CK5 is a high molecular weight cytokeratin that stains stratified squamous epithelium (e.g. skin, tongue mucosa, etc.), basal cells of the prostate gland, myoepithelial cells in breast tissue, and mesothelial cells/mesothelioma.  Therefore CK5 is an excellent marker, which can be used in a variety of diagnostic applications.

 

CK5 is useful in the diagnosis of squamous cell carcinoma, urothelial carcinoma, mesothelioma, thymic tumors, and skin appendage tumors.  It is also helpful in identifying the myoepithelial layer in breast tissue, and the basal layer in prostate tissue.

 

The combined expression of p63 and CK5 in poorly differentiated tumors is highly suggestive of squamous origin (Kaufmann, O., et al)

CK5 will stain approximately 70-80% of squamous cell carcinomas with a cytoplasmic staining pattern.  p63 is considered slightly more sensitive, but may give varying positivity in cases of lung adenocarcinoma that can be confusing.  Therefore, CK5 and p63 are often used as part of a panel to diagnose squamous cell carcinoma.  Since p63 is a nuclear marker, these two stains can be performed as a double stain on a single slide with one or two different chromogens.

CK5 is an excellent marker for the basal layer, and stains in a similar pattern to 34βE12.  Again, CK5 can be combined with p63, which also stains the basal layer of prostate glands.

 

Bladder

CK5 will stain the myoepithelial layer of breast tissue, but other markers such as smooth muscle myosin and calponin are typically used more commonly.  Basal-like breast carcinomas usually express CK5, especially with the monoclonal CK5 antibody compared to CK5/6 (Bhargava, R, et al).  Metaplastic/sarcomatoid breast carcinomas have also been reported to express CK5.

CK5 will stain the stratified squamous epithelium.  If there are cells in the squamous epithelium, which may be Paget cells or melanocytes, CK5 can be used along with CK7 or Melan A/HMB-45 to differentiate between odd appearing keratinocytes, Paget’s disease, or melanocytes.

There is occasionally discussion as to which is a better marker.  Some feel CK5/6 is a better marker since it has more than one cytokeratin in it’s cocktail.  However, there is a very strong consensus among pathologists who have used both that CK5 performs significantly better than CK5/6, and is therefore, the preferred antibody.  

 

Common expression patterns in carcinoma (Chu, PG, et al).

 

Note:  other references note a much higher + expression pattern in meotheliomas.  This may be dependent upon the mix of epithelial and sarcomatous variants.

Cyclin D1 (bcd-1) is most commonly used diagnostically for confirming the diagnosis of mantle cell lymphoma (positivity should be diffuse, but intensity may be variable).   It has also been described to be expressed in invasive breast carcinoma.  While it is generally considered a specific marker (given the differential diagnosis usually with CLL/SLL), and can also be expressed in plasma cell neoplasms (40%) and hairy cell leukemia (25%).  One can also often see focal nuclear expression in vascular endothelial cells and other stromal cells, which should not be interpreted as focal positivity.

 

Given the small but variable expression of CD23 between CLL/SLL and Mantle cell lymphoma, including CyclinD1 in the standard IHC panel for this differential is recommended.

Recently cyclin D1 expression in proliferation centers of cases of CLL/SLL have been described, which should not be confused with diffuse expression encountered in cases of mantle cell lymphoma. 

There are several clones available, but the most sensitive marker is the rabbit monoclonal antibody from Biocare Medical.  Other clones are not recommended.

Gradowski, J. F., Sargent, R. L., Craig, F. E., Cieply, K., Fuhrer, K., Sherer, C., & Swerdlow, S. H. (2012). Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma With Cyclin D1 Positive Proliferation Centers Do Not Have CCND1 Translocations or Gains and Lack SOX11 Expression. American Journal of Clinical Pathology, 138(1), 132–139. doi:10.1309/AJCPIVKZRMPF93ET

 

Bone Marrow IHC.  Torlakovic, EE, et. al. American Society for Clinical Pathology Pathology Press © 2009.  pp. 221.

Chromogranin A is a very specific marker for neuroendocrine cell differentiation (reacts with cytoplasmic neurosecretory granules).  Unfortunately, it is not highly sensitive.  It is often used as part of a panel to identify neuroendocrine neoplasms (e.g. synaptophysin, CD56).  It is more often positive in well-differentiated lesions, and stains the neurosecretory granules in the cell cytoplasm.

 

Chromogranin A is expressed in approximately 30% of small cell carcinomas and neuroblastomas.

Wick, MR. “Immunohistochemical approaches to the diagnosis of undifferentiated malignant tumor.”Annals of Diagnostic Pathology12(2008):72-84.

CEA (carcinoembryonic antigen), CD66e, comes as either a polyclonal (pCEA) or monoclonal (mCEA) stain.  CEA is generally used as an epithelial marker with strong expression in adencarcinomas.  CEA is strongly expressed in colorectal adenocarcinomas, but it is not a specific marker as many other epithelial tumors may show expression.  CEA is most commonly used as part of a panel to discriminate between metastatic carcinoma (positive) and mesothelioma (negative).

Wick, MR. “Immunohistochemical approaches to the diagnosis of undifferentiated malignant tumor.”Annals of Diagnostic Pathology12(2008):72-84.

CDX-2 is a nuclear transcription marker that regulates differentiation and proliferation of intestinal epithelial cells, and also serves as tumor suppressor gene.  CDX-2 is normally expressed in small and large intestine epithelium.  It is a sensitive marker for colorectal adenocarcinomas (especially with strong diffuse expression).  It can also mark non-colorectal GI adenocarcinomas, columnar cell variant of papillary thyroid carcinoma (and other variants of papillary thyroid carcinoma, classic and modular variant),  ovarian mutinous carcinomas, bladder adenocarcinomas, goblet cells in Barrett’s esophagus, along with other tumors (data in tables below). Practically speaking, if a particular tumor can have any type of intestinal differentiation, then it most likely can have CDX-2 expression.

It is important to note that antibody sensitivity can have significant inter laboratory variation due to both clone selection and antibody optimization (Borrisholt, et. al.).  Each laboratory should have a good understanding of the performance characteristics of their CDX-2 clone and optimization.

 

IHC Survey of Primary and Metastatic Caricnomas (Werling, R. W., et. al.)

 

Common expression patterns in carcinoma (Dennis, J. L, et. al.)

 

(Enriquez, M.L., et. al.)

 

CDX-2 and Villin expression in human tumors (2-3+ expression) (Werling, R.W., et. al.)

Werling, R. W., Yaziji, H., Bacchi, C. E., & Gown, A. M. (2003). CDX2, a highly sensitive and specific marker of adenocarcinomas of intestinal origin: an immunohistochemical survey of 476 primary and metastatic carcinomas. The American Journal of Surgical Pathology, 27(3), 303–310.  Link: http://www.ncbi.nlm.nih.gov/pubmed/?term=American+Journal+of+Surgical+Pathology%2C+27(3)%2C+303%E2%80%93310. 

 

Dennis, J. L., Hvidsten, T. R., Wit, E. C., Komorowski, J., Bell, A. K., Downie, I., et al. (2005). Markers of adenocarcinoma characteristic of the site of origin: development of a diagnostic algorithm. Clinical Cancer Research : an Official Journal of the American Association for Cancer Research, 11(10), 3766–3772. doi:10.1158/1078-0432.CCR-04-2236  Link:  http://www.ncbi.nlm.nih.gov/pubmed/?term=Markers+of+adenocarcinoma+characteristic+of+the+site+of+origin%3A+development+of+a+diagnostic+algorithm 

 

Enriquez, M. L., Baloch, Z. W., Montone, K. T., Zhang, P. J., & LiVolsi, V. A. (2012). CDX2 expression in columnar cell variant of papillary thyroid carcinoma. American Journal of Clinical Pathology, 137(5), 722–726. doi:10.1309/AJCPXE3PUBWVZCGZ Link:  http://www.ncbi.nlm.nih.gov/pubmed/22523209

 

Cameselle-Teijeiro, J., Alberte-Lista, L., Peteiro-Gonzalez, D., Abdulkader-Nallib, I., Reyes-Santias, R., Soares, P., et al. (2012). CDX2 Expression in Some Variants of Papillary Thyroid Carcinoma. American Journal of Clinical Pathology, 138(6), 907–910. doi:10.1309/AJCP1BGCA6MFCNKH  Link:  http://www.ncbi.nlm.nih.gov/pubmed/23161723 

 

Borrisholt, M., Nielsen, S., & Vyberg, M. (2013). Demonstration of CDX2 is highly antibody dependant. Applied Immunohistochemistry & Molecular Morphology : AIMM / Official Publication of the Society for Applied Immunohistochemistry, 21(1), 64–72. doi:10.1097/PAI.0b013e318257f8aa Link: http://www.ncbi.nlm.nih.gov/pubmed/?term=Demonstration+of+CDX2+is+highly+antibody+dependant 

 

Werling, R. W., Yaziji, H., Bacchi, C. E., & Gown, A. M. (2003). CDX2, a highly sensitive and specific marker of adenocarcinomas of intestinal origin: an immunohistochemical survey of 476 primary and metastatic carcinomas. The American Journal of Surgical Pathology, 27(3), 303–310. Link: http://www.ncbi.nlm.nih.gov/pubmed/?term=CDX2%2C+a+highly+sensitive+and+specific+marker+of+adenocarcinomas+of+intestinal+origin%3A+an+immunohistochemical+survey+of+476+primary+and+metastatic+carcinomas 

Common expression patterns in carcinoma [Clin Cancer Res 2005;11(10) May 15, 2005]

Dennis, J. L., Hvidsten, T. R., Wit, E. C., Komorowski, J., Bell, A. K., Downie, I., et al. (2005). Markers of adenocarcinoma characteristic of the site of origin: development of a diagnostic algorithm. Clinical Cancer Research : an Official Journal of the American Association for Cancer Research, 11(10), 3766–3772. doi:10.1158/1078-0432.CCR-04-2236 

CAM5.2 is an antibody clone manufactured by Becton Dickinson (BD), which shows reactivity to CK8 primarily and CK7 to a less extent.  It does not demonstrate reactivity to CK18 or CK19.  Sometimes CAM5.2 has been used interchangeably with CK8/18 in the medical literature, which is not correct (Hsu, JD, et al).  It is an excellent screening marker for poorly differentiated carcinomas, micro-metastasis of carcinoma in lymph nodes, and for characteristic peri-nuclear dot-like reactivity in Merkel cell carcinoma.

 

AE1/AE3 is generally the most common screening cytokeratin marker used, which has both high and low molecular weight cytokeratins.  Rarely AE1/AE3 may not stain a poorly differentiated carcinoma, which will mark with CAM5.2.

 

CAM5.2 may occasionally stain myofibroblasts and smooth muscle cells, which may express cytokeratins in certain situations (Moll, RT, et al).

 

Moll, RT, et al.  Cytokeratin expression in various tumors.

Key:  “+/-“, focal staining in some cases. “=“, negative, “+”, positive.

---

Tamas, EF, Epstein, JI. (2007).  Detection of residual tumor cells in bladder biopsy specimens:  pitfalls in the interpretation of cytokeratin stains.  American Journal of Surgical Pathology, Mar;31(3):390-7.

 

Moll, R., Divo, M., & Langbein, L. (2008). The human keratins: biology and pathology. Histochemistry and Cell Biology, 129(6), 705–733. doi:10.1007/s00418-008-0435-6 

 

Hsu, J.-D., Yao, C.-C., Han, L.-W., & Han, C.-P. (2010). CAM5.2 is not identical to cytokeratins 8 and 18. American Journal of Clinical Pathology, 133(3), 514. doi:10.1309/AJCPAKB6JEBVMX5U  

Calretinin is a very sensitive marker used most commonly as a positive marker for mesothelioma.  It is expressed in >80% of epithelial and up to 70% of sarcomatous subtypes, staining in a cytoplasmic and nuclear pattern.  It is recommended to be used as part of a panel (2 mesothelial markers and 2 adenocarcinoma markers) since there are no sensitive and specific markers to differentiate mesothelioma from adenocarcinoma.

Arch Pathol Lab Med- Vol. 134, February 2010 p. 208.

Wick, MR. “Immunohistochemical approaches to the diagnosis of undifferentiated malignant tumor.”Annals of Diagnostic Pathology12(2008):72-84.