Invasive breast carcinoma - IARC

A
Apocrine adenoma
ICD-O code 8401/0
Synonym
Nodular adenosis with apocrine metaplasia.
Sometimes the epithelial cells of nodular
adenosis show extensive apocrine metaplasia;
these lesions may be term e d
apocrine adenoma {561,1713,2442}.
Immunoprofile
The immunophenotype of adenomas is
similar to normal breast and reflects the
various metaplastic and or secre t o ry
changes affecting them.
Differential diagnosis
D i ff e rentiation of adenomas fro m
fibroadenomas is based on the prominent
proliferating stromal component and
the often elongated and compre s s e d
epithelial elements in the intracanalicular
variant of the latter.
B
Fig. 1.122 Lactating adenoma. Epithelial cells show extensive secretory changes (A, B). Fig. 1.123 Pleomorphic adenoma. Nests of clear
myoepithelial cells proliferate around few, barely
s a l i v a ry glands Some authors {2442,
2730,2753} consider pleomorphic adenoma
to be a form of intraductal papilloma
with extensive cartilaginous metaplasia.
Because of the presence of a
c h o n d roid stromal component, pleomorphic
adenomas pose a difficult diff e re n-
tial diagnosis from metaplastic carc i n o-
mas with a mesenchymal component
and primary sarcomas of the bre a s t .
The presence of foci of intraductal or
invasive carcinoma points to the diagnosis
of metaplastic carcinoma, while
extensive cellular anaplasia characterizes
sarc o m a s .
Ductal adenoma
Definition
A well circumscribed benign glandular
proliferation located, at least in part, within
a duct lumen {151}.
ICD-O code 8503/0
apparent darker epithelial cells; abundant cartilage
is present on the right.
Pleomorphic adenoma
Definition
A rare lesion morphologically similar to
pleomorphic adenoma (benign mixed
tumour) of the salivary glands.
ICD-O code 8940/0
Epidemiology
These lesions have been re p o rted in
patients (mainly females) over a wide
range of age {172,454}. Multiple tumours
have been described {454,2874}. Calcification
is common and gives a diagnostically
important sign on mammography.
Histopathology
The histological picture is the same as
that seen in pleomorphic adenomas of
Synonym
Sclerosing papilloma.
E p i d e m i o l o g y
These lesions occur over a wide age
range but are most frequent in women
over 40 years {151,1577}. It is debatable
whether these lesions re p resent the
s c l e rotic evolution of an intraductal
papilloma or are a distinct entity.
Clinical features
They may present as a mass or rarely as
a nipple discharge. Imaging shows a
density which can mimic a carc i n o m a .
Histopathology
Arranged mainly at the periphery are
glandular structures with typical dual
cell layer while in the centre there is
dense scar-like fibrosis. The compact
Fig. 1.124 Ductal adenoma, characterized by a
“polypoid “ protrusion into a distended duct; a few
papillary projections are evident (arrow).
p roliferating tubules, compressed or
slightly dilated, and surrounded by
f i b rosis may impart a pseudoinfiltrative
appearance. Epithelial and stro m a l
changes similar to those observed in
intraductal papillomas can occur; apocrine
metaplasia is frequent. {1577}.
P a p i l l a ry fronds are not always
detectable in a given plane of section.
Prognosis and predictive factors of
mammary adenomas
All adenomas of the breast are benign
lesions that do not recur if adequately
excised and do not predispose to carc
i n o m a .
Benign epithelial proliferations
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