Invasive breast carcinoma - IARC

Tumours and related lesions
of the rete ovarii
F. Nogales
Definition
A varied group of benign and malignant
tumours and related lesions that originate
from the rete ovarii, a vestigial structure
present in the ovarian hilus and histologically
identical to its testicular homologue.
ICD-O codes
Rete ovarii adenocarcinoma 9110/3
Rete ovarii adenoma 9110/0
Clinical features
Most lesions are incidental findings in
postmenopausal patients. Sizeable cysts
and tumours manifest as pelvic masses.
Some cases may present with hormonal
symptoms due to concomitant hilus cell
hyperplasia or stromal luteinization in
adenomas.
Histopathology
The rete is an unusual site for any type of
pathology. In order to diagnose a lesion
as originating in the rete, it must be located
in the ovarian hilus and be composed
of cuboidal or columnar non-ciliated cells
arranged in retiform spaces. Areas of
normal rete and hilus cells should be
found in the vicinity of the tumour or show
a transition {2495}. Dilated areas and
cysts are the most frequent histological
finding, but a few solid pro l i f e r a t i v e
lesions have been reported.
The rete ovarii appears to be functionally
related to folliculogenesis {385}.
Although its embryology is not fully
understood, it is likely to be mesonephric
in origin. Recently, attention has been
focused on its morphology and
immunophenotype in order to find histogenetic
relationships with neoplasms of
uncertain origin such as tumours of probable
wolffian origin {682} and retiform
Sertoli-Leydig cell tumours {1904}, as
well as to differentiate it from endometriosis
{2494} and to identify new
mesonephric identity markers {2110}.
These studies show constant coexpression
of vimentin and cytokeratin and positivity
for CD10 {2110}, frequent positivity
for calretinin, inhibin and CA125 and isolated
positivity to A103 (melan-A) and
epithelial membrane antigen {605,1450,
2495,2792}.
Immunoprofile
Immunohistochemically, adenomas and
adenocarcinomas are positive for CAM
5.2, cytokeratin 19, CA125, CD10 and
occasionally for epithelial membrane
antigen and estrogen and progesterone
receptors.
Adenocarcinoma
A d e n o c a rcinoma of the rete ovarii is
Fig. 2.114 Carcinoma of the rete ovarii. The epithelial cells lining the papillae show marked atypia.
Fig. 2.115 Adenoma of the rete ovarii. Note the tubulopapillary architecture.
180 Tumours of the ovary and peritoneum