IV. BENIGN AND MALIGNANT
EPITHELIAL AND NONEPITHELIAL TUMORS
A. Hamartoma
Hamartoma of breast is a circumscribed benign
nodule composed of variable amounts of fat, glandular
tissue, and fibrous connective tissue. Hamartoma is
usually, asymptomatic, but may become palpable with
increasing size and fibrous tissue giving firm
consistency. The majority occur in women over age 35
years.
Histologically, hamartoma consists of varying
amounts of adipose tissue, fibrous stroma, and
glandular tissue, some of which may be cystic.
Capsule may be complete or partial (Slide 48). An unusual
finding in the fibrous stroma is the presence of
capillary-like spaces, referred to as pseudoangioma (Slide 49).
Hamartoma of breast has distinct mammographic
features with circumscription and fat and soft-tissue
density surrounded by a thin radiopaque capsule or
pseudocapsule (Hessler et al). Pathologist unaware of
the mammographic findings may not use the term
hamartoma, but rather fibroadenolipoma and
lipofibroadenoma to indicate lesional components.
B. Vascular Tumors
Benign hemangiomas in the form of capillary,
cavernous and venous types rarely occur in the breast
parenchyma. These are benign, localized growth
without infiltration (Slide
50). The lining endothelial cells may appear
active, but nuclear atypia is absent. Thrombus
formation is common. Rarely the endothelial cells may
appear atypical with nuclear enlargement and
hyperchromasia. These atypical hemangiomas are small,
usually less than 2 cm and well circumscribed without
local infiltration.
Angiosarcoma is usually greater than 2 cm in size
and locally infiltrative with ill-defined borders.
Histologically, the angiosarcomas are divided into
well and poorly differentiated categories. In
well-differentiated angiosarcoma, the endothelial
cells form freely anastomosing, irregular vascular
channels, which are lined by flat endothelial cells
having enlarged hyperchromatic nuclei and occasional
mitotic figures (Slides 51
and 52). Sometimes
villous papillary formation occurs. Ill-defined
borders and local infiltration are essential
features. In biopsies, these characters may be absent
making correct diagnosis difficult.
In the poorly differentiated angiosarcoma the
malignant nature is apparent with anaplastic
endothelial cells forming complex vascular channels
or solid sheets (Slide 53).
The latter case often suggests a poorly
differentiated carcinoma. A correct diagnosis
requires immunohistochemical stain for Factor VIII or
endothelial cell markers.
Angiosarcoma of the breast has a tendency to
affect young women with a mean age of 34 years. The
typical presentation is a mass with bluish
discoloration of the overlying skin. (Rosen et al,
1988). Angiosarcoma is a highly aggressive tumor and
the total mastectomy is the preferred treatment. The
survival is closely related to the histologic grade.
The five-year disease free survivor rate is 76% for
low grade, well differentiated tumors and 70% for
intermediate grade and 15% for high grade, poorly
differentiated neoplasms (Rosen et al, 1988).
Postmastectomy angiosarcoma (lymphangiosarcoma)
occurs in association with lymphedematous upper
extremity following radical mastectomy. About two
thirds of the patients have also received radiation
to the axilla and the chest wall. The prognosis is
dismal.
C. Granular Cell Tumor
Granular cell tumor is a benign tumor initially
thought to be muscle origin by Abrikossoff in 1926
with the label of granular cell myoblastoma. Its
origin from Schwann cells is well-established by
electron microscopy and immunohistochemistry. About
6% of all granular cell tumors involve the breast.
The mean age at diagnosis is 40 years.
Granular cell tumors on clinical breast
examination simulate carcinoma with fixation to the
skin and rock hard on palpation.
The excised tumor strongly suggests carcinoma with
its firm consistency, gritty cut surface, and
ill-defined borders (Slide
54).
The most distinct histologic feature is the
abundant granular eosinophilic cytoplasm. Tumor cells
are arranged in bundles, cords and nests in a dense
fibrous stroma (Slide 55).
The nuclei are sometimes hyperchromatic, irregular,
and contain prominent nucleoli (Slide 56). Because of
these findings, granular cell tumor may be
misdiagnosed as apocrine carcinoma, especially on
frozen sections. However, mitotic figures are absent
or rare.
A complete local excision results in cure.
D. Stromal Tumors
Lipomas are circumscribed fat-containing lesions
which may occur anywhere within the breast. When
palpable, they are usually soft and freely movable.
Liposarcomas are extremely rare lesions that can
arise de novo or as malignant components within
phyllodes tumor. The myxoid stroma contains immature
lipoblasts with signet-ring appearance (Slides 57 and 58). Rare examples of
fibrosarcoma, malignant fibrous histiocytoma,
leiomyosarcoma, rhabdomyosarcoma, postradiation
sarcoma, chondrosarcoma (Slides
59 and 60),
osteosarcoma, and hemangiopericytoma have been
reported to occur in breast (Tavassoli, 1992). The
prognosis is dependent on the degree of
differentiation and the local extent of the disease.
V. NIPPLE DISEASES
Women with eczematous, erosive, pruritic changes of
the nipple should be biopsied promptly to distinguish
among chronic dermatitis, Paget's disease of the nipple,
and nipple adenoma (papilloma, papillomatosis).
A. Paget's Disease
Paget's disease results from an intraductal spread
of malignant cells to involve the nipple. About 1-2%
of breast cancer patients present with Paget's
disease. 50-60% of women have a palpable mass. Of
these 90% have underlying infiltrating ductal
carcinoma (Rosen and Oberman, 1993). 10-28% have no
clinical lesion.
The diagnosis is made by finding large cells with
pale, vacuolated cytoplasm, round to oval large
nuclei, prominent nucleoli migrating through the
epidermis. A highest concentration of Paget's cells
occurs in the basal and parabasal cell layers (Slide 61). The overlying
is sometimes hyperkeratotic, and chronic inflammation
is commonly seen in the dermis (Slide 62).
Paget's cells are positive with mucicarmine stain,
and express CEA, epithelial membrane antigen, milk
fat globule by immunohistochemistry.
95% or more have underlying in situ or invasive
ductal carcinoma in the breast or nipple (Slide 63). Rarely
carcinoma occurs in the lactiferous ducts just
beneath the skin. Paget's disease is not associate
with lobular carcinoma.
The underlying DCIS is usually comedo or solid
type, and the invasive carcinoma poorly
differentiated. In mastectomy specimens, 78% of
carcinomas have spread beyond the subareolar area.
Prognosis depends on the behavior and extent of
the underlying carcinoma.
B. Nipple adenoma or
papillomatosis
It is a ductal hyperplasia of the lactiferous
ducts, sometimes protruding onto the nipple surface
to manifest as a granular or ulcerated lesion.
Typical patients are 40-50 years of age.
Histologic appearance is usually a mixture of
intraductal papilloma, adenosis, and tubular glands,
which are lined by epithelial and myoepithelial cells
without nuclear atypia (Slides
64 and 65). Rare
mitotic figures may be seen.
This benign tumor coexists with breast carcinoma
in 16% of patients.
Nipple adenoma should be distinguished from
subareolar sclerosing papillomatosis which occurs
deeper in the breast tissue. Histologic appearance of
both lesions is similar.
C. Chronic Dermatitis
It is characterized by hyperkeratosis, spongiosis,
hyperplasia of the epidermis and chronic inflammation
of the underlying dermis (Slide
66)
VI. OTHER CHANGES
Fat Necrosis
Fat necrosis may mimic carcinoma with a mass,
pain, or skin retraction. It is associated with
trauma, surgical intervention, and radiotherapy. The
cause is unknown in some cases.
The excised lesion has a slightly firm consistency
in the periphery and golden brown color, soft,
sometimes liquified, material in the center.
Histologically fat necrosis is characterized by
irregular empty spaces, which are lined by foamy
histiocytes foamy histiocytes (Slide 67). The fatty acid
released by necrotic cells is removed by alcohol
during tissue processing resulting in empty spaces.
With time multinucleated giant cells,
lymphoplasmacytic infiltration, and fibrosis occur (Slide 68). Calcification
eventually deposits in fibrous tissue over a period
of several months.
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