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Home Topics A–Z Immunohistochemistry stains
Author: Brian Wu PhD. MD Candidate, Keck School of Medicine; Chief Editor: Dr Amanda Oakley, Dermatologist, Hamilton, New Zealand, July 2015.
Immunohistochemistry (IHC) is considered to be an advanced form of histopathology. Immunohistochemistry is not usually used initially but is added when routine/regular histological testing is insufficient to form a diagnosis.
IHC uses primary antibodies to label a protein, then uses a secondary antibody which is bound to the primary one. In immunoperoxidase staining, an antibody is joined to an enzyme, peroxidase, that catalyses a reaction in which the protein is specifically stained brown. IHC can also involve fluorescently labelled antibody so that when viewed under a light microscope a certain pattern will be observed from the emitted fluorescence.
The IHC pattern is considered diagnostic, demonstrating nuclear, membranous or cytoplasmic patterns. IHC is often used in situations where a presence or absence of certain proteins can form a basis for a diagnosis. It can also be used to distinguish between two different disease processes that may otherwise appear similar to the pathologist.
The most common process of preparing immunohistochemical slides is as follows:
The advantages of IHC include:
The disadvantages of IHC are as follows:
Hundreds of immunohistochemical stains are used to identify different tumours and other neoplasms. Just a few of the IHC stains used in dermatology are listed below.
IHC Stain | Uses/Image caption |
---|---|
BCL2 | Used to distinguish between basal cell carcinomas and trichoepitheliomas |
CD3 | T-cell marker; strongly positive in mycosis fungoides |
CD4 | Helper T-cell marker |
CD8 | Suppressor T-cell marker |
CD20 | B-cell marker |
CD30 | Can be used in the diagnosis of Hodgkin lymphoma and anaplastic lymphomas. Large cells: Golgi apparatus and membranous staining |
CD31 | Helps to identify endothelial tumour |
CD34 | Distinguishes different endothelial tumours and is positive in dermatofibrosarcoma |
CD56 | Used in the diagnosis of non-Hodgkin lymphomas, leukaemias and small cell carcinomas |
CD117 | Marker for KIT receptor and positive in various tumours including mastocytosis |
CDKN2A (p16) | Tumour suppressor marker positive in HPV-associated tumours, actinic keratoses and squamous cell carcinoma |
CK (various) | Cytokeratins can be used to help distinguish benign from malignant adnexal tumours |
CK 20 | Specific for Merkel cell carcinoma. Can help identify adenocarcinomas of the gastrointestinal and reproductive system as well as gastrointestinal epithelial tumours |
Cytokeratin High Molecular Weight | Used to detect ductal carcinomas, squamous cell carcinomas and other epithelial neoplasms |
Desmin | Muscle marker |
EMA | Used to identify eccrine neoplasms, Paget disease and sebaceous carcinomas |
Factor 13 | Can help clinicians distinguish between dermatofibrosarcoma and dermatofibroma |
HHV8 | Human herpesvirus 8 |
HMB 45 | Used to detect melanocytes, especially in melanoma but negative in desmoplastic melanoma |
Melan-a | Can help identify melanocytic naevus cells and melanomas |
PDL1 | Programmed death-ligand 1 |
S-100 | Used to mark tumours of the melanocytes, both naevi and melanoma |
SMA | Smooth muscle antigen |
SOX-10 | Nuclear marker for melanocytic tumours |
Treponema pallidum | Demonstrates organisms in secondary syphilis |
Immunohistochemistry stains
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