Invasive breast carcinoma - IARC

Fig. 1.11 Invasive ductal carcinoma, not otherwise
specified. 84 year old patient, mastectomy specimen.
accepted internationally, but since 'ductal'
is still widely used the terms invasive
ductal carcinoma, ductal NOS or NST
are preferred terminology options.
Epidemiology
Ductal NOS carcinoma forms a large
proportion of mammary carcinomas and
its epidemiological characteristics are
similar to those of the group as a whole
(see epidemiology). It is the most common
'type' of invasive carcinoma of the
b reast comprising between 40% and
75% in published series {774}. This wide
range is possibly due to the lack of
application of strict criteria for inclusion
in the special types and also the fact that
some groups do not recognize tumours
with a combination of ductal NOS and
special type patterns as a separate
mixed category, preferring to include
them in the no special type (ductal NOS)
group.
Ductal NOS tumours, like all forms of
breast cancer, are rare below the age of
40 but the proportion of tumours classified
as such in young breast cancer
cases is in general similar to older cases
{1493}. There are no well recognized differences
in the frequency of breast cancer
type and proportion of ductal NOS
cancers related to many of the known
risk factors including geographical, cultural/lifestyle,
reproductive variables (see
aetiology). However, carcinomas developing
following diagnosis of conditions
such as atypical ductal hyperplasia and
lobular neoplasia, recognized to be
associated with increased risk include a
higher proportion of tumours of specific
type specifically tubular and classical
lobular carcinoma {2150}. Familial breast
cancer cases associated with BRCA1
mutations are commonly of ductal NOS
type but have medullary carcinoma like
features, exhibiting higher mitotic counts,
a greater proportion of the tumour with a
continuous pushing margin, and more
lymphocytic infiltration than sporadic
cancers {1572}. Cancers associated with
BRCA2 mutations are also often of ductal
NOS type but exhibit a high score for
tubule formation (fewer tubules), a higher
proportion of the tumour perimeter
with a continuous pushing margin and a
lower mitotic count than sporadic cancers
{1572}.
Macroscopy
These tumours have no specific macroscopical
features. There is a marked variation
in size from under 10 mm to over
100 mm. They can have an irregular, stellate
outline or nodular configuration. The
tumour edge is usually moderately or ill
defined and lacks sharp circumscription.
Classically, ductal NOS carcinomas are
firm or even hard on palpation, and may
have a curious 'gritty' feel when cut with
a knife. The cut surface is usually greywhite
with yellow streaks.
Histopathology
The morphological features vary considerably
from case to case and there is frequently
a lack of the regularity of structure
associated with the tumours of specific
type. Architecturally the tumour cells
may be arranged in cords, clusters and
trabeculae whilst some tumours are
characterized by a predominantly solid
or syncytial infiltrative pattern with little
associated stroma. In a proportion of
cases glandular differentiation may be
apparent as tubular structures with central
lumina in tumour cell gro u p s .
Occasionally, areas with single file infiltration
or targetoid features are seen but
these lack the cytomorphological characteristics
of invasive lobular carcinoma.
The carcinoma cells also have a variable
appearance. The cytoplasm is often
abundant and eosinophilic. Nuclei may
be regular, uniform or highly pleomorphic
with prominent, often multiple, nucleoli,
mitotic activity may be virtually absent or
extensive. In up to 80% of cases foci of
associated ductal carcinoma in situ
(DCIS) will be present {147,2874}.
Associated DCIS is often of high grade
comedo type, but all other patterns may
be seen.
Some recognize a subtype of ductal
NOS carcinoma, infiltrating ductal carcinoma
with extensive in situ component.
The stromal component is extremely variable.
There may be a highly cellular
fibroblastic proliferation, a scanty connective
tissue element or marked hyalinisation.
Foci of elastosis may also be
present, in a periductal or perivenous
distribution. Focal necrosis may be pres-
A
B
Fig. 1.12 A Infiltrating ductal carcinoma, grade I. B Infiltrating ductal carcinoma, grade II. C Invasive ductal NOS carcinoma, grade III with no evidence of glandular differentiation.Note
the presence of numerous cells in mitosis, with some abnormal mitotic figures present.
C
20 Tumours of the breast