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CASE REPORT Table of Contents   
Year : 2010  |  Volume : 53  |  Issue : 2  |  Page : 310-312
Myoepithelial carcinoma arising in an adenomyoepithelioma of the breast: A case report of a rare entity


Department of pathology, Rajiv Gandhi Cancer Institute and Research Centre, Sector-5, Rohini, Delhi-110 085, India

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Date of Web Publication12-Jun-2010
 

   Abstract 

Adenomyoepithelioma of the breast is a rare tumor. Malignant change arising in this lesion is infrequent and only a few cases have been reported. We discuss a case of a 56-year-old female presenting with a firm breast mass, which was interpreted as myoepithelial carcinoma arising in a background of adenomyoepithelioma, based on morphological and immunohistochemical studies. This case is being highlighted for its rarity and distinct morphological spectrum.

Keywords: Adenomyoepithelioma, breast, myoepithelial carcinoma, tumor

How to cite this article:
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

How to cite this URL:
Khurana A, Jalpota Y. Myoepithelial carcinoma arising in an adenomyoepithelioma of the breast: A case report of a rare entity. Indian J Pathol Microbiol [serial online] 2010 [cited 2019 Nov 12];53:310-2. Available from: http://www.ijpmonline.org/text.asp?2010/53/2/310/64296



   Introduction Top


Myoepithelial tumors are lesions either derived from, or composed of, a dominant to pure population of myoepithelial cells. [1] Various lesions described are myoepitheliosis, adenomyoepithelial adenosis, adenomyoepithelioma and malignant myoepithelioma (myoepithelial carcinoma), the latter two presenting as a palpable lump or on mammography as a hyperdensity or lobulated mass. [1],[2]

Adenomyoepithelioma is a rare tumor, mostly benign, characterized by biphasic proliferation of epithelial and myoepithelial cellular elements. Rarely malignant change can occur in one or both cellular components. [3],[4],[5]


   Case Report Top


A 56-year-old female presented with a complaint of lump in the right breast noticed 20 days prior to the presentation. There was no associated pain or any other symptom. Local examination revealed a firm to hard lump in the upper outer quadrant of the right breast. The nipple and overlying skin were normal. A mammographic and ultrasonographic evaluation of right breast revealed a relatively defined heterogeneous, hypoechoic, lobulated lesion in the right breast with slightly irregular margins. It was suggestive of a mitotic lesion and a cytological evaluation was advised.

Fine needle aspiration (FNA) revealed moderately cellular smears showing a distinct discohesive population of spindle-shaped pleomorphic malignant cells having marked nuclear atypia and moderate amount of cytoplasm. Also identified were a few tight cohesive clusters of bland epithelial cells with minimal pleomorphism [Figure 1]. Fine Needle Aspiration smears were reported positive for malignancy. The staging work-up showed no evidence of metastasis. Subsequently, the patient underwent a modified radical mastectomy with axillary clearance, and the breast tissue was sent to our department.

Gross examination showed a fairly circumscribed gray-white tumor, with pushing margins, measuring 2.5x2.4x2.3cm. The overlying skin, nipple and areola were all unremarkable and the margins and the base were grossly free of tumor. On microscopy, sections showed a lobulated tumor with two distinct morphological areas [Figure 2]. The predominant areas consisted of tightly packed tubules and ducts exhibiting proliferation of layers of myoepithelial cells, of clear cell type, around the normal epithelial-lined spaces. The adjoining areas showed sheets and fascicles of pleomorphic spindle cell population showing marked nuclear pleomorphism and brisk mitoses of 2-3 per high power field [Figure 3]. No typical areas of in situ component or invasive ductal carcinoma were identified in multiple sections studied. A diagnosis of adenomyoepithelioma with malignant transformation was made.

The immunohistochemical (IHC) studies were performed with a battery of epithelial and myoepithelial markers. The myoepithelial markers, namely, smooth muscle actin (SMA), smooth muscle myosin heavy chain (SMMH), p63, 34βE12, S-100 highlighted the prominent myoepithelial cells of adenomyoepitheliomatous component. In the malignant spindle cell areas, there was an expression of pancytokeratin (CK), CK5 along with co-expression of p63, S-100 and 34βE12 [Figure 4] and [Figure 5]. The spindle cells did not express SMA and SMMH and were negative for estrogen and progesterone receptors as well. The positivity of pancytokeratin with the co-expression of various myoepithelial markers helped us make the final diagnosis of myoepithelial carcinoma arising in the vicinity of adenomyoepithelioma. All 13 axillary lymph nodes isolated were free of tumor and showed reactive changes. The postoperative period was uneventful and later the patient was put on follow-up.


   Discussion Top


Myoepithelial cells are a normal component of breast tissue and may appear spindle shaped or as large ovoid cells sometimes with clear cytoplasm. These are immunoreactive for various markers like SMA, SMMH, p63, 34βE12, CK5, CK14, S-100 and caldesmin. Previously, the identification of myoepithelial cells in the lesion concluded benignity of the lesion per se. However, the trend of reporting of the mammary neoplasms, derived largely or entirely from the myoepithelial cells is on the rise. Tumors with bicellular proliferation of both epithelial and myoepithelial cells are called adenomyoepitheliomas. Though most of the adenomyoepitheliomas are benign, either of its two components may become malignant.

The evolution of malignant adenomyoepithelioma seems to begin with adenosis, with or without myoepithelial hyperplasia, advances to benign adenomyoepithelioma and proceeds to a possible malignant transformation. [4] Malignant myoepithelial tumors are either pure myoepithelial carcinoma or an adenomyoepithelioma with a component of myoepithelial carcinoma, epithelial carcinoma, sarcoma or a carcinosarcoma, the various transformations being highlighted by IHC. [1] Our case was diagnosed as myoepithelial carcinoma arising in an adenomyoepithelioma. Myoepithelial carcinoma component showed immunoreaction with Pan CK, p63, 34βE12, S-100 and CK5, however SMA and SMMH were negative. Immunohistochemically, myoepithelial cells stain variably to SMA. Cases of malignant myoepithelial tumors with focal expression or absence of SMA have been reported in the literature. [4],[6]

The review of 12 published cases of malignant adenomyoepitheliomas showed distant metastases in four cases with spread to lung and brain, evidence suggesting hematogenous spread being more common as compared to lymphatic spread. [4] Tumors with size 2 cm or larger have higher predilection for metastasis. [4],[7] These tumors have been reported in women, ranging in age from 26 to 76 years with tumor sizes varying from 1 to 15 cm. [4] Our case was 56-year-old and the tumor measured 2.5 cm in largest dimension with no evidence of nodal or distant metastasis. Pure myoepithelial carcinoma have aggressive clinical course with predilection for local recurrence and distant metastasis. [7],[8]

Myoepithelial lesions are generally benign but do have a spectrum of behavior with a potential for local recurrence and rarely distant metastases. Currently, surgery remains the mainstay of treatment for malignant myoepithelial lesions. A wide local excision with adequate margins is recommended. Both benign and malignant adenomyoepitheliomas are prone to local recurrence. The best predictor for benign adenomyoepithelioma is an initial incomplete or narrow excision margins. Because these tumors are so rare, available data concerning the prognosis of these tumors is scarce. Not much of is known about the natural history and clinical outcome of malignant adenomyoepithelioma.

 
   References Top

1.Tavassoli FA, Soares A. Tumours of the breast. In: World Health Organization Classification of Tumours of Breast and Female Genital Tract. Lyon: IARC Press; 2003. p. 86-9.  Back to cited text no. 1      
2.Howlett DC, Mason CH, Biswas S, Sangle PD, Rubin G, Allan SM. Adenomyoepithelioma of the breast. spectrum of disease with associated imaging and pathology. AJR Am J Roentgenol 2003;180:799-803.  Back to cited text no. 2  [PUBMED]  [FULLTEXT]  
3.Michal M, Baumruk L, Burger J, Manhalova M. Adenomyoepithelioma of the Breast with undifferentiated carcinoma component. Histopathology 1994;2:274-6.  Back to cited text no. 3      
4.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. 4  [PUBMED]  [FULLTEXT]  
5.Woo EK, James AD, Mercer J, Allan SM, Howlett DC. Myoepithelial carcinoma of the breast: A case report with imaging and pathological findings. Br J Radiol 2005;78:444-6.  Back to cited text no. 5  [PUBMED]  [FULLTEXT]  
6.Tamai M. Intraductal growth of malignant mammary myoepithelioma. Am J Surg Pathol 1992;16:1116-25.  Back to cited text no. 6  [PUBMED]    
7.Behranwala KA, Nasiri N, A'Hern R, Gui GP. Clinical presentation and long-term outcome of pure myoepithelial carcinoma of the breast. Eur J Surg Oncol 2004;30:357-61.  Back to cited text no. 7  [PUBMED]  [FULLTEXT]  
8.Fayaz MS, Samir SM, Amanguno HG, Adesina AO. Myoepithelioma (myoepithelial carcinoma) of the breast: Case report. J Clin Oncol 2008;26:617.  Back to cited text no. 8      

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Correspondence Address:
Anuj Khurana
98 SFS Flats, Phase-4, Ashok Vihar, Delhi-110 052
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0377-4929.64296

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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]

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