Invasive breast carcinoma - IARC

p redominantly of apocrine cells constitute
at the most 4% of all invasive carc i-
nomas; focal apocrine cells diagnosed
either by histology, immunohistochem
i s t ry or genetic techniques are frequent
and occur in at least 30% of "ord i-
n a ry" invasive carcinomas {1700}.
Clinical features
T h e re is no diff e rence between the clinical
or mammographic features, size
and site of carcinomas among apocrine
and non-apocrine lesions. Bilaterality is
r a re in apocrine carc i n o m a s .
Fig. 1.37 Invasive micropapillary carcinoma. Tumour cell clusters with irregular central spaces proliferate
within empty stromal spaces. Some clusters have reversed polarity with an “inside out” morphology.
lymph node metastases and malignant
cells in pleural fluids all show the same
arrangement found in the primary
tumour.
Prognostic and predictive features
This unusual growth pattern is corre l a t-
ed with the presence of vascular invasion
and axillary lymph node metastases.
In multivariate analyses, however,
a micro p a p i l l a ry growth pattern has no
independent significance for survival
{ 1 9 8 2 , 2 1 9 4 } .
Apocrine carcinoma
Definition
A carcinoma showing cytological and
immunohistochemical features of apocrine
cells in >90% of the tumour cells.
ICD-O code 8401/3
Epidemiology
The re p o rted incidence of apocrine carcinoma
depends on the method of
detection. Based on light micro s c o p y
alone it is only 0.3-4% {149,910}. An
ultrastructural study found a fre q u e n c y
of 0.4% for apocrine carcinomas in a
p rospective series {1926}.
Immunohistochemical studies using
anti GCDFP-15, a putative marker of
apocrine diff e rentiation {1800} gave
conflicting data with an incidence ranging
from 12% {809} to 72% {3113}.
Twenty seven per cent of cases were
positive with an in situ hybridization
method using a mRNA probe against
the sequence of the GCDFP-15 {1700}.
In conclusion, carcinomas composed
Histopathology
Any type and grade of breast carc i n o m a
can display apocrine diff e re n t i a t i o n
including ord i n a ry invasive duct carc i-
nomas, tubular, medullary, papillary,
m i c ro p a p i l l a ry and neuro e n d o c r i n e
types {17,569,809,1700}, as well as
classical and pleomorphic invasive lobular
carcinomas {802,808}. However,
recognition of apocrine carcinoma at
p resent has no practical import a n c e
and is only of academic value.
Apocrine lobular in situ neoplasias
{802,2534}, and apocrine ductal in situ
c a rcinomas (ADCIS) are also well re c-
ognized {17,1605,2887}. Apocrine carcinomas,
whatever their origin, are usually
composed by two types of cells variously
intermingled {804}. Type A cell
recognized first by most authors has
abundant granular intensely
eosinophilic cytoplasm. The granules
a re periodic acid-Schiff positive after
diastase digestion. Their nuclei vary
f rom globoid with prominent nucleoli to
h y p e rc h romatic. Some tumours, when
constituted by a pure proliferation of
type A cells, superficially mimic granular
cell tumours. This type of apocrine
c a rcinoma has sometimes been re f e r re d
A
B
Fig. 1.38 Invasive micropapillary carcinoma. A Note the prominent vascular invasion and occasional pyknotic nuclei within the central spaces. B Lymph node metastasis.
C EMAstaining of of the peripheral cell membranes suggestive of an ‘inside out’ morphology.
C
36 Tumours of the breast