Invasive breast carcinoma - IARC

Differential diagnosis
The much more common situation of a
cervical squamous cell carcinoma extending
into the endometrium must be excluded.
Predominantly squamous diff e re n t i a-
tion of an endometrioid adenocarc i n o m a
must also be excluded before making the
diagnosis of primary pure squamous cell
c a rcinoma of the endometrium.
Prognosis and predictive factors
The prognosis of most squamous cell
carcinomas of the endometrium is rather
poor, although the verrucous variant may
be more favourable.
Transitional cell carcinoma
Fig. 4.11 Clear cell adenocarcinoma of the endometrium. The tumour has a predominantly solid pattern with
occasional poorly formed tubules. The cytoplasm is clear, and cell walls are distinct.
eosinophilic (oncocytic) cytoplasm rather
than the more characteristic clear cytoplasm
{2258,2678}. This cell type may
comprise the entire tumour and make it
difficult to recognize as a clear cell adenocarcinoma.
Endometrial clear cell adenocarcinomas
are not graded.
Serous endometrial intraepithelial carcinoma
may also be seen in association
with clear cell adenocarcinoma, and the
associated benign endometrium is generally
atrophic rather than hyperplastic.
Prognosis and predictive factors
Patients with clear cell adenocarcinoma
are frequently diagnosed in advanced
clinical stages, and, thus, have a poor
p rognosis {24,400,1595,3003}. On the
other hand, clear cell adenocarcinoma
limited to the uterine corpus has a considerably
better prognosis than serous
adenocarcinoma of the same stage.
Mixed adenocarcinoma
Definition
Mixed adenocarcinoma is a tumour composed
of an admixture of a type I
(endometrioid carcinoma, including its
variants, or mucinous carcinoma) and a
type II carcinoma (serous or clear cell) in
which the minor type must comprise at
least 10% of the total volume of the
tumour. The percentage of the minor
component should be stated in the
pathology report. It is generally accepted
that 25% or more of a type II tumour
implies a poor prognosis, although the
significance of lesser proportions is not
well understood {2646,2691}.
Squamous cell carcinoma
Definition
A primary carcinoma of the endometrium
composed of squamous cells of varying
degrees of differentiation.
Epidemiology
Squamous cell carcinoma of the
endometrium is uncommon; only about
seventy cases have been re p o rt e d
{2397}.
Clinical features
Squamous cell carcinoma of the
endometrium usually occurs in postmenopausal
women and is often associated
with cervical stenosis and pyometra.
Histopathology
Its histological appearance is essentially
identical to that of squamous cell carcinoma
of the cervix and similarly includes
a rare verrucous variant {2654}.
Definition
A carcinoma in which 90% or more is
composed of cells resembling urothelial
transitional cells. Lesser quantities of
transitional cell diff e rentiation would
qualify the tumour as a mixed carcinoma
with transitional cell differentiation.
Epidemiology
Transitional cell diff e rentiation in
endometrial carcinomas is extre m e l y
uncommon with fewer than 15 cases
reported {1554,1669}. Among patients
with known racial origin, 50% are non-
White (African, Hispanic, or Asian). The
median age is 61.6 years (range 41-83
years).
Clinical features
The main complaint at presentation is
uterine bleeding.
Macroscopy
The tumours are often polypoid or papill
a ry with a mean size of 3.5 cm.
Infiltration of the myometrium is apparent
in some cases.
Histopathology
The transitional cell component is often
grade 2 or 3 and assumes a papillary
configuration. It is always admixed with
another type of carcinoma, most often
endometrioid, but it may be clear cell or
s e rous. HPV-associated koilocytotic
changes occur rarely. Only the transitional
cell component invades the
myometrum deeply {1669}. All endometrial
transitional cell carcinomas are negative
for cytokeratin 20 (CK20), but half
a re positive for cytokeratin 7 (CK7)
{1554,1669}.
Differential diagnosis
The diff e rential diagnosis includes
metastatic transitional cell carcinoma fro m
226 Tumours of the uterine corpus