Invasive breast carcinoma - IARC

Fig. 1.112 Microglandular adenosis. An extensive
lesion that presented as a palpable mass; the characteristic
open lumens of the tubules and the colloid-like
secretory material are apparent, providing
clues to the nature of the process.
Fig. 1.113 Microglandular adenosis with diffusely
arranged small uniform glands, separated by a
densely collagenous background.
Fig. 1.114 Microglandular adenosis. The tubules
are lined by a single layer of attenuated to cuboidal
epithelial cells with vacuolated cytoplasm; colloidlike
secretory material is present within the lumen.
Fig. 1.115 Microglandular adenosis. Immunostain
for smooth muscle actin confirms absence of a
myoepithelial cell layer in MGA; the adjacent
TDLUs show actin-positive myoepithelial cells.
Fig. 1.116 Microglandular adenosis with atypia.
There is diminished intraluminal colloid-like secretion,
enlarged cells displaying mild to moderate
nuclear pleomorphism and mitotic figures.
Fig. 1.117 Ductal carcinoma in situ arising in
microglandular adenosis. Note the significant
atypia of the cells proliferating within the obliterated
tubules.
plex sclerosing lesion (CSL) to larger ones
that contain a variety of ductal epithelial
hyperplasia along with sclerosis.
Synonyms
Radial scar, sclerosing papillary lesion,
radial sclerosing lesion, scleroelastotic
s c a r, stellate scar, benign sclero s i n g
ductal proliferation, non-encapsulated
sclerosing lesion, infiltrating epitheliosis.
Epidemiology
The reported incidence varies depending
on the mode of detection and how
detected by mammography when the
appearance mimics that of an infiltrating
carcinoma producing an irregular stellate
density. Very occasionally they are of sufficient
size to produce a palpable mass
{2725}. They are often multiple and frequently
bilateral.
Macroscopy
These lesions may be undetected on
gross examination or may be of sufficient
size to produce an irregular area of firmness
which can exhibit yellow streaks
reflecting the elastotic stroma. The
appearance may be indistinguishable
from that of a carcinoma.
Histopathology
RSs are composed of a mixture of benign
changes of which adenosis forms a
major part. They have a stellate outline
with central dense hyalinized collagen
and sometimes marked elastosis.
Entrapped in the scar are small irregular
tubules. The two cell layer is usually
retained although this may not always be
visible on haematoxylin and eosin staining
and the myoepithelial layer is occasionally
inapparent. The tubules sometimes
contain eosinophilic secre t i o n s .
Around the periphery of the lesion there
are various degrees of ductal dilatation,
ductal epithelial hyperplasia, apocrine
metaplasia and hyperplasia. In the more
complex larger CSLs, several of these
lesions appear to combine and then converge
with prominent areas of sclerosing
adenosis, and small, frequently sclerosing,
peripheral papillomas and various
patterns of intraepithelial proliferation.
Differential diagnosis
Distinction from carcinoma depends on
the characteristic architecture of a CSL,
the lack of cytological atypia, the presence
of a myoepithelial layer (in most
cases) and basement membrane around
the tubular structures (demonstration by
i m m u n o h i s t o c h e m i s t ry may be necessary),
the presence of a dense hyalinized
stroma and lack of a reactive fibroblastic
stroma.
Fig. 1.118 Radial scar. Centre of a radial scar with
two tubular structures, surrounded by hyalinized
and elastotic tissue. Note the atrophic myoepithelial
layer.
Benign epithelial proliferations
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