Invasive breast carcinoma - IARC

A
Fig. 2.142 Leiomyomatosis peritonealis disseminata. A There are numerous small nodules dispersed throughout the omental surfaces. B One of multiple nodules
composed of uniform smooth muscle cells in the peritoneum is illustrated.
B
rarely, if ever, do they recur after adequate
excision {506}.
Smooth muscle tumour
Leiomyomatosis peritonealis
disseminata
Definition
A benign entity in which numerous small
nodules composed of smooth muscle
are present in the peritoneal cavity.
Synonym
Diffuse peritoneal leiomyomatosis.
Epidemiology
This condition is rare and occurs in
women predominantly in their late reproductive
years.
Clinical findings
With few exceptions the patients are
asymptomatic. The tumours are found
incidentally at the time of laparotomy for a
leiomyomatous uterus or during caesarean
section. At the time of operation the
surgeon is likely to be alarmed since this
entity may be macroscopically indistinguishable
from diffuse carcinomatosis of
the peritoneum. Intraoperative consultation
is re q u i red to establish the diagnosis.
Macroscopy
The tumour typically consists of numerous
small, grey-white nodules.
Histopathology
The tumours consist of multiple nodules
of well diff e rentiated smooth muscle
arranged in an intersecting pattern .
Cases may occur in conjunction with
endometriosis or muticystic mesothelioma,
and a single case was associated
with both conditions {3268}.
Prognosis and predictive factors
The tumours may regress spontaneously,
and conservative management is appropriate.
Tumour of uncertain origin
Desmoplastic small
round cell tumour
Definition
A malignant peritoneal tumour of uncertain
origin that shows divergent differentiation
and is typically composed of nodules
of small cells surrounded by a
prominent desmoplastic stroma.
ICD-O code 8806/3
Epidemiology
Desmoplastic small cell tumour (DSRCT)
is an extremely rare malignancy that has
a strong male predilection and occurs
most commonly in adolescents and
young adults (mean age 19 years) {984}.
Histopathology
H i s t o l o g i c a l l y, DSRCT consists of sharply
c i rcumscribed aggregates of small
epithelioid cells separated by fibrous stroma.
The tumour cells typically are uniform
with scanty cytoplasm, have indistinct cell
b o rders, and small to medium-sized,
round, oval or spindle-shaped hyperc h romatic
nuclei. Mitotic figures are numero u s .
I m m u n o h i s t o c h e m i s t ry indicates simultaneous
divergent expression within the
tumour including reactivity for epithelial
(keratin, epithelial membrane antigen),
neural (neuron-specific enolase) and
muscle/mesenchymal (desmin) markers
{ 9 8 4 } .
Histogenesis
These tumours are malignant neoplasms
of uncertain histogenesis. Their location
primarily in the peritoneum suggests a
possible histogenetic relationship with
mesothelium. The distinctive immunophenotype
suggests multilineage {984,1038}.
Somatic genetics
DSRCT has a characteristic re c i p ro c a l
c h romosome translocation t(11;22)(p13;
q12) which results in the fusion of the
Ewing tumour (E W S) gene and the Wilms
tumour (W T 1) gene {900,903}. The re s u l t-
ant chimeric E W S - W T 1 transcript produces
a tumour-specific fusion protein that
t u rns the W T 1 tumour suppressor gene
into a dominant oncogene {2340}. As a
result, cytogenetic analysis can be helpful
in excluding the diagnosis of other ro u n d
cell tumours.
Genetic susceptibility
No familial clustering has been described.
Prognosis and predictive factors
Clinical criteria
Multimodality therapy with induction
c h e m o t h e r a p y, aggressive surgical
debulking and external beam radiotherapy
is advocated for the initial treatment of
DSRCT. However, the prognosis is over-
200 Tumours of the ovary and peritoneum