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Year : 2011  |  Volume : 54  |  Issue : 1  |  Page : 230-232
Malignant adenomyoepithelioma: A tumor of low malignant potential despite basal phenotype


Department of Histopathology, Rajiv Gandhi Cancer Institute and Research Centre, Rohini, New Delhi - 110 085, India

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Date of Web Publication7-Mar-2011
 

How to cite this article:
Gandhi JS, Mehta A, Gupta G, Sardana M. Malignant adenomyoepithelioma: A tumor of low malignant potential despite basal phenotype. Indian J Pathol Microbiol 2011;54:230-2

How to cite this URL:
Gandhi JS, Mehta A, Gupta G, Sardana M. Malignant adenomyoepithelioma: A tumor of low malignant potential despite basal phenotype. Indian J Pathol Microbiol [serial online] 2011 [cited 2019 Nov 21];54:230-2. Available from: http://www.ijpmonline.org/text.asp?2011/54/1/230/77421


Sir,

Malignant adenomyoepithelioma is a rare neoplasm of breast with unknown biological behavior. It is characterized by bimodal proliferation of epithelial and myoepithelial cells, with distinct histomorphology and immunohistochemistry (IHC). [1],[2] In the literature, about 20 cases have been reported to have malignant change with evidence of distant metastasis in 4 of these. [3],[4] We report here, an unusual case of a malignant adenomyoepithelioma with advanced tumor stage and confounding IHC reactivity.

A 68-year-old lady presented with a right breast lump of 14 years with gradual increase in size for the last 6 months. On examination, there was a well-defined mass measuring 10 × 10 cm with shiny, indurated overlying skin. A mammography study demonstrated a suspicious, heterogeneous, hypoechoic, lobulated mass with irregular margins and bereft of microcalcification. Fine needle aspiration cytology was opined as malignant. On the basis of clinico-cytological features, a modified radical mastectomy was performed.

On gross examination, the tumor was firm to hard, lobulated with irregular margins and measured 6.5 × 5 × 4.5 cm. The cut surface was grey-white, nodular with pale yellow, friable foci of necrosis [Figure 1]. The overlying skin, nipple, and areola were all unremarkable. The tumor was mapped and studied according to the College of American Pathologist (CAP) guidelines. On microscopy, the tumor exhibited a lobular growth pattern composed of tubulo-glandular arrangement. These tubulo-glandular structures were lined by dual epithelium comprising outer myoepithelium and the inner luminal epithelium. These lobules were separated by pink hyaline-like collagenous material. Both the epithelial and myoepithelial cells exhibited high degree of pleomorphism, nuclear atypia, brisk mitosis, and areas of stromal invasion [Figure 2]. The surrounding breast showed an intraductal papilloma and foci of adenosis. The duality of the tumor was further reaffirmed by IHC which highlighted the outer myoepithelial cells with p-63, [Figure 3]c and S-100 proteins. The high-molecular-weight cytokeratin (34βE12) showed differential staining and decorated the luminal epithelium strongly and the myoepithelium weakly [Figure 3]a, which is contrary to the fact that it is a basal marker. Low-molecular-weight CK (CK7) [Figure 3]b and CD117 highlighted the inner luminal epithelium [Figure 3]d. Immunostains with SMMH were positive in the benign adenomyoepitheliomatous areas only. Immunostains for smooth muscle actin (SMA) were negative. The hormonal receptors were negative as expected.
Figure 1: Grossly the cut surface showed pale white lobulated tumor with irregular borders

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Figure 2: (a) Shows tubuloglandular structure with malignant clear cell myoepithelial cells emanating from them along with pink basement like material in between (H and E, ×100), (b) Shows concentric rows of malignant inner luminal epithelium and outer myoepithelium with brisk mitosis (arrow) (H and E, ×200). Inset (H and E, ×400), (c) Areas of necrosis (H and E, ×200)

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Figure 3: (a) High molecular weight cytokeratin (34βE12) showing strong staining in the inner luminal epithelium with comparatively weaker staining in the outer myoepithelium (DAB, ×200), (b) Low molecular cytokeratin (CK7) showing strong staining in the inner luminal epithelium with comparatively weaker staining in the outer myoepithelium. (DAB, ×200), (c) P-63 decorating the outer malignant myoepithelium. (DAB, ×400), (d) CD 117 decorating the inner luminal epithelial cells. (DAB, ×200)

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Benign adenomyoepithelioma of the breast is a rare tumor; malignant transformations described in about 20 cases, with patterns sub-classified as undifferentiated, myoepithelial or epithelial. A malignant transformation of both the components is extremely rare. The indexed case is being presented because of its long duration, unusually large size, with no metastasis and unusual IHC pattern. Hence, malignancy is a morphological attribute not necessarily reflecting the biological behavior of malignant myoepitheliomas. In our case, both the components stained with 34βE12 with stronger staining in luminal epithelial cells. Only p-63 and S-100 retained their fidelity for myoepithelium. Though the dual differentiation is evident, IHC showed overlapping patterns suggesting a duality of differentiation from a single clone. Since IHC is not highly distinctive, morphology remains the cornerstone of diagnosis of an adenomyoepithelioma. The present case expressed IHC markers of a basal phenotype but the behavior was not as aggressive as expected. [5] Finally, these tumors lack an in-situ component which translates to lack of micro-calcification on mammography.

To conclude, malignant adenomyoepitheliomas have a whimsical behavior with distinct histomorphology and IHC profile that may be confusing.


   Acknowledgement Top


Dr. Anuj Khurana, Department of Histopathology, Rajiv Gandhi Cancer Institute and Research Centre, Rohini, Delhi - 110 085, India.

 
   References Top

1.Ahmed AA, Heller DS. Malignant Adenomyoepithelioma of the Breast with malignant proliferation of epithelial and myoepithelial elements. A case report and review of literature. Arch Pathol Lab Med 2000;124:632-6.   Back to cited text no. 1
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2.Tavassoli FA, Soares A. Tumours of the breast. World Health Organization Classification of Tumours of Breast and Female Genital Tract. Lyon: IARC Press; 2003. p. 86-9.   Back to cited text no. 2
    
3.Choi SY, Kim JC, Kim SJ, Kim, Lucia KJ, Kim L, et al. Malignant Adenomyoepithelioma of the Breast Presenting as a Large Mass that Grew Slowly without Metastasis. J Breast Cancer 2009;12:219-22.  Back to cited text no. 3
    
4.Khurana A, Jalpota Y. Myoepithelial carcinoma arising in an adenomyoepithelioma of the breast: A case report of a rare entity. Indian J Pathol Microbiol 2010;53:310-2.  Back to cited text no. 4
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5.Rakha EA, Putti TC, Abd El-Rehim DM, Paish C, Green AR, Powe DG, et al. Morphological and immunophenotypical analysis of breast carcinomas with basal and myoepithelial differentiation. J Pathol 2006;208:495-506.  Back to cited text no. 5
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Correspondence Address:
Jatin S Gandhi
C-2-C/12/58, Janak Puri, New Delhi - 110 058
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0377-4929.77421

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    Figures

  [Figure 1], [Figure 2], [Figure 3]

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