Invasive breast carcinoma - IARC

serous and transitional cell carcinoma
and endometrioid and clear cell.
Grading
The least diff e rentiated component
determines the tumour grade.
Histogenesis
Endometriosis, occasionally with atypia,
is found in association with 53% of MEBT
{2496} and up to 50% of mixed clear cellendometrioid
tumours {2511}. Some
cases show a transition from endometriosis
to neoplastic epithelium.
Somatic genetics
It is impossible to make broad statements,
as studies are limited to a few
cases. LOH on chromosome 17, common
in serous tumours, has been found
in two of five mixed endometrioid-serous
tumours {959}. PTEN mutation, which has
been associated with the endometrioid
type, has also been noted in a mixed
mucinous-endometrioid tumour {2075}.
KRAS mutations, an early event in mucinous
tumours, have been noted in three
mixed Brenner-mucinous tumours {589}.
The mucinous cystadenocarcinoma and
B renner tumour components share d
amplification of 12q 14-21 in one MET,
suggesting clonal relatedness {2207}.
Prognosis and predictive factors
The behaviour of MEBT is similar to that of
endocervical-like mucinous bord e r l i n e
tumours. The dominant cell type generally
dictates behaviour. An exception is
mixed endometrioid and serous carcinoma,
which, even when the serous component
is minor, behaves more aggressively
than pure endometrioid carcinoma
and similarly to their serous counterpart.
Mixed endometrioid and serous carc i n o-
ma may recur as serous carc i n o m a
{2907}. This finding stresses the importance
of careful sampling of an
endometrioid cystadenocarcinoma to rule
out a mixed serous component.
Undifferentiated carcinoma
D e f i n i t i o n
A primary ovarian carcinoma with no diff
e rentiation or only small foci of diff e re n t i-
ation.
ICD-O code 8 0 2 0 / 3
E p i d e m i o l o g y
When applying the WHO criteria, appro x-
imately 4-5% of ovarian cancers are undiff
e rentiated carcinoma. The frequency of
u n d i ff e rentiated carcinoma was 4.1%
when defined as carcinomas with solid
a reas as the predominant component re p-
resenting over 50% of the tumour {2677}.
Clinical features
In the only large series the age of the
patients ranged from 39-72 (mean, 54
years) {2677}.
M a c r o s c o p y
M a c ro s c o p i c a l l y, undiff e rentiated carc i n o-
ma does not have specific features. The
tumours are predominantly solid, usually
with extensive areas of necrosis.
Tumour spread and staging
A c c o rding to FIGO, 6% of the patients are
d i s c o v e red in stage I, 3% are in stage II,
74% in stage III and 17% in stage IV; thus
91% of the tumours are discovered in
stages III and IV {2677}.
H i s t o p a t h o l o g y
H i s t o l o g i c a l l y, undiff e rentiated carc i n o m a
consists of solid groups of tumour cells
with numerous mitotic figures and significant
cytological atypia. Areas with a spindle
cell component, microcystic pattern
and focal vascular invasion can be seen.
It is unusual to see an undiff e re n t i a t e d
c a rcinoma without any other component
of müllerian carcinoma. Usually, areas of
high grade serous carcinoma are pre s e n t .
Foci of transitional cell carcinoma can
also be seen. Undiff e rentiated carc i n o m a
of the ovary does not have a specific
i m m u n o p h e n o t y p e .
D i ff e rential diagnosis
The main diff e rential diagnoses are granulosa
cell tumour of the adult type, transitional
cell carcinoma, poorly diff e re n t i a t e d
squamous cell carcinoma, small cell carcinoma
and metastatic undiff e re n t i a t e d
c a rcinoma.
Granulosa cell tumours may have a diffuse
pattern; however, it is unusual not to
have also areas with a trabecular pattern ,
Call-Exner bodies or areas showing sex
c o rds. In addition, undiff e rentiated carc i-
noma is a more anaplastic tumour with a
larger number of mitotic figures.
Transitional cell carcinomas might have
a reas of undiff e rentiated tumour; however,
either a trabecular pattern or large papillae
are always identified in the form e r.
Small cell carcinoma of the hyperc a l-
caemic type typically occurs in young
women and often contains follicle-like
s t r u c t u res. The cells of small cell carc i n o-
ma of the pulmonary type show nuclear
molding and have high nuclear to cytoplasmic
ratios.
F i n a l l y, metastatic undiff e rentiated carc i-
nomas are uniform tumours without papill
a ry areas.
All these diff e rential diagnoses can usually
be resolved when the tumour is well
sampled, and areas with a diff e re n t
m a c roscopic appearance are submitted.
Sampling will identify the diff e rent components
of the tumour that are characteristic
of primary ovarian lesions.
Prognosis and predictive factors
The five-year survival of patients with
u n d i ff e rentiated carcinoma is worse than
that of ovarian serous or transitional cell
c a rcinoma. Only 6% of these patients survive
for 5 years.
Unclassified adenocarcinoma
D e f i n i t i o n
A primary ovarian adenocarcinoma that
cannot be classified as one of the specific
types of müllerian adenocarc i n o m a
because it has overlapping features or is
not sufficiently diff e rentiated. These
tumours are uncommon.
ICD-O code 8 1 4 0 / 3
H i s t o p a t h o l o g y
Tumours in this category would include
well or moderately diff e rentiated tumours
with overlapping features such as a mucinous
tumour with cilia, or it might include
a less diff e rentiated tumour without distinctive
features of one of the mûllerian
types of adenocarcoma.
Prognosis and predictive factors
Since this group of tumours has not yet
been specifically studied, the prognosis is
not known.
Surface epithelial-stromal tumours 145