Invasive breast carcinoma - IARC

tumours may superficially invade the
myometrium, but metastases have not
been reported. Invasion of myometrial
veins has also been described {514}.
Occasional cases have been focally
involved by adenocarcinoma, but the
association is probably incidental {1873}.
Adenomyoma including atypical
polypoid adenomyoma
Definition
A lesion composed of benign epithelial
(usually endometrial glands) and mesenchymal
components in which the mesenchymal
component is fibromyomatous
Atypical polypoid adenomyoma is a variant
of adenomyoma in which the glandular
component exhibits arc h i t e c t u r a l
complexity with or without cytological
atypia.
Epidemiology
Adenomyoma may occur at any age,
whereas atypical polypoid adenomyoma
characteristically occurs in premenopausal
women {1690,1801,3228}.
Macroscopy
Adenomyomas and atypical polypoid
adenomyomas usually are polypoid submucosal
lesions but may rarely be intramural
or subserosal {1002}. They have a
f i rm sectioned surface. Atypical polypoid
adenomyoma usually involves the
lower uterine segment or upper endoc
e r v i x .
Histopathology
Adenomyoma is composed of an admixt
u re of benign endometrial glands (there
may be minor foci of tubal, mucinous or
squamous epithelium) with minimal cytological
atypia and architectural complexity
embedded in a benign fibro m y o m a t o u s
mesenchyme. Often endometrial type
s t roma surrounds the endometrial glandular
component, and the former is in turn
s u r rounded by smooth muscle {1002}.
Atypical polypoid adenomyoma
In atypical polypoid adenomyoma the
glands characteristically show marked
a rchitectural complexity; there is no
endometrial type stroma around the dist
o rted glands. There is often also cytological
atypia that varies from mild to marked.
Foci may be present that arc h i t e c t u r a l l y
resemble well diff e rentiated adenocarc i-
noma, and such tumours have been designated
"atypical polypoid adenomyoma
of low malignant potential" {1690}.
Extensive squamous or morular metaplasia
of the glandular elements, with or without
central necrosis, is a common finding.
The mesenchymal component is composed
of swirling and interlacing fascicles
of benign smooth muscle.
Differential diagnosis
It should be noted that many simple
endometrial polyps contain a minor component
of smooth muscle within the stroma;
however, this finding alone is not
s u fficient for the diagnosis of adenomyoma.
The designation adenomyoma has
also been used for a localized adenomyosis
that forms a discrete mass, but
such usage is confusing and not re c o m-
mended.
D i ff e rentiation from a well diff e re n t i a t e d
endometrioid adenocarcinoma invading
the myometrium may be difficult, especially
on a curettage or biopsy specimen.
H o w e v e r, the usual lack of pro n o u n c e d
cellular atypia and the absence of a stromal
desmoplastic response would be
against a diagnosis of adenocarc i n o m a .
Additional features against a diagnosis of
c a rcinoma are the usual youth of the
patient and the presence of norm a l
endometrial fragments in the sample.
Genetic susceptibility
Atypical polypoid adenomyomas may
occur in women with Tu rner syndro m e
{ 5 1 7 } .
Prognosis and predictive factors
Adenomyoma is generally cured by simple
polypectomy, but if associated with
myometrial adenomyosis, symptoms may
persist. Atypical polypoid adenomyoma
may re c u r, especially following incomplete
removal. In addition, superf i c i a l
myometrial infiltration is often identified in
h y s t e rectomy specimens, a finding that
may be more common in those cases with
marked glandular architectural complexity
{1690}. A small number of cases are
associated with an underlying endometrioid
adenocarcinoma with a transition zone
between the two components {1882,
2 8 1 3 } .
Mixed epithelial and mesenchymal tumours 249