Immunohistochemistry (IHC) and Lung Cancer: An introduction with Moose and Doc

CONTENT:

6.5 Histochemistry (‘Special Stains’)
6.6 Immunohistochemistry (IHC)
6.6.1 Diagnostic Lung Immunohistochemistry (IHC)

Forward to 6F Use of IHC in Pathology Problems . Back to 6D Diagnosis and Diagnostic Guidelines .

All about ‘Special Stains.’ Hmmm, sounds interesting and could be fun!

6.5 Histochemistry (‘Special Stains’)

immunohistochemistry Tissue sections of lung are fixed, processed and sectioned onto glass slides. In addition, the lung sections are stained with colored (histochemical) dyes before they can be analyzed microscopically.

Histochemical stains identify the cells and their structures and identify the non-cellular tissue components under microscopic magnification.

The most common histochemical stains used in lung cancer diagnosis are:

Hematoxylin: stains cell nuclei blue/black.
Eosin: stains protein and cell cytoplasm deep pink.
When used together, hematoxylin and eosin is termed ‘H&E.’
Periodic acid Schiff (PAS): for mucin and glycogen (purple).
PAS with diastase (PASD): digests glycogen and also detects mucin (pink/purple).
Alcian Blue (AB): stains mucin (blue)

Figure 6.6 The Appearance of Mucin in Histology.

A. Photomicrograph. Normal bronchial epithelium with mucin-containing
goblet cells, stained blue with Alcian Blue. (x 100) B. Photomicrograph.
NSCLC shows focal intracytoplasmic, Alcian Blue-positive mucin, supporting
a diagnosis of adenocarcinoma. (x 60)

I love the pink and blue colours together up there.

What’s pink and fluffy? Pink fluff. What’s blue and fluffy? Pink fluff holding it’s breath.

6.6 Immunohistochemistry (IHC)

immunohistochemistry The diagnosis of benign and malignant conditions in lung pathology can be made using the H&E (hematoxylin & eosin)-stained tissue section. The type and sub-type of lung cancer may require the detection of cell markers on the tumor that are distinctive to the specific cell of origin or the malignant version of the cell type.

Immunohistochemistry (IHC) relies upon the visual detection of a specific antibody that can ‘stick’ to a cell protein that is specific to a cell type or its cancerous counterpart. Furthermore, a light microscope locates the antibodies because of the visual tags (usually a brown or red label).

Immunohistochemistry techniques have improved and developed over the past 30 years or so. The reason for this is that more specific and reliable antibodies (monoclonal antibodies) and enzymatic labels are available.

There may be limitations in the use of some antibodies used in IHC, so ‘panels’ of antibodies are often used.

Quality control guidelines for Immunohistochemistry (IHC) staining methods and their interpretation are required to be implemented by diagnostic Pathology laboratories.

IHC is used in combination with an analysis of lung tissue morphology on the H&E-stained tissue section.

Immunohistochemistry in lung histopathology has three roles: in diagnosis, in prognosis and identifying ‘predictive’ markers for lung cancer therapy.

Figure 6.7 Immunohistochemistry (IHC)

immunohistochemistry

6.6.1 Diagnostic Lung Immunohistochemistry (IHC)

accord-1 When the Pathologist examines a lung biopsy using microscopy, there are two main diagnostic challenges: the identification of tumor cells (adenocarcinoma, squamous carcinoma, small cell carcinoma) and the confirmation or exclusion of tumor cell invasion.

The most important contribution that IHC can make diagnostically is in distinguishing between adenocarcinoma and squamous cell carcinoma in a small biopsy.

Most adenocarcinomas of the lung express the following cell markers:

Cytokeratin 7 (CK7)
Thyroid transcription factor-1 (TTF-1) (nuclear staining) (70 % to 85 %). TTF-1 also stains 20 % to 30% of resected undifferentiated large cell carcinomas and 50% of large cell neuroendocrine carcinomas, as well as some metastatic adenocarcinomas.
p63 (30 %)
Some express cytokeratin 20 (CK20) (20 %)
p63
E-cadherin (100% of adenocarcinomas) and most epithelial tumors

Squamous cell carcinomas express the following cell markers:

CK5/6
p63
34bE12
and are usually negative for TTF-1 and CK7.

Morphological criteria are the most important features that may distinguish Non-Small Cell Carcinomas (NSCLC) subtypes. The use of mucin stains and an IHC ‘panel‘ that includes TTF-1, CK5/6 and p63 may be helpful.

Pancytokeratin IHC staining for AE1/AE3 would support a diagnosis of a carcinoma rather than a lymphoid lesion.

Neuroendocrine markers include CD56, chromogranin, and synaptophysin, which are best used as a panel with CD56, being positive in up to 90% of cases.

Classification of Lung Cancer and Immunohistology

immunohistochemistry The 2011 International Multidisciplinary Lung Adenocarcinoma Classification from IASLC/ATS/ERS in its guidelines for diagnosis of histological NSCLC subtypes in small biopsies and cytology samples has included an algorithm for appropriate use of mucin and immunohistochemical stains.

The logic of such approaches means that there is maximum preservation of small tissue samples so that future molecular analysis may still be possible.

Wow! That’s all quite heavy stuff.

Let’s have a cup of coffee and a donut before the complicated picture comes.

On the one hand I need to lose weight, but on the other hand… donut? Did somebody say donut?

Figure 6.8 Algorithm for the Histopathological
Subtyping of NSCLC in Small Biopsy Samples

For other situations in which a metastatic, mesenchymal or lymphoid tumor is suspected on morphology of a lung tumor biopsy, the following markers may be useful:

Melanoma markers: S100, melan-A, HMB45
Lymphoid markers: CD20, LCA, CD15, CD30
Vascular endothelial markers: CD31, CD34, Factor VIII, d2-40 (podoplanin)

Oh No! I just let my mind wander and it didn’t come back.

For tumors in the pleural and where a mesothelioma may be a possible diagnosis, there is the following diagnostic panel:-

Cytokeratin 5/6 expression is detected in 6% of the adenocarcinomas and 63% of mesotheliomas.
E-cadherin is almost 100% sensitive for pulmonary adenocarcinoma. TTF-1 is almost 100% specific for pulmonary adenocarcinoma.
Where TTF-1 is negative and E-cadherin is positive, a secondary panel of antibodies, including BerEP4 and LeuM1 (CD15) and antibodies directed against calretinin, cytokeratin 5/6 and thrombomodulin may be required for differentiation between malignant mesothelioma and pulmonary adenocarcinoma.

You just have to accept that some days you are the pigeon and some days you are the statue.

References:

Goldstein, N.S., Hewitt, S.M., Taylor, C.R., et al. (2007). Recommendations for improved standardization of immunohistochemistry. Appl Immunohistochem Mol Morphol 15, 124–33. (Retrieved 19^th Feb 2015): https://www.ncbi.nlm.nih.gov/pubmed/17525622

Bishop JA, Teruya-Feldstein J, Westra WH et al. p40 (ΔNp63) is superior to p63 for the diagnosis of pulmonary squamous cell carcinoma. Mod. Pathol.25,405–415 (2012). (Retrieved 19^th Feb 2015): https://www.ncbi.nlm.nih.gov/pubmed/22056955

More references for this section are on this page .

Patient Information:

Information on Immunohistochemistry: (Retrieved 19^th Feb 2015):

National Cancer Institute Tumor Markers (Retrieved 28^th April 2015): http://www.cancer.gov/cancertopics/diagnosis-staging/diagnosis/tumor-markers-fact-sheet

More patient information for this section is on this page .