Invasive breast carcinoma - IARC

evidence of neuroendocrine diff e re n t i a-
tion {2533}. These proteins are identifiable
by immunohistochemical and
immunoblot analysis. Poorly and moderately
diff e rentiated endocrine bre a s t
c a rcinomas of the alveolar subtype, in
general, express chromogranin A. The
mRNA specific for chromogranin A is
detectable by in situ hybridization technique
{2535}. About 50% of well or
moderately diff e rentiated tumours
e x p ress chromogranin B and A and
only 16% express synaptophysin
{2535}. A monoclonal antibody against
n e u rone-specific enolase (NSE) has
also been used and is expressed in
100% of small cell carcinomas of the
b reast {2662}, whereas chromogranin A
and synaptophysin are expressed in
about 50% of such cases. In addition,
20% of small cell mammary carc i n o m a s
e x p ress thyroid transcription factor- 1
(TTF-1) {2661}.
Immunodetection of pan-endocrine
markers may fail to recognize endocrine
tumours, which produce but do
not retain the specific antigen in the
cells. Estrogen (ER) and pro g e s t e ro n e
receptors (PR) are expressed in the
majority of tumour cells in well diff e re n-
tiated tumours {2535}, and in more than
50% of small cell carcinomas {2662}.
E x p ression of somatostatin re c e p t o r s
(SSR), a known feature of tumours
showing neuroendocrine diff e re n t i a t i o n ,
has been demonstrated in endocrine
b reast carcinomas as well {2169}.
U l t r a s t r u c t u r e
D i ff e rent types of dense core granules,
whose neuro s e c re t o ry nature is conf
i rmed by ultrastructural immunolocalization
of chromogranin A have been
identified by electron microscopy in
endocrine breast carcinomas {397}.
The presence of clear vesicles of presynaptic
type is correlated with the
e x p ression of synaptophysin.
Both dense core granules and mucin
vacuoles are present in neuro e n d o c r i n e
mucinous carcinomas {1265}.
G e n e t i c s
N e u roendocrine breast carc i n o m a s
have not been correlated to specific
gene mutations.
Postulated normal counterpart
A r g y rophilic and chromogranin A-re a c-
tive cells, located between the basal
myoepithelial and the luminal epithelial
cells, have been demonstrated in histologically
normal breast tissue surro u n d-
ing infiltrating and in situ neuro e n-
docrine breast carcinomas {382,1995,
2 5 4 2 , 2 9 5 6 } .
Prognosis and predictive factors
Histological grading is one of the most
i m p o rtant prognostic parameters.
NE breast carcinomas may be graded
using classical criteria described elsew
h e re .
Excluding the rare small cell variety,
45% of NE breast carcinomas are well
d i ff e rentiated, 40% are moderately diff
e rentiated, and only 15% are poorly diff
e rentiated. Small cell NE carc i n o m a s
should be considered as undiff e re n t i a t-
ed carcinomas {2535}.
Mucinous diff e rentiation is a favourable
p rognostic factor {2535}.
The prognosis of primary small cell carcinomas
of the breast depends on the
stage of disease at the time of diagnosis.
It has been demonstrated that low
stage small cell carcinomas respond to
conventional treatment without pro g re s-
sion of the disease at a follow up of 33
to 48 months {2662}.
Invasive papillary carcinoma
Definition
When papillary intraductal carc i n o m a s
invade, they generally assume the patt
e rn of infiltrating duct carcinoma and
lack a papillary arc h i t e c t u re. Most of the
published literature concerning papillary
c a rcinomas of the breast probably include
both invasive and in situ papillary
lesions as they do not generally specify
f e a t u res of an invasive process {413,
603,969,1269,1604,1618,1834}. In this
section, however, only data concern i n g
invasive papillary carcinomas will be
reviewed. Invasive papillary carc i n o m a s
comprise less than 1-2% of invasive
b reast cancers, and are characterized by
a relatively good prognosis {879,2567}.
ICD-O code 8503/3
Clinical features
Invasive papillary carcinomas are diagnosed
predominantly in postmenopausal
patients. Fisher et al. {879} noted a disproportionate
number of cases in non-
Caucasian women. Similar to medullary
carcinomas, Fisher et al. noted that a
significant pro p o rtion of patients with
invasive papillary carcinoma exhibit axill
a ry lymphadenopathy suggestive of
metastatic disease, but which on pathological
examination is due to benign
reactive changes {879}.
M a m m o g r a p h i c a l l y, invasive papillary
c a rcinoma is usually characterized by
nodular densities which may be multiple,
and are frequently lobulated {1880, 2567}.
These lesions are often hypoechoic on
ultrasound {1827}. One study noted the
d i fficulty in distinguishing between intracystic
papillary carcinoma, intracystic
p a p i l l a ry carcinoma with invasion, and
invasive papillary carcinoma {1827}.
A
B
Fig. 1.35 Invasive papillary carcinoma. A Microfocus magnification image of a papillary carcinoma shows a low density rounded tumour. B Large section histology.
C Ultrasonography shows a lobulated, well delineated lesion.
C
34 Tumours of the breast