry: tumour pathology while lymphomas are typically subjected to a comprehensive panel of mar kers that help determine treatment and prognosis. Ki67 proliferative index is an important prognostic factor for neuroendocrine neoplasms ( Figure 11.27 ) . Immunohistochemistry: infections and other applications There are antibodies to many infective agents, including cytomegalovirus (CMV), Epstein–Barr virus (EBV), herpes simplex virus, human herpes virus 8 (HHV8), hepatitis B virus and Helicobacter pylori. Some of these organisms, e.g. pylori and CMV , may be obvious or suspected on H&E exam ination, while others, e.g. EBV and HHV8, always require immunohistochemistry or other techniques for their detection. Immunohistochemistry can also detect immunoglobulin and complement expression (e.g. in lymphomas or renal biop sies); confirm the abnormal accumulation of various proteins such as alpha-1-antitrypsin (A1AT); and help to c haracterise amyloid. Newer immunohistochemical markers that detect specific gene mutations are appearing and may become useful in clin ical practice in the futur e. An important example is screening for MMR gene mutations in most gastrointestinal carcinomas Sir Michael Anthony Epstein , b.1921, Professor of Pathology , University of Bristol, Bristol, UK. Yvonne Barr , 1931–2016, Irish born virologist who emigrated to Australia. Epstein and Barr discovered this virus in 1964. BRAF V600E can replace mutational analysis in some settings. The major advantages of immunohistochemistry over other molecular tests for detecting genetic alterations are lower cost and faster turnaround. Summary box 11.12 Uses of immunohistochemistry /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF /uni25CF - /uni25CF /uni25CF - -

Figure 11.27 Immunohistochemistry for Ki67. The proliferative index is approximately 35% in this /f_i eld. Cell type Neoplasia Direction of differentiation/phenotype Determination of anatomical site of origin Con /f_i rmation of neoplasia Grading Selection of treatment Detection of/screening for mutations Prognosis Microorganisms – detection Other Amyloid Immunoglobulins Complement