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  • Introduction
  • Ck 1
  • Ck 5
  • Ck 10
  • Ck 14
  • Ck HMW

 Cytokeratins are intermediate filaments present in all epithelial cells, and also in a number of non-epithelial cells. In fact, cytokeratin positively has been reported in almost every tumour type, including uterine smooth muscle tumours, most soft tissue sarcomas, melanomas, gliomas, plasmacytomas and occasionally lymphomas.

Cytokeratins can be differentiated into light and heavy chain based on their molecular weight as well as acidic which are cytokeratins 9-20 or basic which are cytokeratins 1-8.

Diagnostic utility

  • Identification of carcinomas
  • Identification of sarcomas showing true epithelial differentiation like synovial sarcoma or epithelioid sarcoma
  • CK 1 is a keratin protein found in humans. This has several uses but as can be seen in Ck5.2, it is most useful when combined with Ck 18.

    Picture 1 – CK 1 positivity in Cervix

     

    Ck 1 has several different applications. Below are a few examples.

    Tumour

    CK 8 + or -

    Epitheliod sarcoma

    Positive

    GIST or Gastrointestinal Tumour

    Positive

    Angiosarcoma

    Positive in 85% of cases, but has specificity issues

    Karposi Sarcoma

    Variable positive in about 85% of cases, but has specificity issues

    Synovial Sarcoma

    Negative

    CK 5 is found in most simple ductal and gladular epithelia. A cytoplasmic staining is produced as shown below in the colon but also skin can be used as a control in diagnostic settings. Again this is most useful when combined with CK8.

    Picture 2 – CK 5 positivity in bronchial biopsy

     

    CK 5/6 has several different applications. Below are a few examples.

    Tumour

    CK 5/6 + or -

    Epitheliod sarcoma

    Positive

    GIST or Gastrointestinal Tumour

    Positive

    Angiosarcoma

    Positive in 85% of cases, but has specificity issues

    Karposi Sarcoma

    Variable positive in about 85% of cases, but has specificity issues

    Synovial Sarcoma

    Negative

    CK 10 reacts with a range of epithelial malignancies. These inclue as shown below adenocarcinomas of colon, stomach, pancreas, liver and breast. A cytoplasmic staining is produced as shown below in the colon but also skin can be used as a control in diagnostic settings.

    Picture 3 – CK 10 positivity in breast cancer

     

    CK 10 has several different applications. Below are a few of the most common examples.

    Tumour

    CK 19 + or -

    Papillary Thyroid Carcinoma

    Positive

    Thyroid Follicular Carcinoma

    Positive - around 50/60% of the time

    Pancreas Ductal Carcinoma

    Positive

    Neuroendocrine Tumour

    Variable positive in about 50% of cases

    Pancreatoblastoma

    Negative

    CK 14 has several different applications. It produces a cytoplasmic staining which is very useful in distinguishing adnemocarcinoma and non-keratinizng squamous cell carcinoma from kertainizing squamous cell carcinoma.

    Picture 4 – CK 14 positivity in Tonsil

     

    As can be seen below CK 14 has several different applications. Below are a few examples.

    Tumour

    CK 14 + or -

    Peripheral nerve sheath

    Positive

    Spindle squamous cell carinoma

    Positive

    Kaposiform Hemangioendothelioma

    Positive

    Keratinizing squamous cell carcinoma

    Negative

    Karposi Sarcoma

    Negative

    CK HMW or AE3 (Also known as 34BE12) recognises all basic cytokeratins and it is a broadly reactive antibody staining most epithelia and neoplasms. It produces a cytoplasmic staining and is useful in distinguishing Prostatic Adenocarcinoma from Hyperplasia of the Prostate.

    Picture 5 – CK HMW positivity in Prostate

     

    As can be seen below CK HMW has several different applications. Below are a few examples.

    Tumour

    CK HMW + or -

    Prostatic Hyperplasia

    Positive

    Squamous cell carinoma

    Positive

    Hepatoma

    Positive

    Prostatic adenocarcinoma

    Negative

    Renal Cell carcinoma

    Negative