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CASE REPORT Table of Contents  
Ahead of print publication
Adenomyoepithelial adenosis mimicking phylloides: A diagnostic dilemma

1 Department of Pathology, King George's Medical University, Lucknow, Uttar Pradesh, India
2 Department of Endocrine Surgery, King George's Medical University, Lucknow, Uttar Pradesh, India

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Date of Submission21-Nov-2022
Date of Decision27-Nov-2022
Date of Acceptance29-Nov-2022
Date of Web Publication23-Mar-2023


Benign proliferative breast diseases are well recognized in young females. Benign biphasic proliferation of epithelial and myoepithelial cells has been observed, among which adeno-myoepithelial adenosis is one of the rare morphologies published in the literature with the tendency to recur and poses a risk for low-grade malignant transformation. Here, we report a case of a young female who had a history of recurrent breast lump mimicking phyllodes tumor and eventually diagnosed as adeno-myoepithelial adenosis on histopathological examination.

Keywords: Adeno-myoepithelial adenosis, adeno-myoepithelioma, phyllodes, recurrent breast tumors

How to cite this URL:
Singh J, Singhai A, Babu S, Singh K, Mishra A. Adenomyoepithelial adenosis mimicking phylloides: A diagnostic dilemma. Indian J Pathol Microbiol [Epub ahead of print] [cited 2023 Jun 1]. Available from:

   Introduction Top

In 1984, the term 'adeno-myoepithelial adenosis' was first mentioned by Kiaer H et al.[1] in a 46 years old female with breast lump. Later, it was also considered as a precursor lesion of low-grade malignant adeno-myoepithelioma breast.[2] Here, we report a rare case of adeno-myoepithelial adenosis in a 28 years young female presented with recurrent breast lump mimicking phyllodes and eventually diagnosed as adeno-myoepithelial adenosis.

   Case History Top

A 28 years old female presented with a history of recurrent breast lump three times in a period of 3 years in different quadrants of right breast. Previously, it was reported outside as benign phyllodes on core biopsy. She was operated for the third time in our institute, and we received a WLE specimen of right breast. Grossly, there was a large solitary, lobulated, gray-white solid growth with slit-like spaces measuring 10 × 7 × 5 cm in the retro-areolar area occupying the central part of breast [Figure 1]. Random sections were given from the growth and processed.

Microscopic examination revealed biphasic proliferation of luminal epithelial and abluminal myoepithelial cells in a haphazard pattern with intervening moderately cellular stroma [Figure 2]. There was no evidence of atypia in the cells lining the ducts, and there was no stromal overgrowth forming a leaf-like pattern. Immunohistochemistry using 34be12 was performed and revealed diffuse positivity in luminal epithelial cells within the ducts only. Ki67 showed minimal positivity in <5% of ductal cells [Figure 2]b. Because of a lack of circumscription with relatively less glandular components and atypia, this case was not labeled as benign adeno-myoepithelioma. Micro-glandular adenosis (MGA) and tubular carcinoma were also ruled out because of the absence of myoepithelial cells in these tumors. The final diagnosis was given as 'adeno-myoepithelial adenosis', the entity which is also mentioned previously in the literature.
Figure 1: Cut surface of the gross specimen showing a lobulated gray-white surface with slit-like spaces in between

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Figure 2: H and E stain, scanner view. Section from growth showing biphasic proliferating ducts in a haphazard pattern (a) H and E stain, high-power view of individual ducts. (b) Immunohistochemistry (34βe12). Section showing diffuse cytoplasmic positivity in luminal ductal epithelial cells. (c) Immunohistochemistry (Ki67). Section shows minimal to negative reaction in the ducts as well as stromal cells

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   Discussion Top

Benign diseases of breast comprise a heterogeneous group of fibrocystic and proliferating neoplasms. With prominent myoepithelial components, lesions of the breast were classified as myoepitheliosis, adeno-myoepithelioma, and myoepithelial carcinoma.[3]

Among these, adeno-myoepithelioma is an uncommon benign tumor comprising biphasic differentiation into ductal and myoepithelial cells with unknown etiology. However, adeno-myoepithelial adenosis has been observed to be associated with adeno-myoepithelioma and was considered as a precursor lesion.[4-8] It is a rare variant of adenosis minimally mentioned in the literature.[1-3]

Morphologically, it mimics MGA with a few evident exceptions such as predominant myoepitheliosis and an irregular glandular architecture which is not seen in MGA. Another differential diagnosis is tubular carcinoma in which there are relatively larger glands with characteristically angulated patterns. Myoepithelial cells are absent in tubular carcinoma.[9]

Clinically, it mimics other benign proliferative breast diseases. In the present case, it was mis-diagnosed as benign phyllodes even on core needle biopsy because of the presence of cellular stroma.

Prognostically, adeno-myoepithelial adenosis has a favorable outcome, but the behavior of this type of adenosis is uncertain with a high tendency for local recurrence and shown to have a low malignant potential.[9]

Immunohistochemistry with high-molecular-weight cytokeratins in adeno-myoepithelioma shows characteristic patterns with diffuse positivity in inner ductal epithelial cells and negativity in outer myoepithelial cells in this tumor (WHO Breast, 5th edition, vol 2).[10] In the present case also, a similar pattern of positivity was found in the proliferating ducts.

The present case is a relatively younger female with a larger size of tumor than reported in earlier cases, which indicates high variation in their clinical presentation.[1],[9],[11]

A very less recognized entity with variable morphological presentation and significant effects on the patient's management encouraged us to address this case.

   Conclusion Top

Adeno-myoepithelial adenosis is a rare benign proliferative morphology in breast with a high tendency for local recurrence and poses a risk for malignant transformation. Utmost care should be taken while dealing with recurrent benign breast tumors in young females for proper management and follow-up. Moreover, with such a high variation in their clinical and histomorphological presentation, awareness of this entity is much needed and it may be proposed as a significant individual category in WHO classification of breast tumors.

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.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Kiaer H, Nielsen B, Paulsen S, Sarensen IM, Dyreborg U, Blichert-Toft M. Adenomyoepithelial adenosis and low grade adenomyoepithelioma of the breast. Virchows Arch 1984;405:55-67.  Back to cited text no. 1
Tsuda H, Mukai K, Fukutomi T, Hirohashi S. Malignant progression of adenomyoepithelial adenosis of the breast. Pathol Int 1994;44:475-9.  Back to cited text no. 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. 3
Adenosis MF. In: Moinfar F, editor. Essentials of Diagnostic Breast Pathology. Berlin: Springer; 2007. p. 31.  Back to cited text no. 4
Eusebi V, Casadei GP, Bussolati G, Azzopardi JG. Adenomyoepithelioma of the breast with a distinctive type of apocrine adenosis. Histopathol 1987;11:305-15.  Back to cited text no. 5
Loose JH, Patchefsky AS, Hollander IJ, Lavin LS, Cooper HS, Katz SM. Adenomyoepithelioma of the breast. A spectrum of biologic behavior. Am J Surg Pathol 1992;16:868-76.  Back to cited text no. 6
Rosen PP. Microglandular adenosis. Am J Surg Pathol 1983;7:137-44.  Back to cited text no. 7
Zarbo RJ, Oberman HA. Cellular adenomyoepithelioma of the breast. Am J Surg Pathol 1983;7:863-70.  Back to cited text no. 8
Mitra B, Pal M, Saha TN, Maiti A. Adenomyoepithelial adenosis of breast: A rare case report. Turk Patoloji Derg 2017;33:240-3.  Back to cited text no. 9
Foschini MP, Geyer FC, Hayes MM, et al. Adenomyoepithelioma. In: Lokuhetty D, White AV, Watenabe Cree AI, editors. WHO Classification of Tumours: Breast Tumours. 5th ed. Lyon: IARC Press; 2019. p. 43-5.  Back to cited text no. 10
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.  Back to cited text no. 11

Correspondence Address:
Atin Singhai,
Postgraduate Department of Pathology, King George's Medical University, Lucknow, Uttar Pradesh 226003
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijpm.ijpm_925_22


  [Figure 1], [Figure 2]


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