Invasive breast carcinoma - IARC

Pseudoangiomatous stromal
hyperplasia
Definition
A benign lesion consisting of complex
anastomosing slit-like pseudovascular
spaces, that are either acellular or lined
by slender spindle-shaped stromal cells.
Fig. 1.133 Pseudoangiomatous stromal hyperplasia (PASH). Interanastomosing, empty, slit-like spaces
within breast stroma are typical.
Pathology
M a c roscopic and histopathological
appearances are similar to angiomatosis
at other sites. The haemorrhagic spongy
lesions are composed of usually thin
walled large blood or lymphatic vessels
d i ffusely extending throughout the
parenchyma of the breast.
Prognosis and predictive factors
R e c u r rence after incomplete excision
has been reported, and may occur after
a long disease-free interval {2416}. In
many cases, complete excision requires
a mastectomy.
Haemangiopericytoma
Definition
A circumscribed area of bland ovoid to
spindled cells proliferating aro u n d
branching and “stag-horn” vessels.
ICD-O codes
Benign 9150/0
NOS 9150/1
Malignant 9150/3
Epidemiology
This is a rare mesenchymal tumour.
A round 20 primary haemangiopericytomas
have been reported in the breast.
The patients are mostly women aged
22–67, but a few cases have been
reported in children (5 and 7 years old)
and in men {118,2889}.
Clinical features
Patients usually present with a mass that
appears as a well circumscribed area of
density on mammography.
Macroscopy
The tumours are round to oval, well circumscribed
and range in size from 1 to
19 cm {118,1415,2855,2889}. They are
firm with a solid, yellow-tan to grey-white
cut surface. Myxoid areas alternate with
small cysts filled with watery fluid.
Haemorrhage and necrosis are evident
in some larger tumours.
Histopathology
The histological and immunophenotype
appearances are similar to haemangiopericytomas
described elsewhere {2889}.
They are composed of a compact pro l i f e-
ration of plump ovoid to spindle cells with
indistinct cell margins arranged aro u n d
an abundance of usually thin-walled,
i r regularly branching vascular channels.
Some of the branching vessels assume
a “stag-horn” configuration. Mammary
ducts and ductules are often trapped
focally in the periphery of the lesion.
Prognosis and predictive factors
Most cases of mammary haemangiopericytoma
have been benign. There is
no well documented example of metastatic
disease or even re c u r rence {118,
1415,2855,2889}. Wide local excision
rather than mastectomy is often sufficient
for complete tumour excision.
Epidemiology
The clinicopathological spectrum of mamm
a ry pseudoangiomatous stromal hyperplasia
(PASH) extends from insignificant
m i c roscopic changes, often associated
with either benign or malignant breast disease,
to diffuse involvement of the bre a s t
or cases where a localized palpable or
non-palpable breast mass is pro d u c e d
(nodular PASH) {1275,2270,3037}. The
latter is uncommon and re p o rted to occur
in 0.4% of breast biopsies {2270}. Focal or
multifocal PASH without mass form a t i o n
has been re p o rted in 23% of breast biopsies,
usually as an incidental finding.
PASH has been re p o rted in at least 25%
of cases of gynaecomastia {157,1865}.
Aetiology
The immunophenotype of the proliferating
cells confirms that PASH is of myofibroblastic
origin {1113,2279,2510,3249}.
The pseudoangiomatous spaces are
also discernible in frozen sections, indicating
that they are not a fixation artefact
{157,3037}.
Clinical features
Nodular PASH usually present as a
painless, well circumscribed, mobile
palpable mass, clinically indistinguishable
from fibroadenoma {532,1275,
2270,2279,3037,3249}. Smaller lesions
may be detected by mammography
{532, 2270}. On imaging, nodular PA S H
is indistinguishable from fibro a d e n o m a
{2270}. Diffuse lesions are an incidental
finding {1275}. Bilateral lesions may
occur {157}. Rapid growth has been
re p o rted {532,2270,2765,3026}.
Macroscopy
Macroscopically, nodular PASH is usually
indistinguishable from fibroadenoma
ranging in size from 1 to 17 cm. The cut
surface is pale tan-pink to yellow {92,
1275,2279,2622,3037}.
Histopathology
PASH may be present in normal bre a s t
tissue or in various benign lesions {867,
90 Tumours of the breast