Invasive breast carcinoma - IARC

areas are limited to less than 30% of the
tumour. When the smooth muscle component
comprises 30% or more of the
tumour, the lesion is designated as a
mixed endometrial stromal and smooth
muscle tumour. Focal rhabdoid differentiation
has been described in one case
{1813}.
The differential diagnosis includes stromal
nodule, intravenous leiomyomatosis,
adenomyosis with sparse glands and
adenosarcoma. In a biopsy or curettage
specimen it is often impossible to distinguish
low grade ESS from a stromal nodule,
a non-neoplastic stromal proliferation
or a highly cellular leiomyoma.
Histogenesis
Extrauterine primary endometrioid stromal
sarcomas occur and often arise from
endometriosis {280}.
Prognosis and predictive factors
Low grade ESS is characterized by indolent
growth and late recurrences; up to
one-half of patients develop one or more
pelvic or abdominal recurrences. The
median interval to re c u r rence is 3-5
years but may exceed 20 years.
Pulmonary metastases occur in 10% of
stage I tumours {1311}.
The 5-year survival rate for low grade
ESS ranges from 67% {2048} to nearly
100% with late metastases and a relatively
long-term survival despite tumour
dissemination {437,811,2263}. The surgical
stage is the best predictor of recurrence
and survival for ESSs {300,437}.
Both recurrent and metastatic ESSs may
remain localized for long periods and are
amenable to successful treatment by
resection, radiation therapy, pro g e s t i n
therapy or a combination there o f
{300,1750,3089}.
Conservative management has been
advocated for some patients with low
grade ESS {1677}. In some studies that
have utilized progestin therapy, 100%
survival rates have been achieved even
for patients with stage III tumours {2263}.
Endometrial stromal nodule
Definition
A benign endometrial stromal tumour
characterized by a well delineated,
expansive margin and composed of neoplastic
cells that resemble proliferative
phase endometrial stromal cells supported
by a large number of small, thinwalled
arteriolar-type vessels.
Clinical features
Women with a stromal nodule range in
age from 23-75 years with a median of 47
years {292,437,2098,2101,2102,2883}.
About one-third of the women are postmenopausal.
Tw o - t h i rds of the women
p resent with abnormal uterine bleeding
and menorrhagia. Pelvic and abdominal
pain occur less fre q u e n t l y.
Macroscopy
The tumour is characteristically a solitary,
well delineated, round or oval, fleshy nodule
with a yellow to tan sectioned surf a c e .
The median tumour diameter is 4.0 cm
(range 0.8-15 cm) {2883}. About two-third s
a re purely intramural without any appare n t
connections to the endometrium, 18% of
the lesions are polypoid, and others involve
both the endometrium and myometrium.
Histopathology
The histological appearance is identical to
that described above for low grade ESS
except for the absence of infiltrative margins
{292,437,2097,2098,2101,2102,2883}.
R a re, focal marginal irregularity in the form
of finger-like projections that do not exceed
3 mm is acceptable. Smooth and skeletal
muscle along with sex cord diff e re n t i a t i o n
may be present focally {1685}.
The differential diagnosis includes low
grade ESS and highly cellular leiomyoma.
The presence of at least focal typical
neoplastic smooth muscle bundles,
large, thick walled vessels and strong
i m m u n o reactivity with desmin and h-
caldesmon and the absence of reactivity
with CD10 help distinguish a highly cellular
leiomyoma from a stromal nodule.
A
B
Fig. 4.27 Low grade endometrial stromal sarcoma
(ESS). Myoinvasive low grade ESS that shows
endometrial glandular differentiation. The
myometrium is seen above.
C
Fig. 4.28 Endometrial stromal nodule. A Note the circumscribed, bulging, yellow nodule in the myometrium.
B Cytologically bland ovoid cells without discernible cytoplasm proliferate in a plexiform pattern and are
supported by small arterioles. C The circumscribed myometrial nodule is composed of closely packed cells.
D The tumour cells are strongly immunoreactive for CD10.
D
Mesenchymal tumours and related lesions 235