Invasive breast carcinoma - IARC

A
Fig. 1.145 Leiomyoma. A The well circumscribed margin (left) is apparent. B The bland smooth muscle cells proliferate in whorls and fascicles.
B
extraosseous osteosarcoma at other
sites of the body. Despite the pre d o m i-
nantly circumscribed margins, charact
e r i s t i c a l l y, at least focal infiltration is
p resent. The tumour is composed of a
spindle to oval cell population with variable
amounts of osteoid or osseous tissue;
cartilage is present in over a third
of the cases {2681} but no other diff e r-
entiated tissues.
The appearance of the tumours varies
depending on the cellular composition
( f i b roblastic, osteoblastic, osteoclastic)
as well as the type and amount of matrix
(osteoid, osseous, chondroid).
The osteoclastic giant cells are immun
o reactive with the macrophage marker
CD68 (clone KP1) while the spindle
cells fail to immunoreact with either
e s t rogen receptor (ER) or pro g e s t e ro n e
receptor (PR) or epithelial markers.
Prognosis and predictive factors
M a m m a ry osteosarcomas are highly
a g g ressive lesions with an overall fiveyear
survival of 38% {2681}. Rec
u r rences develop in over two-thirds of
the patients treated by local excision
and 11% of those treated by mastectom
y. Metastases to the lungs and
absence of axillary node involvement are
typical of osteosarcomas. Many of the
patients who develop metastases die of
the disease within 2 years of initial diagnosis
{2681}.
F i b roblastic osteosarcomas are associated
with a better survival compared to
the osteoblastic or osteoclastic variants.
Large tumour size at pre s e n t a t i o n ,
p rominent infiltrating margins and necrosis
are associated with more aggre s s i v e
b e h a v i o u r.
Leiomyoma and
leiomyosarcoma
D e f i n i t i o n
Benign and malignant tumours composed
of intersecting bundles of smooth
muscle which is mature in benign lesions.
Malignant lesions are larger in size and
show more mitotic activity in the neoplastic
cells.
ICD-O codes
L e i o m y o m a 8890 / 0
L e i o m y o s a rc o m a 8890 / 3
E p i d e m i o l o g y
Benign and malignant smooth muscle
tumours of the breast are uncommon and
re p resent less than 1% of breast neoplasms.
The majority of leiomyomas originate
from the are o l a r-nipple complex and
a minority occur within the breast pro p e r
{1981}. Leiomyosarcomas arise mainly
within the breast {821}.
The age at presentation of leiomyomas
and leiomyosarcomas overlaps, extending
from the fourth to the seventh
decades. However, cases of both have
been re p o rted in adolescents {2000} and
patients over eighty years old {821}.
Clinical features
Both leiomyomas and leiomyosarc o m a s
usually present as a slowly growing palpable
mobile mass that may be painful.
Incidental asymptomatic leiomyomas disc
o v e red in mastectomy specimens have
been re p o rted {1981}.
M a c r o s c o p y
These lesions appear as well circ u m-
scribed firm nodules with a whorled or
lobulated cut surface. Their size ranges
f rom 0.5 to 15 cm {770,2000}.
H i s t o p a t h o l o g y
The histopathology and immunophenotype
are identical to that seen in smooth
muscle tumours elsewhere in the body.
These neoplasms may be well circ u m-
scribed {1981} or show irregular infiltrative
borders {2000}. Both are composed
of spindle cells arranged in interlacing
fascicles.
In leiomyomas, these cells have elongated
cigar-shaped nuclei and eosinophilic
cytoplasm without evidence of atypia.
Mitoses are sparse and typically fewer
than 3 per 10 high power fields {458}. In
l e i o m y o s a rcomas, nuclear atypia and
mitotic activity are more prominent {821}.
Tumour necrosis may also be observed.
Infiltrating margins may not be evident in
some leiomyosarc o m a s .
D i ff e rential diagnosis
A diagnosis of a smooth muscle tumour of
the breast should be considered only after
excluding other breast lesions that may
show benign or malignant smooth muscle
d i ff e rentiation i.e. fibroadenoma, muscular
h a m a rtoma and sclerosing adenosis
should be distinguished from leiomyoma;
spindle cell myoepithelioma and sarc o-
matoid carcinoma from leiomyosarc o m a .
Prognosis and predictive factors
Leiomyomas are best treated by complete
excision whereas, wide excision
with tumour- f ree margins is re c o m m e n d-
ed for leiomyosarcomas. Late local re c u r-
rence and metastatasis have been re p o r-
ted in cases of mammary leiomyosarc o-
ma {458,2014}.
98 Tumours of the breast