Invasive breast carcinoma - IARC

cells contain intracytoplasmic lumens
c o n f i rming a glandular cell population.
Adenosquamous carcinoma
Definition
An invasive carcinoma with areas of well
developed tubule/gland formation intimately
admixed with often widely dispersed
solid nests of squamous diff e-
re n t i a t i o n .
ICD-O code 8560/3
Histopathology
While focal squamous diff e re n t i a t i o n
has been observed in 3.7% of infiltrating
duct carcinomas {878}, a pro m i-
nent admixture of invasive ductal and
squamous cell carcinoma is rarely observed.
The squamous component is
often keratinizing, but ranges from very
well diff e rentiated keratinizing areas to
poorly diff e rentiated non-keratinizing
foci.
Eight tumours described as examples of
low grade m u c o e p i d e rmoid carc i n o m a,
comparable to those occuring in the
s a l i v a ry glands, have been re p o rted
in the breast; these behave as low
grade carcinomas {1130,1156,1515,
1 6 2 9 , 1 7 0 9 , 2 1 9 1 , 2 2 3 4 } .
Fig. 1.46 Adenosquamous carcinoma. Both glandular and squamous differentiation coexist in this carcinoma.
Immunoprofile
The squamous component is negative
for both ER and PR, while the positivity
of the ductal carcinoma component
for ER and PR depends on its degree of
d i ff e re n t i a t i o n .
Low grade adenosquamous
carcinoma
Low grade adenosquamous carc i n o m a
{2431} is a variant of metaplastic carc i-
noma which is morphologically similar to
adenosquamous carcinoma of the skin
and has been classified by some as
syringomatous squamous tumour {2816}.
The same lesion has been interpreted as
an infiltrating syringomatous adenoma
by others who prefer to avoid designation
of carcinoma for a group of lesions
which mainly recur after local excision.
ICD-O code 8560/1
Synonym
Infiltrating syringomatous adenoma. This
entity is also discussed in Tumours of
the Nipple.
Fig. 1.47 Low grade adenosquamous carcinoma / infiltrating syringomatous adenoma. A highly infiltrative
growth pattern is responsible for the high frequency of local recurrence associated with many lesions.
Clinical features
The age range at presentation is wide.
These lesions usually present as a small
palpable mass between 5 and 80 mm in
size.
Histology
These tumours are composed of small
glandular structure and solid cords of
epithelial cells haphazardly arranged in
an infiltrative spindle celled stromal component
{2421,2995}. The proportions of
these three components is variable
between cases. The solid nests of cells
may contain squamous cells, squamous
pearls or squamous cyst formation. The
s t roma is typically "fibro m a t o s i s - l i k e "
being cellular and composed of bland
spindle cells. The stromal component
can, however, be collagenous, hyalinized
or variably cellular, and osteocartilagenous
foci can occur rarely. It has been
recognized that some low grade
adenosquamous carcinomas may be
found in association with a central sclerosing
proliferation such as a radial scar,
sclerosing papillary lesion or sclerosing
adenosis {672,2421,2995}. The frequen-
Invasive breast cancer
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