EURURO Vol. 72 No. 5

e139 860

Letter to the Editor
Re: Umberto Leone Roberti Maggiore, Simone Ferrero,
Massimo Candiani, et al. Bladder Endometriosis:
A Systematic Review of Pathogenesis, Diagnosis,
Treatment, Impact on Fertility, and Risk of Malignant
Transformation. Eur Urol 2017;71:790–807
Benign Mu¨llerian Lesions in the Urinary Bladder: Endome-
triosis, Endocervicosis, Endosalpingiosis, and Mu¨llerianosis
We read with interest the paper by Leone Roberti
Maggiore et al [1] published in a recent issue of European
Urology. The authors reviewed available knowledge on
bladder endometriosis (BE) and provided physicians with
guidance on the management of this condition. The authors
pointed out that ‘‘BE is defined as the presence of
endometrial glands and stroma in the detrusor muscle’’
and ‘‘the potential risk of malignant transformation since
this phenomenon is exceedingly rare’’ [1].
1. Bladder lesions comprising mu¨ llerian-derived
tissue
From a morphological point of view, BE is part of a wide
spectrum of lesions comprising mu¨ llerian-derived tissue.
Benign lesions include not only endometriosis but also
endocervicosis, endosalpingiosis, andmu¨ llerianosis [2]. These
lesions can involve all the components of the bladder wall,
from the mucosa to the serosa, and are typically centered in
the muscularis propria (detrusor). There are exceedingly rare
malignant mu¨ llerian lesions that can complicate a benign
mu¨ llerian lesion, such as BE. Potentially any formofmu¨ llerian
neoplasia that may complicate endometriosis, as observed
more commonly elsewhere, is a potential finding in the
urinary bladder, including mu¨ llerian-type clear cell carcino-
ma, endometrioid carcinoma, and mu¨ llerian adenosarcoma.
In addition, mu¨ llerian-like lesions can be observed in the
bladder, including a mu¨ llerian-like appearance in urothelial
neoplasia, urachal lesions with mu¨ llerian-like features, and
secondary mu¨ llerian neoplasia [3].
2. Endometriosis
The urinary bladder is involved in approximately 1% of
women with endometriosis. It is the most common location
of urinary tract involvement of this disease [4,5]. It can also
be seen in the ureter and less commonly in the urethra or
kidney [6]. Approximately 50% of these patients have a
previous history of pelvic surgery, such as cesarean section.
In up to 12% of cases there is no evidence of endometriosis
outside the bladder [4,5] . Rare cases of BE have been
observed in men with prostate adenocarcinoma treated
with estrogen therapy. The histological features of endo-
metriosis—endometrial glands and stroma —are so
distinctive that confusion with other mu¨ llerian glandular
lesions should not be an issue. The glands are lined by
cuboidal cells with the same changes seen in the normal
endometrium, depending on the phase of the cycle,
including decidual reaction (ie, decidualized vesical endo-
metriosis) and Arias-Srella reaction. The endometriotic
stroma contains foamy histiocytes with hemosiderin and
inflammatory cells, or can show elastosis. Any of the
common to rare features of endometriosis observed
elsewhere can be seen in the bladder [4,5].
Malignant tumors, in particular clear cell and endome-
trioid carcinoma, have arisen in association with BE
[4,5,7,8]. In such cases the glands show typically a more
complex pattern and architecture, with crowding (back-to-
back glands without intervening stroma) and cribriform
growth. Cytological atypia is prominent. There is desmo-
plastic reaction, in contrast to the endometrial stroma seen
in BE. Clear cell carcinoma with glandular morphology can
mimic a very similar type occurring on a background of
urothelial carcinoma, a neoplasm that can have clear cells.
The presence of unequivocal urothelial carcinoma and
immunohistochemistry can have a role in the differential
diagnosis [4,5].
3. Endocervicosis
Endocervicosis, a benign glandular lesion, involves the
urinary bladder as well as the outer wall of the uterine
cervix, vagina, paracervical connective tissue, pelvic perito-
neum, and pelvic lymph nodes in female patients of
reproductive age [4,5] . The most common location of the
glands, which are irregular in shape and size, is the posterior
wall of the bladder, centered in the detrusor (muscularis
propria) with extension to the subepithelial connective
tissue and bladder serosa. The lesion is composed of glands
ava ilable at
journal homepage:
DOI of original article: .
0302-2838/# 2017 European Association of Urology. Published by Elsevier B.V. All rights reserved.