Stains - Alpha feto-protein (AFP)

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Stains

Alpha feto-protein (AFP)

Reviewer: Nat Pernick, M.D. (see Reviewers page)
Revised: 13 December 2011, last major update December 2011
Copyright: (c) 2002-2011, PathologyOutlines.com, Inc.

Definition
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● Major plasma protein of early fetus; present in fetal gut, liver and yolk sac (Wikipedia)

Uses by Pathologists
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Serum marker:
● Elevated in maternal serum or amniotic fluid ( > 2.5 multiples of median at a specified gestational age) if fetal developmental anomalies
● Also a serum tumor marker elevated in patients with hepatoblastoma (eMedicine), hepatocellular carcinoma, hepatoid adenocarcinoma, testicular cancer (other than pure seminoma) and yolk sac tumor
● High levels are poor prognostic marker for hepatocellular carcinoma (J Gastroenterol Hepatol 2008;23:e189)

Immunostain:
● Somewhat sensitive and specific for hepatocellular carcinoma, hepatoid adenocarcinoma, germ cell tumors and particularly yolk sac tumor

Micro images
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Dysgerminoma - ovary (negative staining)

Hepatoid adenocarcinoma: left to right - bladder, gallbladder, lung

Liver - adult hepatic blastoma (fig B)

Yolk sac tumors (left to right) bladder/urachus (fig D), extragonal, testis

Yolk sac tumor arising in mature teratoma of liver

Positive staining - normal
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● Early fetal gut, hepatocytes, yolk sac

Positive staining - disease
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● Various sites: embryonal carcinoma, some extrahepatic carcinomas (Acta Cytol 2003;47:799), hepatoid adenocarcinoma (J Clin Pathol 1996;49:420, Int J Gynecol Cancer 2007;17:1150), teratomas (some), yolk sac tumor
● Liver: hepatoblastoma, hepatocellular carcinoma (60%, Mod Pathol 1997;10:686, Am J Surg Pathol 2002;26:978), infantile hemangioendothelioma (rare, Hum Pathol 2010;41:763)
● Ovary: some Sertoli-Leydig tumors (in hepatoid areas), yolk sac tumors (strong)
● Pancreas: acinar cell carcinoma (some, Anticancer Res 2005;25:1671), pancreatoblastoma (up to 68%, JOP 2007;8:55)

Negative staining
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● Hepatocellular carcinoma-diffuse cirrhosis-like variant (Am J Surg Pathol 2010;34:935)
● Cholangiocarcinoma, hepatocellular adenoma, seminoma

End of Stains > Alpha feto-protein (AFP)

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