Home > A. Molecular pathology > KRT7

KRT7

HGNC:6445 MIM.148059

Monday 9 June 2003

cytokeratin-7, keratin-7, CK7; molecular weight 54 kDa

PO

Definition: CK7 is a type II keratin of simple nonkeratinizing epithelia. CK7is expressed in breast, lung, ovary and urothelium, but usually NOT in GI or stratified squamous epithelium.

CK7 expression in normal cells

- breast
- lung
- ovary
- urothelium
- biliary epithelial cells
- Anal glands and anal transition zone (Arch Pathol Lab Med 2001;125:1074)
- Bile ducts (Exp Cell Res 1987;170:235)
- Breast
- Cervical glands
- Endometrium
- Fallopian tube
- Fetal cells in transcervical mucus (J Obstet Gynaecol Res 2005;31:500)
- Gallbladder
- Kidney collecting ducts
- Lung
- Mesothelium
- Ovarian epithelium (Am J Pathol 1991;138:455)
- Pancreatic ducts (J Pathol 1998;184:234)
- Salivary gland acini (Mod Pathol 2004;17:803), intercalated ducts and intercalated duct lesions (Am J Surg Pathol 2009;33:1322)
- Thyroid epithelium
- Toker cells (Am J Dermatopathol 2005;27:185)
- Trophoblast (J Immunol Methods 2004;286:21)
- Urothelium (Eur J Cell Biol 2004;83:27)

CK7 expression in benign lesions

- Cystitis glandularis (bladder) of usual type (intestinal type is CK7-)
- Colonic serrated adenoma (Dig Dis Sci 2005;50:1741)
- Ependymoma: extra-axial (80%) versus CNS (10%, Am J Surg Pathol 2008;32:710)
- Esophagus-Barrett’s: strong diffuse CK7+ surface and crypt epithelium, strong CK20+ surface and superficial crypt staining; interpretation is affected by fixative (Hum Pathol 2005;36:58, but see Mod Pathol 2002;15:611); pattern may help distinguish short segment Barrett’s from cardiac intestinal metaplasia (World J Gastroenterol 2005;11:6360)
- Eye: Fuchs endothelial dystrophy (Cornea 2006;25:956)
- Liver: bile duct adenoma, mesenchymal hamartoma, chronic allograft rejection (Am J Clin Pathol 2011;135:238). perivenular hepatocytes associated with cholestatic chemistry profile and heart failure (Mod Pathol 2010;23:1650)
- Lymph nodes: individual / clusters of neuroendocrine cells (Am J Surg Pathol 2010;34:1701)
- Nephrogenic adenoma of GU tract (Am J Surg Pathol 2009;33:1654)
- Pancreas: lymphoepithelial cyst (Mod Pathol 2010;23:1467)
- Salivary gland oncocytoma (Laryngoscope 2005;115:1097)

CK7 expression in malignant tumors

- cutaneous Paget disease (#9500217#, #9331290#)

  • Intraepidermal cytokeratin 7 expression is not restricted to Paget cells but is also seen in Toker cells and Merkel cells. (#9989849#)

- mucinous cystadenocarcinoma of the breast

  • All cases stain positively with cytokeratin 7 (CK7) but were negative with cytokeratin 20 (CK20).

- papilary renal cell carcinoma
- benign proliferative nipple duct lesions (#10555003#)

- colorectal adenocarcinoma

  • The most common immunophenotype of colorectal adenocarcinoma is positivity for CK20 and negativity for CK7, which is a relatively specific staining pattern for colorectal origin.
  • However, up to 20% of the tumors may exhibit a CK7-positive/CK20 negative or CK7-negative/CK20-negative staining pattern.
  • It has been suggested that reduced or absent CK20 expression in colorectal carcinoma is associated with MSI-H.
  • Colon adenocarcinoma related to ulcerative colitis (59%, Virchows Arch 2006;448:756)

- mucinous adenocarcinomas from

  • ampulla
  • biliary tree
  • esophagus
  • pancreas
  • stomach (93%, Am J Surg Pathol 2011;35:1830)
  • colon / rectum / anus (only 19% are CK7+, most from rectum/anus, Am J Surg Pathol 2011;35:1830)

- other digestive tumors

  • anal duct carcinoma (Hum Pathol 2011 Aug 3 [Epub ahead of print])
  • appendiceal epithelial neoplasms (benign and malignant-33%, Hum Pathol 2005;36:1217)

- head and neck tumors

  • basaloid squamous cell carcinoma of Waldeyer’s ring (Hum Pathol 2000;31:1096)

- bile duct carcinoma (90%, Hum Pathol 2005;36:1226)
- bladder adenocarcinoma (63%, Appl Immunohistochem Mol Morphol 2005;13:358)
- mammary carcinoma (Ann Diagn Pathol 1999;3:350)
- carcinoid tumors (GI, 11%, Hum Pathol 2001;32:1087)
- cervical adenocarcinoma (Am J Clin Pathol 2009;132:531)

- Germ cell tumors at various sites (variable, but usually negative)

- renal cell carcinoma

  • chromophobe (Am J Clin Pathol 2007;127:225)
  • clear cell tubulopapillary (Am J Surg Pathol 2010;34:1608)
  • collecting duct, papillary (Am J Surg Pathol 2011;35:949)

- Liver: hepatocellular carcinoma (10-34% positive, Mod Pathol 2006;19:460)

  • particularly scirrhous / fibrolamellar type (Histopathology 2005;47:382) or age 30 or younger, Am J Clin Pathol 2005;124:512)

- pulmonary adenocarcinoma-94% vs. squamous cell-60% (Hum Pathol 2006;37:542, Am J Surg Pathol 2011;35:15)

- Merkel cell carcinoma (50%, J Eur Acad Dermatol Venereol 2005;19:546)
- Mesothelioma, including with rhabdoid features (Mod Pathol 2006;19:373)

- Ovarian carcinoma (Mod Pathol 2006;19:1421)

  • but mucinous carcinoma with pseudomyxoma ovarii (suggesting teratomatous derivation) are CK7- (Am J Surg Pathol 2007;31:854);
  • ovarian carcinoids (24%)
  • Sertoli cell tumors (13%, Am J Surg Pathol 2007;31:255)

- Paget’s cells (breast, anal, vulvar, esophageal, but not vulvar secondary to anorectal carcinoma, Am J Surg Pathol 1998;22:170-perianal, Hum Pathol 2002;33:545-vulvar, Am J Surg Pathol 2008;32:1068-esphageal)
- Pancreatic carcinoma including intestinal type (Ann Diagn Pathol 2007;11:3)
- Pseudomyxoma peritonei (almost all cases have variable positivity, Histopathology 2006;49:381)
- Salivary gland: carcinoma (100%, Pathol Int 2005;55:386), lymphadenoma (Mod Pathol 2011 Sep 2 [Epub ahead of print])
- Sinonasal adenocarcinoma (most, Ann Otol Rhinol Laryngol 2006;115:59)
- Small intestinal adenocarcinoma (Am J Surg Pathol 2004;28:1499)
- Synovial sarcoma (many, Mod Pathol 2006;19:659)
- Urothelial carcinoma (87%), urothelial carcinoma in situ of the bladder with glandular differentiation (Hum Pathol 2011;42:1653)
- Uterus: endometrioid adenocarcinoma (100%), endocervical (50%, Int J Gynecol Pathol 2012;31:57); most mucinous tumors (Appl Immunohistochem Mol Morphol 2009;17:8)

Negative for CK7 detection

- Adrenocortical carcinoma
- Cervical squamous epithelium
- Endometrial stromal sarcoma (Hum Pathol 2008;39:1459)
- GI epithelium (normal)
- GI carcinomas-nonmucinous (but see exceptions above)
- Hepatocytes; hepatoid adenocarcinoma
- Kidney

  • normal tubules
  • carcinoid (may have focal staining) (Am J Surg Pathol 2007;31:1539)
  • clear cell carcinoma (usually)
  • oncocytoma

- Nasal cavity: nonkeratinizing nasopharyngeal carcinoma-differentiated and undifferentiated

- Pituitary adenomas (usually, Endocr Pathol 2005;16:201)
- Prostate adenocarcinoma (Mod Pathol 2000;13:962), but prostatic mucin producing urothelial-type carcinoma is usually CK7+ (83%, Am J Surg Pathol 2007;31:1323)
- Skin (squamous epithelium)
- Tongue
- Yolk sac tumor (Am J Surg Pathol 2004;28:1499)

CK7 /CK20 coupled immunochemistry

- CK7+ / CK20+ tumors

  • carcinomas of bile duct (extrahepatic / gallbladder, often, Pathol Res Pract 2003;199:65)
  • lung-mucinous bronchioloalveolar (Am J Clin Pathol 2004;122:421)
  • pancreas (Cancer 2006;106:693, but see Arch Pathol Lab Med 2000;124:1196)
  • urothelium (often, Arch Pathol Lab Med 2001;125:921, Hum Pathol 2002;33:1136)
  • primary mucinous tumors of ovary (74%)
  • upper GI tract (78%)
  • endocervix (88%, Am J Surg Pathol 2006;30:1130)

- CK7+ / CK20- tumors

  • carcinomas of bile duct (intrahepatic, Pathol Res Pract 2003;199:65)
  • breast (Ann Diagn Pathol 1999;3:350)
  • endocervical and endometrial adenocarcinoma (Int J Gynecol Pathol 2002;21:4)
  • esophagus (distal, Am J Surg Pathol 2002;26:1213)
  • lung (not mucinous bronchioloalveolar, BMC Cancer 2006;6:31)
  • salivary gland (Pathol Int 2005;55:386)
  • thyroid (Appl Immunohistochem Mol Morphol 2000;8:189); mesothelioma (Cancer 2001;92:2727)

- CK7- / CK20+ tumors

  • carcinoma of colon (particularly early stage, Hum Pathol 2005;36:275)
  • primary mucinous tumors of lower GI tract (79%, Am J Surg Pathol 2006;30:1130)
  • primary bladder adenocarcinoma (29%, Am J Surg Pathol 2001;25:1380)

- CK7- / CK20-

  • carcinoma of adrenal cortex
  • prostate (Mod Pathol 2000;13:962)

CK7 use in differential diagnostic

- To distinguish primary lung carcinoma (CK7+ / CK20-) from metastatic colonic carcinoma to lung (CK7- / CK20+) (BMC Cancer 2006;6:31) + CDX2 labelling
- To distinguish adenocarcinoma of distal esophagus (CK7+ / CK19+: 90%, CK7+ / CK20-: 74%) from proximal stomach adenocarcinoma (CK7+ / CK19+: 44%, CK7+ / CK20-: 24%, Am J Surg Pathol 2002;26:1213)
- To distinguish chromophobe carcinoma (diffuse CK7+ staining) from oncocytoma (usually CK7-, Anal Quant Cytol Histol 2006;28:228)
- To help distinguish papillary renal cell carcinoma (CK7+) from metanephric adenoma (CK7-) (Mod Pathol 2006;19:218)
- To distinguish endometrioid carcinoma and clear cell carcinoma (CK7+) from yolk sac tumors (CK7-) (Am J Surg Pathol 2004;28:1499)

See also

- KRT19 (CK19)

References

- http://www.pathologyoutlines.com/topic/stainsck7.html

Breast cancer and mammary lesions

- Benign proliferative nipple duct lesions frequently contain CAM 5.2 and anti-cytokeratin 7 immunoreactive cells in the overlying epidermis. Zeng Z, Melamed J, Symmans PJ, Cangiarella JF, Shapiro RL, Peralta H, Symmans WF. Am J Surg Pathol. 1999 Nov;23(11):1349-55. PMID: #10555003#

- Mucinous cystadenocarcinoma of the breast. Koenig C, Tavassoli FA. Am J Surg Pathol. 1998 Jun;22(6):698-703. PMID: #9630176#

Paget disease

- Intraepidermal cytokeratin 7 expression is not restricted to Paget cells but is also seen in Toker cells and Merkel cells. Lundquist K, Kohler S, Rouse RV. Am J Surg Pathol. 1999 Feb;23(2):212-9. PMID: #9989849#

- Perianal Paget’s disease: a histologic and immunohistochemical study of 11 cases with and without associated rectal adenocarcinoma. Goldblum JR, Hart WR. Am J Surg Pathol. 1998 Feb;22(2):170-9. PMID: #9500217#

- Vulvar Paget’s disease: a clinicopathologic and immunohistochemical study of 19 cases. Goldblum JR, Hart WR. Am J Surg Pathol. 1997 Oct;21(10):1178-87. PMID: #9331290#

Renal cell carcinomas

- Renal cell carcinomas in children and young adults: increased incidence of papillary architecture and unique subtypes. Renshaw AA, Granter SR, Fletcher JA, Kozakewich HP, Corless CL, Perez-Atayde AR. Am J Surg Pathol. 1999 Jul;23(7):795-802. PMID: #10403302#

Portfolio

  • Cytokeratin-7 in ductular reaction
  • Cytokeratin-7 in ductular proliferation
  • Cytokeratin-7 in ductular proliferation
  • Cytokeratin-7 in ductular proliferation