Adenomyoepithelial Adenosis of Breast: A Rare Case Report
Bhaskar Mitra , Mallika Pal, Tarak Nath Saha, Ashok Maiti
Departments of Pathology, Midnapore Medical College, Paschim Medinipore, WEST BENGAL, INDIA
Keywords: Breast neoplasms, Adenosis, Myoepithelial tumor
Myoepithelial cells of the breast and their hyperplasia is found
in many benign conditions resulting in a spectrum of lesions of
myoepitheliosis to myoepithelial carcinoma. We present a rare case of
adenomyoepithelial adenosis in a 17-year-old female who presented
with a palpable right breast lump. Although considered benign,
adenomyoepithelial lesions have a high chance of recurrence due to
inadequate excision. Recurrence and even metastasis are therefore
important issues in the follow-up of adenomyoepithelial lesions.
Hyperplastic and neoplastic lesions of the breast usually
arise from atypical proliferation of epithelial cells1
Hyperplasia of myoepithelial cells is found in myoepitheliosis
to myoepithelial carcinoma2
adenosis of breast is a rare variant of adenosis, with
similarity to microglandular adenosis, contrary to the
presence of myoepithelial cells in significant number.
Adenomyoepithelial adenosis exhibits high proliferation
in both glandular and myoepithelial component with a
tendency to carcinomatous transformation2,3
. It can be
a well-circumscribed lesion or may consist of multifocal
randomly arranged ductules. The asynchronus hypertrophy
and alteration of epithelial and myoepithelial cells is a
characteristic of adenomyoepithelial adenosis4
. A case of
adenomyoepithelial adenosis is reported and discussed on
the basis of clinical, radiological, and pathological findings
in this article.
A 17-year-old female sought attention for her breast lump,
two months after her first notice. She was non-lactating.
Family history was noncontributory. Physical examination
revealed a single well-defined lump in the lower inner
quadrant of the right breast with no evidence of associated axillary lymphadenopathy and normal contralateral breast.
The tumor had a firm consistency. Routine laboratory test
results were all within reference range. Breast sonography
revealed a hypoechoic tumor with microcalcification.
Mammography showed an opaque mass with linear
microcalcifications and focal blurred margin in the right
breast. Excisional biopsy was performed as there is chance
of malignant change.
Gross examination of the surgical specimen disclosed a
well-delineated oval nodule that measured 2.7x2.2 cm
(Figure 1). All of the tissue was formalin fixed (10%) and
processed for paraffin sections. Sections were stained with
H&E and immunohistochemistry with alfa smooth muscle
actin and p-63 was done.
On light microscopic examination, the tumor was welldemarcated
and composed of biphasic proliferation of
glandular epithelial cells and surrounding myoepithelial
cells (Figure 2A). Proliferative epithelial cells displayed
tubular growth patterns. Prominent myoepithelial cells
with clear cytoplasm surrounding the ductal epithelial cells
were noted (Figure 2B,C). There was a prominent focal
hyperplastic myoepithelial cell layer with strikingly clear
cytoplasm. Both epithelial and myoepithelial cells were
blended without cytological atypia. Less than 1 mitosis /10
high power field (HPF) was noted in the mitotic activity. Foci of disorderly arranged glands with mild variation
in shape and size with eosinophilic secretion was noted.
Immunohistochemical staining of myoepithelial cells was
strongly positive (Strong staining pattern) for alfa smooth
muscle actin (Figure 3A,B) and for p-63 (Figure 3C,D).
Click Here to Zoom
|Figure 2: A) A well-demarcated tumor composed of biphasic
proliferation of glandular epithelial cells and surrounding
myoepithelial cells showing mostly tubular pattern (H&E; x10).
B,C) Proliferative epithelial cells displaying tubular growth
patterns with prominent myoepithelial cells with clear cytoplasm
around epithelial cells were noted (H&E; x40).
Click Here to Zoom
|Figure 3: A,B) Strong staining pattern for alpha smooth muscle actin of myoepithelial cells (SMA; x). C,D) Strong staining pattern for
p-63 of myoepithelial cells (p63; x).
The results further supported the existence of myoepithelial
cells around the glandular cells. The final diagnosis was
adenomyoepithelial adenosis. The resection margins were
free. Postoperative course was smooth and uneventful. No
additional treatment was performed.
The combined proliferation of epithelial and myoepithelial
cells is common in breast- e.g. papilloma and sclerosing
adenosis. In adenomyoepithelial adenosis, myoepithelial
proliferation is marked. Many lesions, namely, adenoid
cystic carcinoma, myoepitheliosis, pleomorphic adenoma,
adenomyoepithelial adenosis and adenomyoepithelioma,
are composed of myoepithelial cells. Adenomyoepithelial
lesions are commonly seen in the salivary gland, skin, and
. Myoepithelial cells are usually situated
between the luminal ductal epithelial cells and the basal
classified the myoepithelial lesions of
the breast as myoepitheliosis, adenomyoepithelioma, and
malignant myoepithelioma (myoepithelial carcinoma).
Tavassoli has proposed the term myoepitheliosis to describe
a process that in its typical form involves the peripheral duct
system and is characterized by subepitheilal proliferation
of round or spindle shaped myoepithelial cells. She also
subdivided adenomyoepitheliomas according to their cell
predominance as spindle cells, tubular, lobulated, and carcinoma arising in adenomyoepithelioma. Pia-Foschini
suggested that in spite of using the term apocrine
adenosis (adenomyoepithelial adenosis) these lesions can
be referred as tubular adenomyoepithelioma. Moinfar4
described adenomyoepithelial adenosis as a rare type of
adenosis with a predominance of myoepithelial component.
The tubules exhibit an increase in myoepithelial cell
infrequently showing enlarged nuclei and prominent
nucleoli. Apocrine or squamous metaplasia can be present2,4
As per Erel et al.8 in a 46-year-old female presenting with
a breast lump, excisional biopsy showed adenomyoepithelial
adenosis. Similarly, a case was reported by Kiaer et al.9 in a
46-year-old lady with an upper lateral quadrant right breast mass of 2-cm size and biopsy revealed adenomyoepithelial
adenosis. But in our case the patient is younger than the
previously reported cases.
In our case, the lesion, marked with cellular heterogeneity
and associated hypertrophy of epithelial and myoepithelial
cells, proves itself as benign in nature. So presence
of myoepithelial cells is very much important. In
immunohistochemical staining, cytoplasmic positivity
by SMA and nuclear positivity of p63 reinforces the
myoepithelial cells. In our case both markers showed Grade
IV staining pattern (Figure 4,5).
Adenomyoepithelial adenosis (AA) is histologically indistinguishable
from a small (microscopic) adenomyoepithelioma
(AME)4. In most described cases, (AA) blends with or surrounds an (AME). Mammary acini, with ductal epithelial
cells as inner lining and circumscribed, prominent,
phenotypically variant, and usually solid proliferating,
myoepithelial cells outside, are typical histological features
of a benign adenomyoepithelioma1. The myoepithelial
cells usually have clear cytoplasm with immunopositivity
for smooth muscle myosin, and actin10. Some show apocrine
snouts. Where as in AA, presence of focal proliferation
of myoepithelial cell with strikingly clear cytoplasm,
which is noted in our case, is usually observed. Histologicaly
the AA and microglandular adenosis (MA) are similar
and distinguished by absence of myoepithelial cells in the
latter. Tubular carcinoma with irregular tubules of varying
size, shape and distribution is also a in differential diagnosis.
The glands of the tubular carcinoma are larger than
those of MA and larger than those of AA and show characteristic
angular pattern. The lining cuboidal to columnar
cells show apical snouts but myoepithelial cells are absent.
Desmoplastic stroma, a hallmark feature of tubular carcinoma,
is absent in AA and MA11.
The prognosis of patients with adenomyoepithelial adenosis
of the breast is usually good. Behavior of this tumour is
uncertain; appear to have low malignant potential with a
tendency for local recurrence or rarely metastasis due to
failure to achieve a free resection margin. Therefore, it is
important to make an accurate pathologic diagnosis and
arrange proper management for this kind of rare breast
tumor. Further clinical and pathological investigations of
breast adenomyoepithelial adenosis may help to elucidate
the true nature of this rare tumor.
There is no conflict of interest related to the work in this
study. Written consent has been taken from the subject and
from her guardian.
The source of funding was Institutional funds of Midnapore
Medical College & Hospital, Paschim Medinipur.
1) Rosen PP. Adenomyoepithelioma of the breast. Hum Pathol.
2) Tsuda H, Mukai K, Fukutomi T, Hirohashi S. Malignant
progression of adenomyoepithelial adenosis of the breast. Pathol
3) Tavassoli FA. Myoepithelial lesions of the breast. Myoepitheliosis,
adenomyoepithelioma, and myoepithelial carcinoma. Am J Surg
4) Moinfar F. Adenosis. In: Moinfar F, editor: Essentials of diagnostic
breast pathology. Berlin: Springer; 2007. 31.
5) Tsuji N, Tateishi R, Ishiguro S, Terao T, Higashiyama M.
Adenomyoepitheloma of the lung. Am J Surg Pathol. 1995;
6) Sciubba JJ, Brannon RB. Myoepithelioma of salivary glands:
Report of 23 cases. Cancer. 1982;49:562-72.
7) Pia-Foschini M, Reis-Filho JS, Eusebi V, Lakhani SR. Salivary
gland-like tumours of the breast: Surgical and molecular
pathology. J Clin Pathol. 2003;56:497-506.
8) Erel S, Tuncbilek I, Kismet K, Kilicoglu B. Adenomyoepithelial
adenosis of the breast: Clinical, radiological, and pathological
findings for differential diagnosis. Breast Care. 2008;3:427-30.
9) Kiaer H, Nielsen B, Paulsen S, Sørensen IM, Dyreborg U, Blichert-
Toft M. Adenomyoepithelial adenosis and low-grade malignant
adenomyoepithelioma of the breast. Virchows Arch A Pathol
Anat Histopathol. 1984;405:55-67.
10) Rosen PP. Myoepithelial neoplasms. In Rosen PP, editor: Rosen’s
breast pathology. Philadelphia: Lippincott Williams and Wilkins;
11) Eusebi V, Foschchini MP, Betts CM. Microglandular adenosis,
apocrine adenosis, and tubular carcinoma of the breast.
An immunohistochemical comparison. Am J Surg Pathol.