| Adenosis
Increase in
the number of glandular elements.
Blunt
duct adenosis describes distorted or dilated acini with
a retained lobular architecture. Luminal cells of the ductule/acinus
may display columnar alteration and apical snouts.
In sclerosing
adenosis, compressed and distorted ductules have a pseudoinfiltrative
pattern. It is often associated with myoepithelial hyperplasia
and microcalcifications within a dense hyalinised stroma.
Nodular
adenosis/adenosis tumour is used to describe palpable
lesions of sclerosing adenosis.
Atypical
ductal hyperplasia
Histologic
appearances (both architectural and cytological) fall short of
of established criteria for DCIS. It resembles low nuclear grade
DCIS, and it associated with an increased risk of subsequent invasive
breast cancer development.
Atypical
lobular hyperplasia
Resembles
LCIS, but the features are not as fully developed. Also regarded
as a risk indicator of subsequent invasive breast cancer development
in both ipsilateral and contralateral breasts.
Calcifications
Deposition
of calcium phosphate or oxalate crystals in the breast, detectable
in mammograms. Histologic granular/amorphous-type calcifications
formed by deposition of calcium on nuclear debris are often present
in ductal carcinoma in situ with necrosis. These form linear,
branching patterns on X-rays. Radiologists use the American College
of Radiology Breast Imaging Reporting and Data System (BIRADS)
classification to describe calcifications.
Collagenous
spherulosis
A form of
benign structural alteration more commonly seen in ducts than
lobules.
There is epithelial hyperplasia and formation of glands and acellular
spherules creating a superficial resemblance to adenoid cystic
carcinoma.
Cyst
Common lesion
in the breast, thought to result from coalescence of lobular acini.
Diabetic
mastopathy
A self-limited
stromal abnormality of premenopausal women, usually seen with
insulin-dependent diabetes mellitus. The lesion is characterised
by collagenous stroma with keloidal features, and epithelioid
cells scattered amongst stromal spindle cells. Lymphocytes can
be seen clustered around blood vessels, lobules and ducts
Ductal
carcinoma in situ (DCIS)
Malignant
epithelial proliferation occupying duct spaces but confined within
the basement membrane.
It is a heterogeneous entity, radiologically, pathologically and
biologically.
Epithelial
hyperplasia
Increase in
the number of epithelial cells lining the duct/ductule.
In mild
epithelial hyperplasia, the epithelium is 3 to 4 cells thick,
excluding the myoepithelial cell layer.
In moderate epithelial hyperplasia, the epithelium
is 5 cell layers, and may form secondary luminal spaces.
In severe/florid epithelial hyperplasia, the ducts
are enlarged and nearly or completely filled by proliferating
epithelial cells.
Usual
epithelial hyperplasia refers to regular or ordinary
epithelial hyperplasia
Epitheliosis
Often used
to describe epithelial hyperplasia; seen as an almost solid benign
epithelial proliferation found predominantly in small ducts, ductules
and lobules.
Extensive
DCIS
Defined as
DCIS that comprises more than 25% of the main invasive tumour
mass, extending beyond it into the surrounding breast tissue;
or a tumour that shows invasion but is predominantly DCIS.
Fibroadenoma
A common benign
lesion, usually in young women. It consists of a proliferation
of both epithelial and stromal elements , with or without superimposed
changes of apocrine metaplasia, epithelial hyperplasia, sclerosing
adenosis and cyst formation
Fibrocystic
change
Morphological
features include cysts, usually with apocrine metaplasia.
Also referred to in the past as “fibrous mastopathy”, “mammary
dysplasia”, “fibrocystic disease”.
Grading
of invasive breast cancers
The Nottingham
histologic grade (modified Bloom-Richardson grading) is widely
used by pathologists. Three criteria namely extent of tubule formation,
nuclear pleomorphism and mitotic count are evaluated and each
given a score of 1 to 3. The final grade of the tumour is determined
by the sum of the scores.
Intraduct
Papilloma
Benign papillary
lesion arising from a major duct, often presenting clinically
with nipple discharge.
Lobular
carcinoma in situ (LCIS)
This lesion
is often encountered as a microscopic lesion that does not form
a palpable tumour. It is generally regarded as a risk indicator
rather than a direct precursor for subsequent invasive breast
cancer development in both ipsilateral and contralateral breasts.
Microinvasion
This term
is used in the setting of a dominant lesion of DCIS, in which
there are one or more separate foci of invasion of non-specialised
stroma, each invasive focus not measuring more than 1mm in maximal
diameter.
Mucocele-like
lesion
Composed of
mucin-containing cysts that may rupture and discharge secretions
into adjacent stroma, thus resembling the mucocele of salivary
gland origin. Its distinction from mucinous carcinoma can be problematic
at times. It can be associated with usual type hyperplasia, atypical
ductal hyperplasia or ductal carcinoma in situ.
Paget’s
disease
Lesion of
the nipple that clinically resembles an eczematous rash, thought
to be a manifestation of high nuclear grade, comedo DCIS affecting
subareolar ducts and extending into the epidermis.
An associated invasive breast carcinoma is seen in 35% to 50%
of affected patients.
Papillomatosis
Phyllodes
tumour
Also known
as cystosarcoma phyllodes, it occurs in an older age group than
fibroadenomas.
Histologically,
there is a leaf-like architecture with an exaggerated intracanalicular
growth pattern and increased stromal cellularity.
Benign,
borderline and malignant phyllodes
tumours are classified based on a constellation of histological
features that include the degree of stromal hypercellularity,
stromal atypia and mitotic activity, stromal overgrowth, invasive
versus pushing margins, necrosis, haemorrhage.
Pseudoangiomatous
stromal hyperplasia (PASH)
A lesion formed
by myofibroblasts, it shows anastomosing slit-like pseudovascular
spaces set in dense collagenous stroma. The myofibroblasts, highlighted
by CD34, line the margins of the spaces. Hormonal factors are
thought to influence its development.
Radial
sclerosing lesion
Also known
as radial scar, this proliferative lesion has a stellate configuration
radiologically and histologically, thus mimicking cancer. The
proliferative components, including duct hyperplasia, sclerosing
adenosis and cysts, are set in a central sclerotic zone of fibrosis
and elastosis. Stromal cellularity decreases in more mature lesions.
Terminal
duct lobular unit (TDLU)
Collection
of blind-ending ductules/acini (the lobule), together with the
terminal duct, embedded within loose specialised stroma.
Tubular
adenoma
Resembles
the fibroadenoma with the epithelial component, without accompanying
stromal proliferation.
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