Invasive breast carcinoma - IARC

endometrioid adenocarcinoma fro m
atypical complex hyperplasia is best provided
by stromal disappearance
between adjacent glands, i.e. confluent,
c r i b r i f o rm or villoglandular pattern s
{1433,1689,2688,2691}. Other feature s
that may be helpful include a stromal
desmoplastic response and/or tumour
n e c rosis. Stromal foam cells may be
associated with adenocarcinoma or its
precursors.
Variants of endometrioid
adenocarcinoma
Endometrial proliferations may exhibit a
variety of differentiated epithelial types
including squamous/morules, mucinous,
ciliated, cleared or eosinophilic cells,
and architectural variations including
papillary formations. These cell types are
often called metaplasias and may be
e n c o u n t e red in benign, pre m a l i g n a n t
and malignant epithelia. When prominent
in a carcinoma the neoplasm is termed a
"special variant" carcinoma.
Variant with squamous differentiation
From 20-50% or more of endometrioid
a d e n o c a rcinomas contain vary i n g
amounts of neoplastic epithelium showing
squamous differentiation. Although
the distinction between endometrioid
adenocarcinoma with and without squamous
diff e rentiation is not clinically
important, the recognition of squamous
differentiation is nevertheless essential
because the squamous or morular elements
should not be considered a part of
the solid component that increases the
grade of an endometrioid carcinoma.
The criteria for squamous differentiation
{2691} are as follows:
(1) Keratinization demonstrated with
standard staining techniques.
(2) Intercellular bridges and/or
(3) Three or more of the following four criteria:
(a) Sheet-like growth without gland formation
or palisading.
(b) Sharp cell margins.
(c) Eosinophilic and thick or glassy cytoplasm.
(d) A decreased nuclear to cytoplasmic
ratio as compared with foci elsewhere in
the same tumour.
Fig. 4.03 Endometrioid adenocarcinoma. The bizarre nuclear atypia raises the tumour grade but should also
prompt consideration of a serous adenocarcinoma.
Fig. 4.04 Well differentiated endometrioid adenocarcinoma, ciliated cell variant. Cilia lining the neoplastic
glands are prominent.
Villoglandular variant
This type is the next most commonly
encountered endometrioid adenocarcinoma
variant and is usually seen involving
part of a low grade endometrioid carcinoma
but not the entire tumour. In this
pattern numerous villous fronds are seen,
but their central cores are delicate, and
cells with the usual cytological features
(including stratification perpendicular to
the basement membrane) line the villi.
These features are in contrast to the
more complex papillary architecture and
high grade nuclear features that are typical
of serous and clear cell adenocarcinomas
growing in a papillary pattern.
Secretory variant
Occasional endometrioid adenocarcinomas
are composed of glands lined by
epithelium with voluminous, usually subnuclear,
glycogen vacuoles reminiscent
of early secretory endometrium. These
tumours have minimal nuclear atypia and
are diagnosable as carcinoma only by
virtue of a confluent, cribriform or villoglandular
pattern. As with the other variants,
this pattern may be seen as the
only one in an endometrioid adenocarci-
Epithelial tumours and related lesions 223