Case Report
Mammary Myofibroblastoma: Case Report and Review of the Literature
Eiman Al Shammri, Hassan Al Ahmadi, Abdullah Abdrabalnabi, Arwa Al Ghamdi, Weddad Bagatada, Areej Al Nemer and Maha Abdel Hadi*
Department of Breast Surgery, Radiology and Pathology, King Fahd Hospital of the University, Imam Abdulrahman bin Faisal university, KSA
*Corresponding author: Maha Abdel Hadi, Department of surgery, Breast division, King Fahd hospital of the University, P.O. Box 40293, Al-Khobar 31952, KSA
Published: 14 Sep, 2018
Cite this article as: Al Shammri E, Al Ahmadi H,
Abdrabalnabi A, Al Ghamdi A, Bagatada
W, Al Nemer A, et al. Mammary
Myofibroblastoma: Case Report and
Review of the Literature. World J Surg
Surgical Res. 2018; 1: 1052.
Abstract
Benign breast diseases are still considered the largest comprise of breast complaints in developing
countries. They range from developmental abnormalities, inflammatory lesions, fibrocystic changes,
stromal lesions, and neoplasms. Mammary Myofibroblastoma (MMF) is a rare well defined benign
stromal tumor that found in both males and females. The rarity of the tumor along with its wide
morphological variation challenges the accurate identification of the final histopathological
diagnosis.
We present a case of a 70 years old female with 10 years history of an enlarging painless breast mass.
Breast ultrasound, Mammography and MRI have demonstrated its benign nature of the large breast
mass, yet the histopathology diagnosis was challenging based on the Core biopsy. It was reported as
MMF. Complete surgical excision was performed with ease leaving the normal compressed breast
tissue.
Introduction
MMF or myogenic stromal tumor is a rare benign breast mesenchymal tumor. It is usually
found in older males and postmenopausal females as a well-circumscribed painless breast mass that
seldom exceeds 3 cm. occasionally it may be incidentally discovered during surgery.
It is recognized as soft tissue tumor that arises from stromal elements giving it the ability to
affect many tissues such as the breast, skin, lymph nodes and suprasellar regions of the brain [1].
When found in the breast it is labeled as “Mammary-type Myofibroblastoma”.
It is composed of fascicles of spindle cells having features of myofibroblasts, spindle cells with
intervening hyalinized collagenous\myxoid stroma and a variably prominent component of adipose
tissue. The spindle cells characteristically express both CD34 and desmin.
In females, the diagnosis is always challenging due to the wide range of differential diagnoses.
Despite the limited follow up no recurrence was reported [2].
Case Presentation
A 70-year-old Saudi female, a known case of controlled hypertension with no history of other
co- morbidities presented with history of a left painless palpable breast mass for 10 years. The mass
started as a small nodule which progressively increased in size with no associated symptoms apart
from increased size of the affected breast and heaviness. Clinical examination revealed unremarkable
general examination, local examination showed obvious asymmetry between the two breasts with
no evidence of skin or nipple changes. The left breast with enlarged with a 11 cm × 12 cm painless,
soft, well-circumscribed, round mass almost occupying the whole anterior breast. There were no
palpable axillary nodes. The right breast was within normal limits.
The patient underwent series of specific imaging investigations which included, Ultrasound,
Mammogram, contrast enhanced mammogram and breast MRI followed by core biopsy.
Ultrasound was reported an avascular heterogeneous hypoechoic mass occupying most the left
breast (Figure 1).
Diagnostic mammogram showed a unifocal large well-defined macro-lobulated dense mass
occupying predominantly the upper most of the anterior and mid breast that is surrounded by
rim of lucency. No associated suspicious microcalcifications or architectural distortion or skin
thickening. No enlarged axillary lymph nodes were noted (Figure 2).
MRI also confirmed the benign nature of the large 11 cm × 9
cm × 10.7 cm, well-circumscribed lobulated mass. Based on the
Radiological findings it was collectively reported as BIRAD IV.
Core biopsy showed the spindle cells infiltrating the dense fibrous
tissue in both linear and curvilinear arrays. Nor mitosis or necrosis
was identified. Immunostaining reported Positive estrogen and
progesterone receptors, and HER2 negative with Ki 67 5% (Figure
3a-3d).
Surgical excision of the mass of the mass was performed.
Intraoperative findings demonstrated a well capsulated soft tissue
mass with large tortuous blood supply running along the peripheral
surface of the lesion. The lesion shelled from the compressed noninfiltrated
breast tissue with ease.
The diagnosis was confirmed with further staining which showed
desmin, calponin, CD34, (Figure 4a,4b).
The patient underwent smooth postoperative recovery and
was discharged with regular outpatient follow up with no recorded
complications or recurrence in six months follow up.
Figure 1
Figure 1
Ultrasound was reported an avascular heterogeneous hypoechoic
mass occupying most the left breast.
Figure 2
Discussion
MMF is a rare entity that was first described as a distinct benign
mesenchymal breast lesion by Wargotz et al. [1]. It gained the term
mammary type-Myofibroblastoma after challenging diagnosis based
on diligent staining to exclude other possible differential diagnoses,
and thus was recognized [3].
MMF is reported in both males and post-menopausal females
with an average age of 63 years. The average size at diagnosis is
around 3 cm; however, larger sizes have also been reported. It has
non-specific clinical and radiological characteristics and usually
presents as a single painless, non-tender mass that has the tendency
to increase in size [1,3]. Diagnostic imaging have reveals it's well
demarcated nature however a variety of differential diagnoses of
other well circumscribed lesions such as phyllodes tumor, Pseudo
Angiomatous Stromal Hyperplasia (PASH) or atypical fibroadenoma
should be differentiated [4]. The point of differentiation is the total
absence of epithelial elements in MMF.
In females, the wider range of differential diagnoses usually
hinders the quick and accurate identification of this unusual entity
[5].
Histologically the classical picture is of a well demarcated but
not encapsulated tumor borders composed of bland spindle cells
running in fascicles separated by thick hyalinized collagen bundles.
The neoplastic cells have slightly eosinophilic cytoplasm and oval
nuclei with conspicuous small nucleoli. Typically, the tumor has low
mitotic activity and there is no evidence of necrosis, atypical mitosis
or entrapment of mammary epithelial tissue [1-3].
Nevertheless, more histological variations were also reported.
Detailed contemporary morphological review revealed variants
of MMF including classic, myxoid, lipomatous, epithelioid and
deciduoid, along with the differential diagnoses of each type, and
emphasizing the importance of recognizing MMF with all its variants
[4].
MMF may mimic many stromal lesions rendering the diagnosis
challenging. Reported cases of MMF imitating invasive lobular
carcinoma, Schwannoma and metaplastic carcinoma by H&E stain.
This confusion commonly resolved by immunohistochemical profile
[5,6]. Immunohistochemistry may show tumor cells are positive
for CD34 and desmin in approximately 89% and 91% of the cases;
respectively. Tumor has been reported to be positive for BCL-2, CD99
and Smooth Muscle Actin (SMA). Other immunohistochemical
markers that may aid in the diagnosis include Pan-cytokeratin and
S100; both are typically negative in the neoplastic cells [2].
The well-circumscribed nature of the lesion coupled with the low
proliferation index and absence of marked nuclear pleomorphism
favors the benign diagnosis.
Pseudo Angiomatous Stromal Hyperplasia (PASH) can seldom
be confused with MMF since a well-defined mass rarely occurs [7].
It should be emphasized that MMF may occur at different
sites. Clinicians should keep the diagnosis in mind when they are
confronted with lesions of the prostate, liver, vulva and the groin/
inguinal region [8,9].
Multimodality imaging techniques aid in the diagnosis. Mammary
MMF is the most disclosed lesion due the breast screening programs,
the availability of imaging modalities and the ease of accessibility to
the affected tissue [10].
This presented case revealed the benign nature of the disease from
the long history and clinical presentation. The lack of pain and other
local symptoms precluded the early presentation. Large size breast
lesions may equally be reported in male patients [10,11].
Despite the benign nature of the lesion, the recognition and
surgical excision should be performed. Pressure on vital structures
such as the brain may cause unwarranted outcomes. In the Breast
local surgical excision is the treatment of choice.
Figure 3a-3d
Figure 3a-3d
H&E slides (a: × 4 magnification, b: × 10 magnification c: ×
20 magnification, d: × 40) showing a well-demarcated cellular neoplasm with
pushing borders. It is composed of bland spindle cells, eosinophilic cytoplasm
running in fascicles separated by thick eosinophilic collagen bundles; cells
have an ovoid to elongated nuclei with mild nuclear polymorphism and
conspicuous nucleoli.
Figure 4
Conclusion
MMF is a challenging histological diagnosis. Surgical excision is the treatment of choice. No Adjuvant treatment is required.
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