2016, Volume 32, Number 1, Page(s) 047-050
Incidentally Discovered Extensive Squamous Metaplasia within Borderline Phyllodes Tumor: Presentation of a Rare Tumor
Nesrin UĞRAŞ1, Şahsine TOLUNAY1, Fatma ÖZ ATALAY1, Şehsuvar GÖKGÖZ2
1Department of Pathology, Uludağ University, Faculty of Medicine, BURSA, TURKEY
2Department of General Surgery, Uludağ University, Faculty of Medicine, BURSA, TURKEY
Keywords: Breast neoplasm, Phyllodes tumor, Metaplasia
Phyllodes tumors are uncommon biphasic fibroepithelial neoplasms
of breast, comprising less than 1% of all breast neoplasms. We
therefore aimed to present the case with its microscopic findings. In
this article, we report a 59-year-old female admitted to the general
surgery department with a rapidly, enlarging, palpable mass in right
breast. After histopathological examination, it was diagnosed as
borderline phyllodes tumor with extensive squamous metaplasia.
Metaplastic changes are infrequent in the stromal and epithelial
component of these tumors. Extensive squamous metaplasia within
phyllodes tumor is rare and may occur in benign, borderline and
Phyllodes tumors (PTs) are uncommon fibroepithelial
tumors, composing approximately 1% of breast tumors and
form 2%-3% of all breast fibroepithelial lesions1
tumors are biphasic breast neoplasms showing projections
of cellular stroma covered by epithelium and myoepithelium
into epithelial-lined cystic spaces and creating a leaf-like
. In the stromal and epithelial component,
metaplastic change is infrequent. Cartilaginous, osteoid
and lipomatous metaplasia sometimes can occur in the
stroma of PTs. However, in the lining epithelia, apocrine
and squamous metaplasia can occasionally be seen. Rarely,
ductal or lobular carcinoma in situ, invasive carcinoma may
arise in the epithelial component3
Herein, we presented a case of borderline phyllodes tumor
with extensive squamous metaplasia, and reviewed the
literature regarding suggested mechanisms for its etiology.
A 59-year-old female was admitted to the general surgery
department with a rapidly, enlarging, palpable mass in right
breast. Physical examination showed a palpable, mobile
mass 3,5 cm in diameter below the nipple of right breast
that was not fixed to overlying skin and surrounding tissues.
Mammography showed a mass with cystic area and
partially irregular borders separated from the adjacent
breast. Sonography revealed a 4x3 cm measuring, smooth
bordered, lobulated lesion. Ultrasound-guided percutaneous
biopsy was performed on this breast mass and pathologic
examination showed fibroepithelial lesion. For definitive
diagnosis surgical assessment and excisional biopsy are
recommended. Macroscopically, the resected specimen
was 6x5.5x4 cm in size and the cut surface showed smooth
bordered pale-tan mass, measured 4x3.5 cm, which had
a whorled appearance. Histologically, leaf-like structures
characterized areas with increased stromal component were
observed. The cells of stromal component showed minimal or moderate atypia. Five to six mitotic figures per 10 highpower
fields (HPF) were counted in the cellular areas of the
stromal component. Cellular stroma enclosing glandular
and cystic spaces lined by multilayered squamous cells
without evidence of atypical changes was also noted (Figure
). The cystic spaces filled with laminated keratin material
). Estrogen receptor (Figure 3
) and progesterone
receptor (Figure 4
) was strongly expressed in the epithelial
component. Ki67 proliferative index in the stromal component
was 22% (Figure 5
). By these histopathological and
immunohistochemical findings, the case was diagnosed as
borderline phyllodes tumor with cystic squmaous metaplasia.
The patient was treated by adjuvant radiotherapy
and hormonotherapy. Follow-up after one year showed no
evidence of recurrence or metastasis. Axillary lymphadenopathy
was not identified at one-year follow-up.
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|Figure 1: Squamous metaplasia within borderline phyllodes
tumor: Presence of multilayered squamous cells (H&E; x100).
Click Here to Zoom
|Figure 2: Squamous metaplasia within borderline phyllodes
tumor: Presence of cystic spaces filled with keratin material
Click Here to Zoom
|Figure 3: Estrogen receptor expressed in epithelial component
Click Here to Zoom
|Figure 4: Progesterone receptor expressed in epithelial component
Phyllodes tumors (PT) is a rare fibroepithelial neoplasm of
the breast, which can grows rapidly and create asymmetry
of the breast4
. These tumors rarely show aggressive
behavior. Clinically, patients present with mobile masses
having smooth borders. On histopathological examination,
characteristic findings of PTs are stromal hypercellularity
and a prominent intracanalicular growth pattern5
Cleft-like spaces and ducts are lined by two layered, ductal
epithelium in the inner surface and myoepithelial cells of
outward. PT is usually classified as benign, borderline or
malignant, according to histologic features, which are the
presence of stromal overgrowth, cellularity, margin status
and mitotic figure count in stromal cells5-8. The most
commonly used parameter to classifying PT is mitotic
figure counts4. If the number of mitotic figures is less
than 4/10 HPF PT is classified as benign, however if there
are more than 10 mitoses/10 HPF, the tumor is considered
having malignant potential. A borderline PT represents
intermediate microscopic findings9. In current case, 5-6/
HPF mitotic figures were counted, revealing a borderline
In the stromal and epithelial components of PT metaplastic
change is rare. In one of the reported PT series, stromal
metaplasia that included adipose and chondromyxoid
elements, malignant heterologous components, such as
osteosarcoma, rhabdomyosarcoma and liposarcoma was
presented in only 11(3.3%) of 335 cases. The epithelial
component may show a variety of appearances. Varying
degrees of usual-type epithelial hyperplasia was well
recognized in PT and epithelial squamous metaplasia was observed in 12 cases (3.6%), 5 of which revealed squamous
cysts10. Apocrine metaplasia had been also reported
in the epithelium of PTs7,11. Squamous metaplasia of
ductal epithelium, which occurs in benign, malignant and
borderline PTs, like our case, was found in about 10% of PTs3. Examination of cystic areas of squamous metaplasia by
aspiration may lead to a mistaken diagnosis of a squamous
cyst12. Excluding PTs, extensive squamous metaplasia in
breast as much as seen in our case had been reported only
in the epithelium of gynecomastia13 and benign breast
The development of squamous metaplasia in breast may
be similar to squamous lesions that are seen in the salivary
gland and the uterine cervix. The squamous change in the
breast was suggested to begin within the myoepithelial cell
layer, before eventually involving the entire acinus.15,16.
This myoepithelial origin of the metaplastic squamous
cells was supported by the immunohistochemical studies,
showing actin, vimentin, S-100 protein expression of
metaplastic squamous cells17.
In conclusion, as reported in current case, extensive cystic
squamous metaplasia is a rare feature in phyllodes tumors.
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