Table 1 Distinction between poorly differential serous and poorly differentiated endometrioid adenocarcinoma

Morphology	Serous	Endometrioid
Glandular spaces	Slit-like	Round, punched-out
Psammoma bodies	Common	Rare
Tumour giant cells	Common	Rare
Papillae	Small, complex with budding	Longer and broader
Adenofibromatous growth pattern	Rare	Common
Squamous elements	Rare	Common
Endometriosis	Rare	Common

Immunohistochemistry
WT1	Diffuse positive	Negative or focally positive
p53	Diffuse positive	Negative, focally or diffuse positive
p16	Diffuse positive	Negative or focally positive
Vimentin	Negative	Sometimes positive
β-Catenin	Membranous staining	Membranous and, in some cases, nuclear positivity