Invasive breast carcinoma - IARC

Table 4.01
Grading of type I (endometrioid and mucinous)
endometrial adenocarcinoma.
– Grade 1: ≤ 5% non-squamous, non-morular
growth pattern
– Grade 2: 6-50% non-squamous, non-morular
growth pattern
– Grade 3: > 50% non-squamous, non-morular
growth pattern
Note: Squamous/morular components are
excluded from grading. Bizarre nuclear atypia
should raise the grade by one (i.e. from 1 to 2 or
2 to 3) but may also signify type II differentiation.
noma or may coexist with the usual
endometrioid pattern within a single
tumour.
Ciliated cell variant
Although occasional ciliated cells may
be seen in many endometrioid adenocarcinomas,
the diagnosis of the ciliated cell
variant is made only when ciliated cells
line the majority of the malignant glands.
Defined in this manner, this is a rare variant,
and the glands often have a strong
resemblance to tubal epithelium.
Mucinous adenocarcinoma
Definition
A primary adenocarcinoma of the
endometrium in which most of the tumour
cells contain prominent intracytoplasmic
mucin.
Epidemiology
Mucinous adenocarcinoma comprises
up to 9% of all cases of surgical stage I
endometrial carcinoma {2454}. However,
in most published series it is a relatively
r a re type of endometrial carc i n o m a
{1842}.
Histopathology
Both endometrioid and clear cell adenocarcinomas
may have large amounts of
intraluminal mucin, but only mucinous
a d e n o c a rcinoma contains the mucin
within the cytoplasm. The mucin is usually
easily visible with hematoxylin and
eosin staining but may also be demonstrated
with a mucicarmine or other
mucin stain.
Variants
Some mucinous adenocarcinomas have
a microglandular pattern and may be difficult
to distinguish from microglandular
hyperplasia of the endocervix in a biopsy
specimen {2066}. These neoplasms
have been reported as microglandular
carcinomas {3224,3241}. Rare mucinous
a d e n o c a rcinomas of the endometrium
may show intestinal differentiation, containing
numerous goblet cells.
Differential diagnosis
The main differential diagnosis of the
usual endometrial mucinous adenocarcinoma
is with a primary mucinous adenocarcinoma
of the endocervix. The distinction
may be particularly difficult in a
biopsy or curettage specimen but is crucial
for therapy and may have to be
resolved by clinical and imaging studies.
Some studies have claimed that immunohistochemistry
is useful in determining
the site of origin of an adenocarcinoma in
such a specimen, with endometrial carcinomas
being vimentin and estro g e n
receptor-positive and carcinoembryonic
antigen-negative and the opposite findings
for endocervical adenocarcinomas
{3180}. Others have found, however, that
this distinction is based more on differentiation
(endometrioid vs. mucinous) than
on site of origin {1393}.
Fig. 4.05 Well differentiated endometrioid adenocarcinoma,
villoglandular variant. Villous fronds
have delicate central cores and are lined by cells
with stratified nuclei.
Grading
Mucinous adenocarcinomas are theoretically
graded in the same way as
endometrioid adenocarcinomas, but in
practice almost all of them are grade 1.
Prognosis and predictive factors
The prognosis appears to be similar to
that of other low grade endometrial aden
o c a rcinomas and thus is generally
favourable.
Serous adenocarcinoma
Definition and historical annotation
A primary adenocarcinoma of the
endometrium characterized by a complex
pattern of papillae with cellular budding
and not infrequently containing
psammoma bodies.
Although long recognized as a common
type of adenocarcinoma of the ovary,
serous adenocarcinoma was first characterized
as a common endometrial
tumour in the early 1980s {1186,1590}.
Clinical features
Serous carcinoma typifies the so-called
type II endometrial carcinoma, which dif-
Fig. 4.06 Mucinous adenocarcinoma of the
endometrium. All of the tumour cells in this field
contain voluminous intracytoplasmic mucin.
Fig. 4.07 Microglandular carcinoma. Atypia, mitoses
and the endometrial location distinguish this tumour
from endocervical microglandular hyperplasia.
Fig. 4.08 Mucinous metaplasia. Mucinous glands
are prominent, however, glandular crowding or
atypia is not present.
224 Tumours of the uterine corpus