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Cytokeratin 20 (CK20, K20)

Reviewer: Kara Hamilton, M.S., Nat Pernick, M.D. (see Reviewers page)
Revised: 20 July 2013, last major update June 2009
Copyright: (c) 2002-2013, PathologyOutlines.com, Inc.


Uses by pathologists

Micro images

Anal glands are CK20- (fig 1C) but rectal adenocarcinoma is CK20+ (fig 2)

Barretts: classic and non classic staining patterns

Cervical adenocarcinoma: intestinal type is CK20- (fig 1E)

Colonic adenocarcinoma: #1-well differentiated; #2-poorly differentiated; #3-metastatic; #4-primary (fig G) and metastatic to lung (fig H)

Colonic medullary carcinoma (fig 4)

Craniopharyngioma is CK20- (fig 1C); Rathke cleft cyst is CK20+ (fig 2C); pituitary gland pars intermedia is CK20+ (fig 3C)

Gastric epithelium (normal)

Gastric carcinoma (poorly differentiated, fig 4a)

Intestinal metaplasia of the urinary bladder (fig c); typical cystitis glandularis (fig h)

Lung: nonmucinous bronchioloalveolar carcinoma is CK20- (fig 1D)

Lung: mucinous bronchioloalveolar carcinoma is CK20+ (fig 2D)

Merkel cell carcinoma; #3-FNA

Pancreatic carcinoma (fig B, D and F)

Pancreatic ductal carcinoma is CK20- (fig 1f); adenocarcinoma of gallbladder is CK20+

PanIN lesions: CK20+ in grades 1, 2 and 3

Prostatic adenocarcinoma; #2 with positive staining of verumontanum

Rectal adenocarcinoma (fig 2)

Sinonasal adenocarcinoma: intestinal type (fig 4B)

Testicular mucinous cystadenoma is CK20+ (fig 3a), but ovarian tumor is CK20- (fig 5a)

Tubular adenocarcinoma

Urothelium (normal, fig 1B)

Urothelial papilloma (fig 2C)

Urothelial papillary neoplasm of LMP (fig 3C)

Urothelial CIS is diffusely CK20+ (fig B)

Urothelial carcinoma: #1-high grade; #2-papillary-high grade (fig 5C); #3-papillary-low grade (fig 4C); #4-CK20+ primary and nodal metastasis; #5 (CK20-, uncommon)

Contributed by Leica Microsystems, Biosystems Division:

Colon (normal): cytokeratin 20 (PW31) with intense cytoplasmic staining

Positive staining - normal

Positive staining - not carcinoma

Positive staining - carcinoma

Negative staining

End of Stains > Cytokeratin 20 (CK20, K20)

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