Invasive breast carcinoma - IARC

Fig. 2.96 Embryoid body in polyembryoma. Note the
blastocyst-like formation consisting of an embryonic
disc that is continuous with a primitive yolk
sac cavity exhibiting alpha-fetoproten secretion in
its distal portion.
Clinical features
Clinically, hormonal manifestations such
as precocious pseudopuberty and vaginal
bleeding are present in children and
young adults.
Macroscopy
Macroscopically, tumours are large and
haemorrhagic, and large luteinized nodules
or cysts due to β-hCG stimulation
may appear in the uninvolved ovarian tissue.
Histopathology
Morphologically identical to gestational
choriocarcinoma, primary non-gestational
choriocarcinoma is rare in pure form,
differentiates as an admixture of cytotrophoblast,
syncytiotrophoblast and
extravillous trophoblast and is usually
found associated with other germ cell
components {2704}. Histologically, there
are fenestrated or plexiform sheets or
pseudopapillae of cytotrophoblast and
extravillous trophoblast admixed with
numerous syncytiotrophoblasts. Tumour
can be found in blood-filled spaces and
sinusoids. Vascular invasion is frequent.
The immunophenotype is characteristic
for each type of proliferating trophoblastic
cell {1759} and includes cytokeratins,
human placental lactogen and, above
all, β-hCG.
Differential diagnosis
When found in a pure form in childbearing
age, gestational choriocarc i n o m a ,
either primary in the ovary {3024} or
metastatic {718} must be excluded. This
may be accomplished by identifying
p a t e rnal sequences by DNA analysis
{1698,2655}.
Prognosis and predictive factors
The distinction from gestational choriocarcinoma
is important since non-gestational
choriocarcinoma has a less
favourable prognosis and requires more
aggressive chemotherapeutic treatment
regimens.
Mixed germ cell tumours
Definition
Mixed germ cell tumours are composed
of at least two different germ cell elements
of which at least one is primitive.
Clinical features
The value of tumour markers such as β-
hCG and AFP in the diagnosis and follow-up
of patients with mixed germ cell
tumours containing elements of choriocarcinoma
or yolk sac tumour has been
proven over the years {2850}. Elevated
serum levels of these markers should
prompt a search for different components
with extensive sampling of the
tumour.
Histopathology
Histologically, the most common combination
of neoplastic germ cell elements
found in ovarian mixed germ cell
tumours is dysgerminoma and yolk sac
tumour {2850}. Additional neoplastic
germ cell elements, including immature
or mature teratoma, embryonal carcinoma,
polyembryoma and/or choriocarcinoma,
may also be present. All components
of a mixed germ cell tumour and
their approximate proportions should be
mentioned in the diagnosis.
Most ovarian embryonal carcinomas are
really malignant mixed germ cell
tumours, usually admixed with yolk sac
tumour and showing a large or predominant
component of embryonal carcinoma
{2850}. Although polyembryoma may
have been the predominant malignant
germ cell element within the tumour, a
careful review of all the published cases
of ovarian polyembryoma shows that
other germ cell elements were also present
{2850}. Also, ovarian choriocarcinoma
of germ cell origin is in the majority of
cases combined with other neoplastic
germ cell elements. Immunohistochemical
demonstration of β-hCG and AFP is a
useful diagnostic modality in this group
of tumours, as is the demonstration of
PLAP in a component of dysgerminoma
Prognosis and predictive factors
All elements in a malignant mixed germ
cell tumour are capable of widespread
metastatic dissemination. The metastases
may be composed of a single neoplastic
germ cell element or of various
elements.
Although these tumours are highly
responsive to platinum-based chemotherapy,
the therapeutic regimens should
be based primarily on the most malignant
elements of the tumour {2850}.
Biphasic or triphasic teratomas
Fig. 2.97 Ovarian choriocarcinoma. A plexiform pattern is present with syncytiotrophoblasts covering clusters
of smaller cytotrophoblasts.
Definition
Tumours composed of derivatives of two
or three primary germ layers (ectoderm,
mesoderm, endoderm).
168 Tumours of the ovary and peritoneum