Invasive breast carcinoma - IARC

yet others at 90% {97,2147}. For pragmatic
reasons, a 90% purity re q u i re m e n t
o ffers a practical solution.
Tumours exhibiting between 50 and 90%
tubular growth pattern with other types
should be regarded as mixed type of
carcinoma (see Mixed type carcinomas).
Differential diagnosis
Sclerosing adenosis (SA) can be distinguished
from tubular carcinoma by its
overall lobular arc h i t e c t u re and the
marked compression and distortion of
the glandular structures. Myoepithelial
cells are always present in sclerosing
adenosis and can be highlighted by
immunostaining for actin. Similarly, a fully
retained basement membrane can be
shown by immunohistological staining for
collagen IV and laminin in tubules of SA.
Microglandular adenosis (MA) can be
more difficult to differentiate because of
the rather haphazard arrangement of the
tubules, and lack of myoepithelial cells in
the tubules. However, the tubules of MA
are more rounded and regular and often
contain colloid-like secretory material, at
least focally, compared to the often angulated
tubules of tubular carc i n o m a .
Furthermore a ring of basement membrane
is present around tubules of MA.
Complex sclerosing lesions/radial scars
have a typical arc h i t e c t u re with central
f i b rosis and elastosis containing a few
small, often distorted, tubular structures in
which myoepithelial cells can be demonstrated.
The surrounding glandular struct
u res show varying degrees of dilatation
and ductal epithelial hyperplasia.
Immunophenotype
Tubular carcinoma is nearly always
e s t rogen and pro g e s t e rone re c e p t o r
positive, has a low growth fraction, and
is ERBB2 and EGFR negative {691,
1 3 7 9 , 2 1 6 6 } .
Genetics
Tubular carcinomas of the breast have a
low frequency of genetic alterations
when compared to other types of bre a s t
c a rcinoma. Using LOH and CGH techniques,
alterations have been found
most frequently at chromosomes 16q
(loss), 1q (gain), 8p (loss), 3p FHIT
gene locus, and 11q ATM gene locus
{1754,1779,2476, 3046}. Of part i c u l a r
i n t e rest is the observation that other
sites of chromosomal alteration pre v i-
ously found at high levels in other types
Fig. 1.25 Invasive cribriform carcinoma. The haphazard distribution of irregularly shaped and angulated invasive
areas is in contrast with the rounded configuration of the ducts with cribriform DCIS on the left side of the field.
of breast cancer are not seen, which
implies that tubular carcinoma of the
b reast is genetically distinct.
Prognosis and predictive factors
Pure tubular carcinoma has an excellent
long term prognosis {409,410,552,771,
1829,2081,2224} which in some series is
similar to age matched women without
breast cancer {691}. Recurrence following
mastectomy or breast conservation
treatment is rare and localized tubular
carcinomas are considered to be ideal
candidates for breast conservation techniques.
Following breast conservation,
the risk of local recurrence is so low that
some centres consider adjuvant radiotherapy
unnecessary. Axillary node
metastases occur infrequently, and when
observed rarely involve more than one
low axillary lymph node. There is little
adverse effect of node positivity in tubular
carcinoma {691,1471} and the use of
systemic adjuvant therapy and axillary
node dissection are considered unnecessary
by some groups {691,2166}.
Invasive cribriform carcinoma
Definition
An invasive carcinoma with an excellent
prognosis that grows in a cribriform pattern
similar to that seen in intraductal
cribriform carcinoma; a minor (90%) of an invasive cribriform patt
e rn. The tumour is arranged as invasive
islands, often angulated, in which
well defined spaces are formed by
a rches of cells (a sieve-like or cribrif
o rm pattern). Apical snouts are a re g-
ular feature. The tumour cells are small
and show a low or moderate degree of
nuclear pleomorphism. Mitoses are
r a re. A prominent, reactive appearing,
f i b roblastic stroma is present in many
ICC. Intraductal carcinoma, generally
of the cribriform type, is observed in as
many as 80% of cases {2148}. Axillary
lymph node metastases occur in 14.3%
{2148}, the cribriform pattern being
retained at these sites. Lesions showing
a predominantly cribriform arrange-
Invasive breast cancer
27