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| Adenomyoepithelioma of breast in an adolescent patient |
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Pritika Kushwaha1, Garima Rakheja1, Parul Tanwar1, Nita Khurana1, Vijay Kumar2
1 Department of Pathology, Maulana Azad Medical College, New Delhi, India
2 Department of Surgery, Lal Bahadur Shastri Hospital, New Delhi, India
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| Date of Submission | 23-Dec-2021 |
| Date of Decision | 03-Feb-2022 |
| Date of Acceptance | 04-Feb-2022 |
| Date of Web Publication | 27-Jan-2023 |
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 Case Report | |  |
An 18-year-old female patient presented with left breast swelling for five months. The swelling was initially noticed as a small lump but progressively increased in size. There was no pain, skin change, or nipple discharge. Also, no associated axillary or neck swelling was noted. She had no significant medical past history or family history.
FNAC was performed. However, on repeated aspirations, the yield was scant, and a definite diagnosis was not possible. The patient was undertaken for lumpectomy. Grossly, the specimen was grey-brown globular measuring 6 × 5 × 3 cm. The cut section was grey-white and solid. No areas of hemorrhage or necrosis were noted [Figure 1]. Microscopic sections revealed a tumor composed of solid nests of myoepithelial cells proliferating around compressed tubules, and surrounded by fibrous connective tissue septa of varying thicknesses. There was occasional mitosis and no pleomorphism [Figure 2]a. The presence of myoepithelial cells was confirmed by immunohistochemistry, which showed cytoplasmic immunoreactivity for smooth muscle actin (SMA) and cytoplasmic and nuclear immunoreactivity for S100 whereas the lining epithelial cells of tubules expressed epithelial membrane antigen (EMA) [Figure 2]b, [Figure 2]c. Based on these findings, a diagnosis of Adenomyoepithelioma (lobular pattern) was given. | Figure 1: Gross appearance of the lumpectomy specimen showing a nodular grey white growth with irregular borders. A cut section is solid with few slit-like areas (inset)
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 | Figure 2: (a) Hematoxylin and Eosin stained section showing solid nests of myoepithelial cells proliferating around compressed tubules; and surrounded by fibrous connective tissue septa of varying thicknesses (Hematoxylin and Eosin stain 400×); (b) Immunohistochemical staining with SMA highlighting the proliferating myoepithelial cells (600×) (c) Immunohistochemical staining with EMA highlighting the presence of epithelial proliferation (600×)
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| Discussion | | |
Adenomyoepithelioma of the breast is a rare tumor with only around 150 cases reported in the literature to date. It predominantly affects middle-aged and elderly females. The age range is very wide (22 to 92 years), with the youngest reported case so far being 16 years. Only rare cases have been described in males.[1]
It morphologically presents as a solitary, firm, well-circumscribed nodular mass, ranging from 0.5 cm to 7 cm at its greatest diameter but may have irregular, pushing borders. Very large tumors may have central necrosis and dystrophic calcification.[2]
The hallmark of diagnosis of AME is the presence of biphasic cellular elements and the overall architecture of the tumor in histology along with its typical immunohistochemistry. Immunohistochemical stains include the diffuse positive reaction of epithelial cells with antibodies to cytokeratins (CK-AE1/3), CAM 5.2, or CK7, EMA, whereas myoepithelial cells show strong immunoreactivity to p63, smooth muscle myosin heavy chains, calponin, smooth muscle actin, S100, CK5/6, and CD10.[3]
On the basis of their histological growth pattern and cell type, AME has been classified as tubular, lobular, and spindle-cell types depending on the relative amounts of proliferating glandular and myoepithelial cells. The tubular pattern exhibits a balanced proliferation of rounded tubules and prominent hyperplastic myoepithelial cells. The spindle cell type is predominantly composed of spindled myoepithelial cells along with a few columnar, epithelial-lined tubules. The lobular pattern is composed of prominent myoepithelial cells forming solid nests proliferating around compressed tubules.[4]
The differential diagnosis includes benign lesions with prominent myoepithelial cells as in intraductal papilloma, pleomorphic adenoma, adenoid cystic carcinoma, and invasive mammary carcinomas. Intraductal papilloma with a more solid appearance and prominent myoepithelial cells in the fibrovascular core may be mistaken for adenomyoepithelioma. But the diagnosis of AME is favored if the myoepithelial proliferation is diffuse and extensive. A pleomorphic adenoma may contain prominent proliferating myoepithelial cells; however, these also typically contain foci of the hyaline matrix with prominent areas of chondroid differentiation. Also, they lack the biphasic proliferation of the glandular and myoepithelial components seen typically in adenomyoepithelioma. Adenoid cystic carcinoma can be recognized by its typical features, fenestrated epithelial nests composed of basaloid cells, and glandular luminal cells surrounding hyaline basement membrane material. However, occasionally it may even occur in association with adenomyoepithelioma. Adenomyoepithelioma may be mistaken for invasive mammary carcinoma, especially on core needle biopsy samples. Characteristic nuclear spindling and whorling growth patterns of myoepithelial cells with regularly spaced glands, supported by immunohistochemical data, should help with the diagnosis.[2]
Differential diagnosis should also include intraductal hyperplasia and nipple adenoma. A diagnosis of AME is favored if myoepithelial proliferation is extensive and involves the lesion diffusely. In nipple adenoma presence of florid ductal hyperplasia and the characteristic pseudo-invasion of surrounding breast parenchyma without fibrous hyalinised stroma are helpful features for differentiation. Other tumors that should be included in the differential diagnosis are fibroadenoma, phyllodes tumor, or tubular adenoma with AME-like areas, ductal adenoma, nodular adenosis, clear cell carcinoma, microglandular adenosis. Adenomyoepithelioma may be differentiated from a clear cell carcinoma by the presence of both epithelial and myoepithelial cell types, which can be confirmed from immunohistochemistry.[2] Microglandular adenosis is characterized by the absence of both the myoepithelial layer as well as S100 positivity.[5]
Because of the heterogeneity of adenomyoepithelioma, the diagnosis should be made only on those lesions that do not typically fit into traditional categories. Although immunohistochemical stains can be used in support of the diagnosis, they should not be viewed in isolation. The overall architecture is of utmost importance, which is why it is difficult to diagnose such lesions on core or incisional biopsy.[2]
The majority of the cases of adenomyoepithelioma are benign but local recurrence can occur. Malignant change has been reported in around 40 cases and distant metastases even more rarely.[1] In malignant adenomyoepithelioma, the malignancy can arise from either of the epithelial or myoepithelial components or even from both of the components in extremely rare cases. Features of malignancy include features such as the presence of marked nuclear pleomorphism, mitosis, necrosis, and invasive growth pattern. Overgrowth of either of the two components of the lesion indicates malignancy arising in an adenomyoepithelioma.[4]
The management protocol of both benign and malignant tumors consists of surgical removal. Local recurrence can occur if the margin of excision is not adequate or if there is incomplete excision. The prognosis of benign and locally recurrent tumors is good however, that of metastatic malignant adenomyoepithelioma is poor, thus far, with reported survival of a few months only.[1]
Thus, to conclude, the identification of characteristic architecture biphasic cellular elements in combination with immunohistochemistry is of utmost importance to establish a correct diagnosis.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | | |
| 1. | Bajpai J, Punatar SB, Gupta A, Badwe R, Gupta S. Bilateral adenomyoepithelioma of breast. J Can Res Ther 2013;9:523-5.  [ PUBMED] [Full text] |
| 2. | McLaren BK, Smith J, Schuyler PA, Dupont WD, Page DL. Adenomyoepithelioma: Clinical, histologic, and immunohistologic evaluation of a series of related lesions. Am J Surg Pathol 2005;29:1294-9. |
| 3. | Tamura G, Monma N, Suzuki Y, Satodate R, Abe H. Adenomyoepithelioma (myoepithelioma) of the breast in a male. Hum Pathol 1993;24:678-81. |
| 4. | O'Neil M, Fan F, Damjanov I. Adenomyoepithelioma of the breast. Laboratory Med 2008;39:477-80. |
| 5. | Yoon JY, Chitale D. Adenomyoepithelioma of the breast: A brief diagnostic review. Arch Pathol Lab Med 2013;137:725-9. |
Correspondence Address:
Parul Tanwar,
Department of Pathology, Maulana Azad Medical College, New Delhi - 110 002
India
 Source of Support: None, Conflict of Interest: None DOI: 10.4103/ijpm.ijpm_1240_21
[Figure 1], [Figure 2] |
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