Invasive breast carcinoma - IARC

Peritoneal tumours
S.C. Mok
J.O. Schorge
W.R. Welch
M.R. Hendrickson
R.L. Kempson
Definition
Rare neoplasms with primary manifestation
in the abdominal cavity in the
absence of a visceral site of origin. Both
malignant and benign tumours may
occur.
ICD-O code
Peritoneal mesothelioma 9050/3
Multicystic mesothelioma 9055/1
Adenomatoid tumour 9054/0
Desmoplastic small round
cell tumour 8806/3
Primary peritoneal carcinoma 8461/3
Primary peritoneal borderline
tumour 8463/1
Clinical features
Signs and symptoms
Patients with malignant peritoneal
tumours typically present with non-specific
manifestations including abdominal
discomfort and distension, digestive disturbances
and ascites. Less frequently, a
palpable mass or pelvic pain may be evident.
Benign peritoneal tumours are usually
asymptomatic.
Tumour spread and staging
Malignant peritoneal tumours spread primarily
by exfoliation of cancer cells from
the primary site of origin. Lymphatic and
haematogenous dissemination also commonly
occurs. However, some tumours
have been shown to arise from separate
intra-abdominal sites and are believed to
have a multifocal origin {2576 The staging
involves a combination of radiological
and operative findings, but these
tumours do not have individual staging
systems given their relative infrequency.
Most malignant tumours are confined to
the abdominal cavity at initial presentation.
Benign peritoneal tumours do not
metastasize and present as an isolated
lesion, often detected at the time of operation
for another indication.
Mesothelial tumours
Definition
Benign or malignant mesothelial tumours
that arise within the peritoneum.
Peritoneal malignant
mesothelioma
Definition
Malignant mesothelial tumours that arise
within the peritoneum. Epithelial
mesotheliomas may be divided into diffuse,
well diff e rentiated papillary and
deciduoid types. A less common variant
is the sarcomatous mesothelioma, which
includes the desmoplastic type.
Epidemiology
Age and sex distribution
Patients with diffuse mesotheliomas are
on average 50 years old {1443}, and
those with well differentiated papillary
tumours are 58 {383}.
Incidence and mortality
Primary neoplasms of the peritoneum are
rare compared to the wide variety of
benign and malignant peritoneal mûllerian
proliferations that women develop.
Two clinically benign to low grade proliferations,
multicystic mesothelioma and
well diff e rentiated papillary mesothelioma
are more common than diffuse
malignant mesothelioma, and the latter is
vastly less common than primary or secondary
extraovarian serous carcinoma.
Aetiology
Well diff e rentiated papillary, diff u s e
epithelial and deciduoid mesotheliomas
appear clinically related to asbestos
exposure in some cases {383,2633}.
Clinical features
The most common presenting features
are ascites and abdominal pain {1443}.
Macroscopy
The tumour typically consists of multiple
nodules measuring