1
same neoplasm.
Nearly all LGSCs arise in a background of
ovarian benign or borderline serous tumors.
Most HGSCs are believed to arise from a
precursor lesion, STIC (serous tubal intraepi-
thelial carcinoma), in the tubal mbriae.
New criteria for primary site assignment in
HGSC include:
- Fallopian tube: STIC present, or mucosal
HGSC present, or part or all of the fallopian
tube is inseparable from tubo-ovarian mass.
- Ovary: both fallopian tubes are separate from
ovarian mass, and no STIC or mucosal HGSC
present in either fallopian tube.
- Tubo-ovarian: fallopian tubes and ovaries are
unavailable for complete examination, and
pathologic ndings are consistent with
extrauterine HGSC.
- Peritoneal (exceedingly rare): both fallopian
tubes and ovaries are fully examined using a
SEE-FIM (Sectioning and Extensively
Examining the FIMbriated end) protocol,
and no gross or microscopic evidence of STIC
or HGSC present in either fallopian tube or
ovary.
- These criteria classify approximately 80% of
HGSCs as primary tubal.
Serous borderline tumor is the sole recom-
mended term:
- Obsolete terminology no longer recommend-
ed includes atypical proliferative serous
tumor, serous tumor of low malignant
potential, semimalignant serous tumor and
non-invasive LGSC / micropapillary serous
borderline tumor (the latter no longer consid-
ered denitionally synonymous with non-
invasive LGSC).
NON-SEROUS EPITHELIAL
TUMORS
The following terminology is no longer
recommended:
- Atypical proliferative tumor or tumor of low
malignant potential for all epithelial tumors
(mucinous, endometrioid, seromucinous,
clear cell, Brenner).
Issue 15 || September 2021
WHAT’S NEW
IN GYNECOLOGIC
PATHOLOGY 2021:
OVARY AND
FALLOPIAN TUBE
Gulisa Turashvili
1
and Ricardo Lastra
2
1
Department of Pathology and Laboratory Medicine,
Sinai Health System and University of Toronto, Toronto,
ON, Canada
2
Department of Pathology, University of Chicago Medical
Center, Chicago, IL, USA
Corresponding Author: Gulisa Turashvili, MD, PhD
Department of Pathology and Laboratory Medicine
Sinai Health System and University of Toronto
Toronto, Ontario, Canada
E-mail: Gulisa.Turashvili@sinaihealth.ca
ORCID
Gulisa Turashvili
https://orcid.org/0000-0001-6125-5865
Ricardo Lastra
https://orcid.org/0000-0003-0691-5685
Abstract
The 5th edition of the World Health Organiza-
tion (WHO) Classication of Female Genital
Tumors was published in 2020. Although the
classication of ovarian and fallopian tube
neoplasms is largely unchanged from the prior
(4th) edition, this newsletter compiles the most
important renements in these organ sites,
including serous and non-serous epithelial
tumors, and sex cord-stromal tumors.
SEROUS NEOPLASMS
The 4th edition divided serous carcinoma into
low grade (LGSC) and high grade (HGSC) vari-
ants.
LGSC and HGSC are best considered two
fundamentally different tumors based on their
distinct biology, rather than variants of the
SEROMUCINOUS CARCINOMA
Previously dened as a carcinoma composed
predominantly of serous and endocervical-type
mucinous epithelium, often with foci showing
clear cells, endometrioid or squamous differen-
tiation.
Now considered a subtype of endometrioid
adenocarcinoma with mucinous differentiation
(Fig. 1).
NEW VARIANTS OF EPITHELIAL
TUMORS
Mesonephric-like adenocarcinoma:
- Composed of multiple architectural patterns
(tubular, glandular/pseudoendometrioid,
ductal, papillary, solid), intraluminal eosino-
philic colloid-like material, dense or vesicular
chromatin, inconspicuous nucleoli and
nuclear crowding, and lacking squamous or
mucinous differentiation.
- Positive for GATA3, TTF1, CD10 (luminal)
and PAX8, and negative for hormone
receptors and WT1, with wild-type p53
expression.
- Usually unilateral and diagnosed at stage I in
postmenopausal women.
- May arise from paraovarian mesonephric
remnants or Müllerian carcinomas displaying
secondary mesonephric transdifferentiation.
- May be associated with endometriosis,
cystadenomas, adenobromas, borderline
tumors and LGSC.
Fig. 1. Endometrioid adenocarcinoma with mucinous
differentiation.
WHAT’S NEW
IN PATHOLOGY?
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