Invasive breast carcinoma - IARC

Fig. 1.136 Fibromatosis. Fascicles of spindle myofibroblast invade the adipose tissue and extend between
lobules (on the left).
cells are absent. Variations include the
o c c u r rence of infiltrating margins, a
p rominent epithelioid cell component,
mono- or multinucleated giant cells with
a mild to severe degree of nuclear pleomorphism
and extensive myxoid or hyaline
change in the stroma. Occasionally,
lipomatous, smooth muscle, cart i l a g i-
nous or osseous components form additional
integral parts of the tumour {934,
1734-1736}. MFB should be distinguished
from nodular fasciitis, inflammatory
myofibroblastic tumour, fibromatosis,
benign peripheral nerve sheath tumours,
haemangiopericytomas and leiomyomas
{1736}. The differential diagnosis is
based on immunophenotype but even so
may be difficult in some cases.
Immunoprofile
The neoplastic cells react positively for
vimentin, desmin, α-smooth muscle actin
and variably for CD34, bcl-2 protein,
CD99 and sex steroid hormone receptors
(estrogen, progesterone and androgen
receptors) {1023,1733,1913}.
Fibromatosis
Definition
This uncommon, locally aggre s s i v e ,
lesion without metastatic potential originates
from fibroblasts and myofibroblasts
within the breast pare n c h y m a ,
excluding mammary involvement by
extension of a fibromatosis arising from
the pectoral fascia.
ICD-O code 8821/1
Synonym
Desmoid tumour.
Epidemiology
Fibromatosis accounts for less than 0.2%
of all breast lesions {390,681,1083,
2432,3063}. It is seen in women from 13
to 80 years (average 46 and median 40)
and is more common in the childbearing
age than in perimenopausal or postmenopausal
patients {681}. A few cases
have been reported in men {378,2482}.
Clinical features
The lesion presents as a solitary, painless,
firm or hard palpable mass. Bilateral
tumours are rare {681,2432,3063}. Skin or
nipple retraction may be observed {294}
and rarely nipple discharge {3063}.
M a m m o g r a p h i c a l l y, fibromatosis is indistinguishable
from a carcinoma {681}.
M a c r o s c o p y
The poorly demarcated tumour measure s
f rom 0.5 to 10 cm (average 2.5 cm)
{681,2432,3063} with a firm, white-gre y
cut surface.
Histopathology
M a m m a ry fibromatoses are histologically
similar to those arising from the fascia or
a p o n e u roses of muscles elsewhere in the
body with the same immunophenotype.
P roliferating spindled fibroblasts and
m y o f i b roblasts form sweeping and interlacing
fascicles; the periphery of the
lesion reveals characteristic infiltrating fing
e r-like projections entrapping mammary
ducts and lobules {3063}.
F i b romatosis must be distinguished fro m
several entities in the bre a s t .
F i b ro s a rcomas are richly cellular, with
nuclear atypia and a much higher mitotic
rate than fibromatosis. Spindle cell carc i-
nomas disclose more typical areas of carcinoma
and, in contrast to fibro m a t o s i s ,
the cells are immunoreactive for both
epithelial markers and vimentin {1022}.
Myoepithelial carcinomas are actin and/or
S-100 protein positive. While CAM 5.2
positivity may be weak, pancytokeratin
( K e rmix) is strongly expressed in at least
some tumour cells, and there is diff u s e
staining with CK34Beta E12 and CK 5,6.
Lipomatous myofibroblastomas show a
f i n g e r-like infiltrating growth pattern, re m i-
niscent of fibromatosis {1736}. However,
the cells are estrogen (ER), pro g e s t e ro n e
(PR) and androgen receptor (AR) positive
in 70% of cases, while fibromatosis does
not stain with these antibodies.
Nodular fasciitis is also composed of
i m m a t u re appearing fibroblasts but tends
to be more circumscribed, and has a
higher mitotic rate. The prominent inflamm
a t o ry infiltrate is scattered thro u g h o u t
the lesion and is not limited to the perip
h e ry as in fibro m a t o s i s .
Reactive spindle cell nodules and scars
a t the site of a prior trauma or surgery demonstrate
areas of fat necrosis, calcifications
and foreign body granulomas, feat
u res that are not common in fibromatosis.
I m m u n o p ro f i l e
The spindle cells are vimentin positive
and a small pro p o rtion of them are also
actin positive, while they are invariably
negative for cytokeratin and S-100 protein.
In contrast to one-third of extram
a m m a ry desmoid tumours {1662,1888,
2353}, fibromatoses in the breast are ER,
PR, AR, and pS2 (assessed as a measure
of functional ER) negative {681,2335}.
Prognosis and predictive factors
M a m m a ry fibromatoses display a low
p ropensity for local re c u r rence, with a
re p o rted frequency of 21% {1083}, 23%
{3063}, and 27% {2432} of cases comp
a red with that of 57% {790} for extram
a m m a ry lesions. When it does occur,
one or more generally develop within two
to three years of initial surgery {1083,
3063}, but local re c u r rence may develop
after a 6-year interval {3063}.
92 Tumours of the breast