Table 4.

Proposed essential and desirable diagnostic criteria for AFP-producing endometrial carcinomas.

	Essential	Desirable
AFP-producing endometrial carcinoma	- Histomorphology consistent with carcinoma. Hepatoid morphology is allowed. - Positive IHC for AFP in ≥ 1% of tumor cells. - Absence of morphological patterns characteristic of yolk sac tumor but inconsistent with carcinoma. These include a reticular/microcystic pattern, Schiller-Duval bodies, and loose myxoid stroma.	- Positive IHC for SALL4. - Negative or non-diffuse IHC for ER, PR, PAX8 and CK7.
Hepatoid carcinoma of the endometrium	- Carcinoma resembling hepatocellular carcinoma.	- Positive IHC for AFP and/or SALL4. - Negative or non-diffuse IHC for ER, PR, PAX8 and CK7.
Fetal gut-like carcinoma of the endometrium	- Carcinoma resembling fetal gut epithelium (columnar epithelium with clear cytoplasm). - Exclusion of clear cell carcinoma and secretory variant of endometrioid carcinoma	- Positive IHC for AFP and/or SALL4. - Negative or non-diffuse IHC for ER, PR, PAX8 and CK7.
Non-clear glandular AFP-producing endometrial carcinoma	- Gland-forming adenocarcinoma without clear cells. - Positive IHC for AFP and/or SALL4.	- Negative or non-diffuse IHC for ER, PR, PAX8 and CK7.

AFP, α-fetoprotein; CK, cytokeratin; ER, estrogen receptor; IHC, immunohistochemistry; PR, progesterone receptor.