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 Table of Contents  
CASE REPORT
Year : 2019  |  Volume : 6  |  Issue : 4  |  Page : 265-267

Accurate diagnosis and sub categorization of benign adenomyoepithelioma of the breast-tubular type: A challenge on core needle biopsy


1 Department of Pathology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry; Department of Pathology, Kalinga Institute of Medical Sciences, KIIT University, Bhubaneswar, Odisha, India
2 Department of Pathology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India
3 Department of Pathology, Jawaharlal Institute of Postgraduate Medical Education and Research; Department of Pathology, Mahatma Gandhi Medical College and Research Institute, Puducherry, India
4 Department of Surgery, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India

Date of Submission12-Jun-2018
Date of Decision04-Sep-2018
Date of Acceptance30-Sep-2018
Date of Web Publication21-Nov-2019

Correspondence Address:
Arun K Kumar
Department of Pathology, Mahatma Gandhi Medical College and Research Institute, Puducherry - 607 402
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/cjhr.cjhr_86_18

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  Abstract 


Adenomyoepithelioma (AME) is a biphasic myoepithelial tumor with poorly understood histogenesis. Most of these cases have a benign course. They can cause major diagnostic dilemmas, particularly on core needle biopsy. Here we report of a case of a benign adenomyoepithelioma in a fourty-four year old female who presented with hard breast lump, which highlights the diagnostic difficulties encountered on conventional histopathology and the importance of immunohistochemistry in differentiating them from their mimics.

Keywords: Breast, calponin, cytokeratin, myoepithelial, p63


How to cite this article:
Pradhan P, Mohan S, Kumar AK, Gochhait D, Toi PC, Sadasivan J. Accurate diagnosis and sub categorization of benign adenomyoepithelioma of the breast-tubular type: A challenge on core needle biopsy. CHRISMED J Health Res 2019;6:265-7

How to cite this URL:
Pradhan P, Mohan S, Kumar AK, Gochhait D, Toi PC, Sadasivan J. Accurate diagnosis and sub categorization of benign adenomyoepithelioma of the breast-tubular type: A challenge on core needle biopsy. CHRISMED J Health Res [serial online] 2019 [cited 2019 Dec 14];6:265-7. Available from: http://www.cjhr.org/text.asp?2019/6/4/265/271337




  Introduction Top


Adenomyoepithelioma (AME) is a biphasic myoepithelial tumor with poorly understood histogenesis. Most of these cases have a benign course, though malignant transformations do occur.[1],[2] owing to their rarity, they may not be considered as a possibility at the outset. They can cause major diagnostic dilemmas, particularly on core needle biopsy. Here, we report a case of a benign tubular type of AME, which highlights the diagnostic difficulties encountered on conventional histopathology and the importance of immunohistochemistry in differentiating them from their mimics.


  Case Report Top


A 44-year-old female presented with the complaints of right breast lump for 6 months followed by intermittent pain for 3 months. No history of the increase in the size of the swelling or nipple discharge or ulceration or retraction was noted. There was no antecedent trauma to the breast or any known comorbidities. She attended menarche at 18 years of age followed by regular menstrual cycles. She had three full-term normal deliveries, the last childbirth being 17 years back. There was no family history of any malignancy in the family.

On general examination, she was conscious, oriented, and afebrile. Pulse rate was 80/min, and blood pressure was 130/90 mm Hg. Local examination revealed a 4 cm × 3 cm lump in the upper inner quadrant of the right breast, which was nontender, hard in consistency, mobile with a nodular surface. It was neither fixed to the overlying skin nor the underlying chest wall. There was no nipple discharge. The contralateral breast was found to be unremarkable. There was no axillary lymphadenopathy on either side. Per abdomen examination was soft. Other system examinations were within normal limits. Mammography was not done.

Routine laboratory investigations showed hemoglobin of 11.4 g% and total leucocyte count of 6620/cu. mm. (neutrophils 54%, lymphocyte 40%, eosinophils 3%, and monocyte 3%). Platelet count was 2.62 lakh/cu. mm. Blood sugar, urea, and creatinine levels were found to be 79 g/dl, 16 g/dl, and 0.9 g/dl, respectively.

Core needle biopsy was performed on the lump yielding four fragmented cores of breast tissue. Sections showed an encapsulated tumor comprising predominantly monotonous spindle cells in no particular pattern. These cells predominantly of spindle shape with elongated oval to plump hyperchromatic nuclei with scant to moderate eosinophilic cytoplasm having indistinct cytoplasmic outlines showing minimal atypia. Although there was no mitosis or necrosis noted, on a careful assessment of the section a biphasic tumor was identified. The spindle cells were closely interspersed with a second component, the bland-looking glandular elements. These were composed of cuboidal cell lining showing moderate to the abundant eosinophilic cytoplasm. These were devoid of any atypia, mitosis, necrosis or pleomorphism. Given these findings possibility of a benign spindle cell tumor, favoring a fibroepithelial lesion was considered.

However, given the given age and hard nature of the mass, there was a high clinical suspicion of malignancy, for which a repeat biopsy from a different area was attempted which showed similar features. As there was classic biphasic morphology in both the biopsies, immunohistochemistry was performed. On immunohistochemistry, the glandular epithelium was highlighted by pancytokeratin while the spindle cells were positive for p63 [Figure 1]. As there were no clear cells, a diagnosis of benign ademyoepithelioma of spindle cell type was made.
Figure 1: (a) Section shows a linear core with a circumscribed tumor. (b) Section shows the tumor composed of biphasic population; spindled cells admixed with glandular epithelium. (c) Glandular elements showing Pancytokeratin positivity (×100, inset ×400). (d) Diffuse strong nuclear p63 positivity in the spindle cells (×100)

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A wide local excision was performed under general anesthesia. Intraoperatively, there was a 4 cm × 3 cm tumor in an upper inner quadrant of the right breast. Grossly, the specimen measured 6.5 cm × 5 cm × 5 cm. The outer surface showed attached fibro-adipose tissue. Cut surface of the specimen showed multiple well-circumscribed nodules ranging in size from 2 cm × 1 cm × 1 cm to 2.5 cm × 1.5 cm × 1.5 cm. The tumor was completely excised with adequate margins. Sections showed similar morphologic findings as noted on core biopsy but in addition, showed a good number of clear cells with foci of calcification. There was no atypia, increased mitoses, necrosis, or infiltration. On immunohistochemistry using p63 and pancytokeratin, similar biphasic nature of the tumor was re-confirmed, and a final diagnosis of benign AME tubular type was made [Figure 2].
Figure 2: (a) Gross picture of the excision specimen showing multiple well circumscribed nodules of solid, gray white tumor. (b) Scanner view showing the circumscription in the form of numerous fibrous septae dividing the tumor into lobules (H and E, ×40). (c and d) Sections showing the various spindle cells with the streaming unidirectional glandular elements, with no atypia, necrosis or increase in mitosis (H and E, [c] ×100, [d] ×400). (e) Glandular elements showing pancytokeratin positivity (×100, inset ×400). (f) The spindle cells showing diffuse strong nuclear p63 positivity (×100, inset ×400)

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Postoperatively, the patient recovered without any complications. She is currently on follow-up for the same and has been disease-free for the past 18 months.


  Discussion Top


AME is a biphasic myoepithelial tumor, classically described on histology as a balanced proliferation of the epithelial and myoepithelial elements in lobular aggregates. Although exact histogenesis is still poorly understood, it is postulated to arise from the myoepithelial cells in the background of benign proliferative breast disease. Most of these cases have a benign course, though malignant transformations do occur.[1],[2],[3] It has been a convention to subcategorize them into tubular type, lobulated, and spindle cell type in isolation or with overlapping features.[4] These tumors are documented between 26 and 76 years, located either peripherally or centrally in the breast parenchyma. They are usually well-circumscribed, having a nodular surface, firm- to hard in consistency, ranging in size between 1 and 15 cm.[5]

On core biopsies done for diagnostic purposes, these lesions pose great challenges in diagnosis as in the given case. When a core biopsy from any breast lump shows a preponderance of spindle cells, there is a multitude of benign as well as malignant differentials to be considered. The basic approach starts with deciding what the overall morphology favors depending on the cellularity, degree of atypia, pleomorphism, mitotic count, atypical mitoses with or without necrosis. In the presence of these findings on histopathology, we need to consider malignant differentials including malignant phyllodes, metaplastic carcinomas, adenosarcomas, malignant AME, and metastasis. When the morphology is bland then important benign differentials such as granulation tissue, fibroepithelial lesions (including benign phyllodes tumor and fibroadenoma), fibromatosis, benign AME, pseudoangiomatous stromal hyperplasia, and benign neural lesions are to be considered.[6],[7]

AME, as is exemplified in this case, show a marked heterogeneity in the intra-tumor morphology. This further gets compounded by sampling bias in case of core needle biopsies, leading to difficulty in accurate morphologic sub-categorization. In the present case, these possible factors have probably resulted in a paucity of the myoepithelial cells having clear cell morphology in the core needle biopsy, causing difficulty in differentiating it from the other fibroepithelial tumors like fibroadenoma and benign phyllodes. Furthermore, there was an erroneous subcategorization into a spindle-cell type AME rather than tubular type. The latter was diagnosed only on the subsequent excision specimen due to the good number of clear cell type, highlighting a prime limitation of core needle biopsy.[8]

As is highlighted in this case, immunohistochemistry proves to be of great help in differentiating this rare entity from its diverse benign and malignant mimics. There is a characteristic complementary expression of the myoepithelial and epithelial marker by the spindle cells and the glandular cells within the tumor, respectively. Markers for myoepithelial cells such as p63, calponin or S100 can be used along with epithelial markers like cytokeratin or epithelial membrane antigen, for accurate diagnosis.[8],[9]

Overall, the AME is an unusual tumor posing diagnostic issues, particularly on core-needle biopsy done for a diagnostic purpose. Awareness of such less common lesions and their mimics is very important to ensure a high index of suspicion. A meticulous search for the admixed epithelial components and algorithmic assessment of morphology and use of relevant immunomarkers, help in clinching the diagnosis and differentiating them from their benign and malignant differentials.[7]


  Conclusion Top


AME is, overall, a rare entity which shows the proliferation of both epithelial and myoepithelial elements. Owing to the biphasic morphology with intra-tumoral variation, it poses diagnostic difficulty in differentiating it from its mimics on core needle biopsies, warranting a high index of suspicion of the rare spindle cell lesions of the breast for accurate diagnosis and subtyping.

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 Top

1.
Loose JH, Patchefsky AS, Hollander IJ, Lavin LS, Cooper HS, Katz SM, et al. Adenomyoepithelioma of the breast. A spectrum of biologic behavior. Am J Surg Pathol 1992;16:868-76.  Back to cited text no. 1
    
2.
Tavassoli FA. Myoepithelial lesions of the breast. Myoepitheliosis, adenomyoepithelioma, and myoepithelial carcinoma. Am J Surg Pathol 1991;15:554-68.  Back to cited text no. 2
    
3.
Tan PH, Ellis IO. Myoepithelial and epithelial-myoepithelial, mesenchymal and fibroepithelial breast lesions: Updates from the WHO classification of tumours of the breast 2012. J Clin Pathol 2013;66:465-70.  Back to cited text no. 3
    
4.
Samanta DR, Senapati SN, Sharma PK, Mohanty AK. Adenomyoepithelioma of the breast. Hematol Oncol Stem Cell Ther 2009;2:364-6.  Back to cited text no. 4
    
5.
Qureshi A, Kayani N, Gulzar R. Malignant adenomyoepithelioma of the breast: A case report with review of literature. BMJ Case Rep 2009;2009. pii: bcr01.2009.1442.  Back to cited text no. 5
    
6.
Ünal B, Erdoǧan G, Karaveli FŞ. Step by step approach to rare breast lesions containing spindle cells. Springerplus 2015;4:678.  Back to cited text no. 6
    
7.
Tse GM, Tan PH, Lui PC, Putti TC. Spindle cell lesions of the breast – The pathologic differential diagnosis. Breast Cancer Res Treat 2008;109:199-207.  Back to cited text no. 7
    
8.
Yoon JY, Chitale D. AME of the breast: A brief diagnostic review. Arch Pathol Lab Med 2013;29:725-9.  Back to cited text no. 8
    
9.
Abd el-All HS. Breast spindle cell tumours: About eight cases. Diagn Pathol 2006;1:13.  Back to cited text no. 9
    


    Figures

  [Figure 1], [Figure 2]



 

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