Fine-needle aspiration biopsy of breast adenomyoepithelioma: A potential false positive pitfall and presence of intranuclear cytoplasmic inclusions

Malignant Adenomyoepithelial Tumour of the Breast - a Rare Diagnosis - Case Report

Breast adenomyoepithelioma is an unusual tumour characterized by a biphasic proliferation of epithelial and myoepithelial cells. Most of the breast adenomyoepitheliomas are considered to be benign and characterized by propensity for local recurrence. Malignant change can occur rarely in one or both cellular components. We here present a case of a 70-year-old previously healthy female who initially presented with a painless breast lump. The patient underwent wide local excision in view of suspicion of malignancy and sent for frozen section regarding the diagnosis and margins which surprisingly came as adenomyoepithelioma. Final histopathology came as low-grade malignant adenomyoepithelioma. The patient shows no sign of tumour recurrence in the follow up.

Malignant adenomyoepithelioma of the breast: A case report

•

Malignant breast adenomyoepithelioma (AME), rare subtype of cancer that usually benign.

•

Mastectomy and sentinel lymph node biopsy with no further recurrence.

•

Inner epithelial cells revealed positivity for CK5/6.

•

Myoepithelial layers were positive for P63, CK5/6, SMA and S100 protein.

•

Metastases chance of 30–40% with malignant adenomyoepithelioma, generally haematogenous route. Whereas metastases to the axillary lymph nodes is rare.

Introduction

Malignant breast adenomyoepithelioma (AME) is a rare subtype of breast cancer. AME is mostly a benign disease that uncommonly undergoes malignant transformation.

Presentation of case

Here we present a case of a young, previously healthy female who initially presented with a painless breast lump. The patient underwent wide local excision for atypical cells with squamous metaplasia by core biopsy, but final histopathology showed AME with carcinoma. Thus, a mastectomy and a sentinel lymph node biopsy was undertaken. The patient had an uneventful recovery and no recurrence after the second surgery.

Discussion and conclusion

Malignant transformation of adenomyoepithelioma is reported in a small number of cases. Benign AME may be treated with wide local excision as recurrence is rare locally. Whereas malignant AME tends to be treated with simple mastectomy with or without lymph node biopsy.

Tubular variant of mammary adenomyoepithelioma: Diagnostic challenges and cytomorphological correlation in two cases

The authors describe the cytomorphologic features of two cases of tubular variant of adenomyoepithelioma of the breast that were first examined by fine-needle aspiration cytology (FNAC) and diagnosed as fibroadenoma. On retrospective review of the cytology, subtle features such as less cohesive epithelial clusters, intimate association of clusters of stromal cells with epithelial elements, a dominant population of plump-epithelioid naked (myoepithelial) cells, and occasional cells with intranuclear inclusions, were noted. Thus, these lesions can be diagnostically challenging and cannot be conclusively differentiated from either fibroadenoma or tubular adenoma cytologically and the pathologist may only be able to give a differential on FNAC. Recognition of the biphasic nature and the characteristic overall architecture of the tumors in combination with immunohistochemistry are essential to establish the correct diagnosis on biopsy. Although most tumors have a benign clinical course, rare instances of local recurrence, malignant transformation, and distant metastases have been reported. A complete excision with adequate margins would lower the chance of local recurrence.

Adenomyoepithelioma of the breast coexisting with ductal carcinoma in situ: a case report and review of the literature

We herein report a case of adenomyoepithelioma (AME) of the breast with ductal carcinoma in situ (DCIS) involving a 71-year-old Japanese woman. She presented with bloody discharge from the left nipple. Mammography and ultrasonography showed a well-defined polygonal tumor. Fine-needle aspiration cytology of the mass and stamp cytology of the bloody nipple discharge showed malignancy. Mastectomy and a sentinel lymph node biopsy were performed. The final diagnosis was AME of the breast with DCIS. There are no reports of AME of the breast presenting with bloody nipple discharge; upon a diagnosis of AME of the breast with bloody nipple discharge, the possibility of the coexistence of breast cancer should thus be considered when encountering such cases.

Inconclusive or erroneous fine-needle aspirates of breast with adequate and representative material: a cytologic/histologic study

Adequately cellular and representative fine-needle aspirates (FNAs) of breast have a high diagnostic accuracy. There is, however, a recognized category designated as "gray zone" where a definitive diagnosis cannot be reached. We reviewed our experience in this category to identify useful diagnostic parameters. Twenty-four such FNAs with surgical follow-up were retrieved from AUBMC files (2003-2009). Cytology slides were reviewed blindly. All cases were females, 29-73 years. There were three erroneous and 21 inconclusive diagnoses. The majority (15) was invasive adenocarcinomas: two cribriform, four tubular, one lobular, and eight not otherwise specified. The remaining cases were papillary and fibroepithelial tumors (three each), ductal carcinoma in situ, cribriform (two), and one adenomyoepithelioma (AME). Useful diagnostic features included: (1) Biphasic cell population with focal nuclear atypia and intranuclear and cytoplasmic vacuolar inclusions (AME). (2) Complex clusters of epithelial cells with cribriform architecture (cribriform carcinoma). (3) Rigid tubular epithelial structures with abrupt change in diameter, ending in pointed tips with abnormal branching (tubular carcinoma). (4) Cellular stromal fragments (fibroepithelial tumors). (5) Papillary fibrovascular cores, columnar cells, and three-dimensional papillary epithelial fragments (papillary tumors). Myoepithelial cells classically described in benign aspirates were not always a discriminatory factor. The "gray zone" in breast FNA is usually due to overlapping cytologic features of some benign and malignant lesions. Useful distinguishing cytologic features are described.

Indeterminate and erroneous fine-needle aspirates of breast with focus on the 'true gray zone': a review

OBJECTIVE

To review our experience and the literature on inconclusive/erroneous fine-needle aspirates (FNAs) of breast with the focus on the 'true gray zone'. To describe the cytology, differential diagnosis, pitfalls and limitations of common and rare lesions.

STUDY DESIGN

We conducted a literature search focusing on breast FNAs with statistical data of C3 and C4 categories including false-positive and false-negative cases. Similar data from 2003 to 2009 was obtained from our institution.

RESULTS

C3 and C4 categories account for 3-17% of breast FNAs. Contributing factors are technical difficulties, inexperienced pathologists interpreting FNAs of breast and overlap of cytologic features of certain benign and malignant conditions; this last, 'true gray zone' accounts for 2% of cases. Fibroadenoma, proliferative breast lesions, gynecomastia, infiltrating and in situ low-grade adenocarcinomas and tubular, cribriform, lobular and mucinous carcinomas are the most common problematic lesions. Granular cell tumor, adenomyoepithelioma, pregnancy-related lesions, fat necrosis, inflammatory and radiation changes, adenoid cystic carcinoma, spindle-cell lesions and Phyllodes tumor are less common.

CONCLUSION

Inconclusive/erroneous FNAs of breast due to the 'true gray zone' are rare. Most are due to the overlapping cytologic features of some benign and malignant conditions. Practical features that may help arrive at the correct diagnoses are elucidated.