Cytokeratin 19

Cytokeratin 19 is the lowest molecular weight cytokeratin.

Immunohistochemical expression

• all fetal epithelium from 12 to 16 weeks gestation⁴

• fetal myocardium

• pancreatic ducts but not islet cells⁴

• carcinomas:

  • consistently positive in papillary carcinoma of thyroid but less so in other types of thyroid carcinoma and usually negative in follicular adenomas².

  • colon: 16/16³

  • breast: 5/5³

• variably in pancreatic endocrine tumours⁴

• some myeloid neoplasms

• CD30-positive lymphomas

• some leiomyosarcomas

• rare PNET/Ewing's sarcoma

• bile ducts and cholangiocarcinoma but usually not hepatocellular carcinoma¹.

Diagnostic utility

• In thyroid lesions, positivity for cytokeratin 19 favours a papillary carcinoma and may be useful in the identification of the follicular variant of papillary carcinoma. Conversely, the absence of immunoreactivity for CK19 in areas of papillary hyperplasia in any lesion may help to avoid the misdiagnosis of papillary carcinoma².

• Differentiation of hepatocellular carcinoma from cholangiocarcinoma and metastatic carcinoma

• The strong staining of bile duct epithelium in cirrhotic liver may help to distinguish cirrhosis from neoplastic liver¹.

• Prediction of malignant behaviour in pancreatic endocrine tumours⁴.

References

Diagnostic Immunohistochemistry edited by Professor D. J. Dabbs, page 61.

¹Leong, A. S., Sormunen, R. T., Tsui, W. M., Liew, C. T. Hep Par 1 and selected antibodies in the immunohistological distinction of hepatocellular carcinoma from cholangiocarcinoma, combined tumours and metastatic carcinoma. Histopathology 1998;33:318-324.

²Beesley, M.F. and McLaren, K.M. Cytokeratin 19 and galectin-3 immunohistochemistry in the differential diagnosis of solitary thyroid nodules. Histopathology 2002;41:236-43.

³Jerome Marson, V., J. Mazieres, et al. (2004). "Expression of TTF-1 and cytokeratins in primary and secondary epithelial lung tumours: correlation with histological type and grade." Histopathology 45(2): 125-34.

⁴Deshpande, V., C. Fernandez-del Castillo, et al. (2004). "Cytokeratin 19 is a powerful predictor of survival in pancreatic endocrine tumors." Am J Surg Pathol 28(9): 1145-53.

This page last revised 9.10.2004.

©SMUHT/PW Bishop