Invasive breast carcinoma - IARC

Fig. 2.20 Mucinous endocervical-like borderline
tumour. The sectioned surface shows a solid and
cystic mucin-containing tumour arising in an
endometriotic cyst.
A
Fig. 2.21 Mucinous endocervical-like borderline tumour. A Note the papillae lined by atypical cells with
stratification and budding. B Some cells contain intracytoplasmic mucin, and the stroma of the papillae is
infiltrated by neutrophils.
B
Histopathology
They differ from intestinal-type bord e r l i n e
tumours in that the intracystic growth is
composed of broad bulbous papillae similar
to those of serous borderline tumours.
The epithelial cells lining the papillae are
columnar mucinous cells and ro u n d e d
cells with eosinophilic cytoplasm; the latter
a re often markedly stratified with detached
cell clusters. The nuclei are only slightly
atypical. Characteristically, there are many
acute inflammatory cells within the papillae
or free-floating in extracellular spaces.
Precursor lesions
Endocervical-like borderline tumours likely
arise from endometriosis {2497}. At
least in some cases the peritoneal implants
may arise from independent foci of
endometriosis with in situ transform a t i o n .
Prognosis and predictive features
Endocervical-like borderline tumours
may be associated with abdominal or
pelvic implants, some of which may
appear invasive, but the clinical behaviour
has been indolent in the relatively
few cases that have been re p o rt e d
{2497,2713}. However, more cases in this
category need to be studied.
Fig. 2.22 Mucinous cystadenoma. The presence of
pseudostratified epithelium with low cellular proliferation
in the absence of nuclear atypia does not
justify the borderline category.
Benign mucinous tumours
Definition
Benign mucinous tumours composed of
epithelium resembling endocervical or
g a s t rointestinal epithelium. The latter
almost always contains goblet cells, usually
contains neuoendocrine cells and
rarely contains Paneth cells.
Macroscopy
Mucinous cystadenomas are usually
large, unilateral, multilocular or unilocular
cystic masses containing watery or viscous
mucoid material. Cystadenofibromas
and adenofibromas are partially to
almost completely solid with only small
cysts {200}.
Histopathology
Benign mucinous tumours consist of cystadenomas,
cystadenofibromas and
a d e n o f i b romas These contain glands
and cysts lined by mucinous columnar
epithelium {2605}. Cellular stratification is
minimal, and nuclei are basally located
with only slight, if any, atypia. Cystadenomas
may have mucin extravasation
with or without a stromal reaction. An
ipsilateral dermoid cyst is present in 3-
5% of cases. The uncommon mucinous
a d e n o f i b roma is composed pre d o m i-
nantly of fibromatous stroma {200}.
Mucinous cystic tumours with
mural nodules
R a re mucinous cystic tumours contain
one or more solid mural nodules in which
the histological features differ markedly
f rom the background of either an intestinal-type
borderline tumour or carc i n o m a
{2007,2288,2290,2605}. The nodules are
y e l l o w, pink or red with areas of haemorrhage
or necrosis and range up to 12 cm
in size. They may be malignant (anaplastic
carcinoma, sarcoma or carc i n o s a rc o-
ma) or benign (sarcoma-like). Mucinous
cystic tumours containing more than 1 type
of mural nodule as well as mixed nodules
have been described. Anaplastic carc i n o-
matous nodules usually contain a pre d o m-
inant population of cytokeratin-positive,
large, rounded or spindle-shaped cells
with abundant eosinophilic cytoplasm
and high grade malignant nuclei. The few
s a rcomas that have been re p o rted have
been fibro s a rcomas or rhabdomyosarc o-
mas or have not been otherwise classified.
Sarcoma-like nodules are sharply circumscribed
and without vascular invasion
but otherwise may appear alarming, containing
pleomorphic cells with bizarre nuclei
and many mitotic figures, often accompanied
by spindle-shaped cells,
epulis-type giant cells, acute and chro n i c
i n f l a m m a t o ry cells and foci of haemorrhage
and necrosis. The sarcoma-like cells
may be weakly or focally cytokeratin-positive,
but this finding, in itself, does not i n d i-
cate a carcinomatous component {2605}.
The distinction is important because
patients with anaplastic carcinoma in a
mural nodule may follow a malignant
course {2290}, whereas the outcome of
Fig. 2.23 Mucinous adenofibroma. Uniform mucinous
glands are associated with a prominent
fibrous stroma.
Surface epithelial-stromal tumours 127