Invasive breast carcinoma - IARC

A
Fig. 2.24 Mucinous borderline tumour (MBT). A Note the microinvasive focus in a MBT. B Mural nodule from another MBT. The mural nodule is composed of epithelial
cells with anaplastic nuclei, abundant cytoplasm and some intracytoplasmic mucin in a fibrous stroma.
B
those with only sarcoma-like nodules is
the same as the corresponding category
of mucinous tumour without the nodules
{163}. Although the foci of anaplastic carcinoma
are found more often in advanced
stage tumours, it is now apparent that
when they are confined to intact stage IA
tumours, they are not necessarily associated
with an adverse outcome {2401}.
Mucinous cystic tumours
associated with pseudomyxoma
peritonei
Since there is strong evidence that ovarian
mucinous tumours associated with
pseudomyxoma peritonei (PP) are almost
all metastatic rather than primary, it is
important that such tumours are not diagnosed
as stage II or III mucinous borderline
tumours or carcinomas without first
excluding an appendiceal or other gast
rointestinal primary. Present evidence
suggests that almost all genuine ovarian
mucinous borderline tumours are stage
1. The number of stage 2 and 3 tumours
in this category has been greatly exaggerated
by including cases in which PP
is associated with an undetected primary
tumour in the appendix. Also, there is
p robably an unwarranted appare n t
increase in the number of high stage
ovarian mucinous carcinomas because
of undetected primary intestinal mucinous
carcinomas associated with the
clinical syndrome of PP.
Pseudomyxoma peritonei is a clinical
term used to describe the finding of
abundant mucoid or gelatinous material
in the pelvis and abdominal cavity surrounded
by fibrous tissue. The mucus
may be acellular or may contain mucinous
epithelial cells. Mucinous ascites,
the presence of free-floating mucinous
fluid, in the peritoneal cavity, almost
never leads to pseudomyxoma peritonei.
A reas of pseudomyxoma peritonei
should be thoroughly sampled and
examined histologically. The degree of
atypia (benign, borderline or malignant)
of any epithelial cells that are present
should be reported, as well as whether
the mucin dissects into tissues with a
fibrous response or is merely on the surface.
Pseudomyxoma peritonei with
epithelial cells that are benign or borderline-appearing
has been termed "disseminated
peritoneal adenomucinosis"
by some authors {2409}, and patients
with this finding have had a benign or
p rotracted clinical course. In cases
w h e re the epithelial cells of the
pseudomyxoma peritonei appear malignant,
termed "peritoneal mucinous carcinomatosis"
{2409}, the source has usually
been the appendix or colon, and the
clinical course has usually been fatal.
Pseudomyxoma peritonei may be present
in women without a cystic ovarian
tumour or in men. In such cases the
source is almost always a gastrointestinal
mucinous neoplasm, most commonly
f rom the appendix {2409}. In cases
where there is an appendiceal tumour
and a mucinous cystic ovarian tumour,
Fig. 2.25 Mucinous cystic tumour associated with
pseudomyxoma peritonei. The sectioned surface
shows a multiloculated cystic tumour associated
with areas of haemorrhage.
Fig. 2.26 Pseudomyxoma peritonei involving the
omentum. Strips of low grade neoplastic mucinous
epithelium are associated with abundant extracellular
mucin.
Fig. 2.27 Mucinous appendiceal tumour associated
with pseudomyxoma peritonei. Note on the left, the
dilatation of the wall and distention of the mucosa
by mucin-producing tumour cells.
128 Tumours of the ovary and peritoneum