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.
Figure 1: Gross picture of the specimen.
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).
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.
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 adenomyoepithelioma[1]. The myoepithelial cells usually have clear cytoplasm with immunopositivity for smooth muscle myosin, and actin[10]. 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 MA[11].
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.
ACKNOWLEDGEMENT
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.
FUNDİNG SOURCE
The source of funding was Institutional funds of Midnapore
Medical College & Hospital, Paschim Medinipur.
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