abstract
Ovarian endometrioid carcinomas (OEC) of low grade have characteristic
morphologic features,
but high-grade tumors can mimic high-grade serous
and undifferentiated carcinomas. We reviewed tumors initially diagnosed
as OEC to determine whether a combination of pathologic and
immunohistochemical features can improve histologic subclassification.
Tumors initially diagnosed as OEC were reviewed using World Health
Organization criteria. We also noted the presence of associated
confirmatory endometrioid features (CEFs): (i) squamous metaplasia; (ii)
endometriosis; (iii) adenofibromatous background; and (iv) borderline
endometrioid or mixed Mullerian component. A tissue microarray was
constructed from 27 representative tumors with CEF and 14 without CEF,
and sections were stained for WT-1, p16, and p53. Of 109 tumors
initially diagnosed as OEC, 76 (70%) tumors were classified as OEC. The
median patient age was 55 years, and 75% of patients were younger than
60 years. Ninety-two percent presented with disease confined to the
pelvis, and 87% of tumors were unilateral. The median tumor size was
11.8 cm. Only 3% of tumors were high grade (grade 3of 3). Eighty percent
of cases had at least 1 CEF, and 59% had at least 2 CEFs. Eleven
percent overexpressed p16, 0% overexpressed p53, and 3% expressed WT-1.
Only 10% of patients died of disease at last follow-up.
Thirty-three
(33) tumors, or 30% of tumors originally classified as endometrioid,
were reclassified as serous carcinoma (OSC). The median patient age was
54.5 years, and 59% of patients were younger than 60 years of age. Only
27% had disease confined to the pelvis at presentation, 52% of tumors
were unilateral, and the median tumor size was 8 cm. Associated squamous
differentiation, endometrioid adenofibroma, and endometrioid or mixed
Mullerian borderline tumor (CEFs) were not present in any case, but 6%
of patients had endometriosis. Approximately one half of the
reclassified OSC demonstrated SET-pattern morphology (combinations of
glandular, cribriform, solid, and transitional cell-like architecture)
and were immunophenotypically indistinguishable from OSCs with papillary
architecture. Sixty percent of OSC overexpressed p16, 50% overexpressed
p53, and 82% expressed WT-1. At last follow-up, 52% had died of
disease. Compared with OSC, OEC patients more frequently presented below
60 years of age (P=0.046), had low-stage tumors (P<0.001), were more
frequently unilateral (P<0.001), more frequently had synchronous
endometrial endometrioid carcinomas (P<0.001); and had no evidence of
disease at last follow-up (P<0.001). Their tumors were of lower
grade (P<0.001), had more CEFs (P<0.001), and less frequently
overexpressed p16 and p53 (P=0.003 and P<0.001, respectively) and
less frequently expressed WT-1 (P<0.001). This analysis emphasizes
the diagnostic value of CEFs, the presence of a low-grade gland-forming
endometrioid component, and WT-1 negativity, as valid, clinically
relevant criteria for a diagnosis of OEC. Glandular and/or cribriform
architecture alone may be seen in both OECs and OSCs and are therefore
not informative of diagnosis.
Further study is needed to elaborate the
characteristics of the exceedingly rare high-grade OEC.
