Endometrial Carcinoma (Endometrioid)

Common sites:

Gross features:

• almost always exophytic
• shaggy, glistening, tan endometrium

Histologic features:

• endometrial stromal invasion (any one of the following):
• irregular or haphazard glandular pattern associated with an altered fibroblastic stroma (desmoplastic response)
• parallel, densely arranged fibroblasts
• more fibrosis than normal endometrial stroma
• disrupting the usual glandular pattern
• stromal cells are more spindle shaped, eosinophilic and wavy appearance (compressed by collagen)
• merging of glands without intervening stroma, creating a cribriform pattern
• extensive papillary pattern
• heavy lymphocytic infiltration surrounding the glands
• above features must involve half of a low-power field (2.1mm) (sample-size allowing)
• architectural grading (exclude squamous areas):
• grade 1 – up to 5% solid masses
• inappropriate nuclear atypia can increase the grade by 1
• grade 2 – up to 50% solid masses
• grade 3 – more than 50% solid masses
• villoglandular variant:
• fine, long, villi-like structures
• delicate fibrovascular stroma
• low-grade cytology
• mucinous microglandular variant:
• only mild nuclear atypia
• may be mistaken for microglandular hyperplasia in the cervix
• vimentin positive, CEA positive

Immunophenotype:

Marker:	Sensitivity:	Specificity:
Vimentin		Cervical adenoCA usually negative
ER / PR	FIGO grade 1 & 2	Cervical adenoCA usually negative
CEA (neg)	Mucinous microglandular variant is positive
P16 (neg)	most	Usually positive in cervical AdenoCA
P53 (patchy, weak) (not strong)	> 80% (FIGO grade 3 may be positive)	Strong positive in uterine serous carcinoma

Molecular features:

Other features:

• All variants of endometrioid adenocarcinoma tend to have good prognosis, only because their grade tends to be low.