Adenomyoepithelioma of the breast: fine-needle sampling with histologic, immunohistologic, and electron microscopic analysis

The International Academy of Cytology Yokohama System for Reporting Breast Fine-Needle Aspiration Biopsy Cytopathology

The International Academy of Cytology (IAC) gathered together a group of cytopathologists expert in breast cytology who, working with clinicians expert in breast diagnostics and management, have developed the IAC Yokohama System for Reporting Breast Fine-Needle Aspiration Biopsy (FNAB) Cytology. The project was initiated with the first cytopathology group meeting in Yokohama at the 2016 International Congress of Cytology. This IAC Yokohama System defines five categories for reporting breast cytology, each with a clear descriptive term for the category, a definition, a risk of malignancy (ROM) and a suggested management algorithm. The key diagnostic cytopathology features of each of the lesions within each category will be presented more fully in a subsequent atlas. The System emphasizes that the crucial requirements for diagnostic breast FNAB cytology are a high standard for the performance of the FNAB and for the making of direct smears, and well-trained experienced cytopathologists to interpret the material. The performance indicators of breast FNAB, including specificity and sensitivity, negative predictive value, positive predictive value and ROM stated in this article have been derived from the recent literature. The current practice of breast FNAB has evolved with the increasing use of ultrasound guidance and rapid on-site evaluation. Two recent publications have shown a range of ROM for the insufficient/inadequate category of 2.6-4.8%, benign 1.4-2.3%, atypical 13-15.7%, suspicious of malignancy 84.6-97.1%, and malignant 99.0-100%. The management algorithm in the System provides options because there are variations in the management of breast lesions using FNAB and core-needle biopsy in those countries utilizing the "triple test" of clinical, imaging, and FNAB assessment, and also variations in the availability of CNB and imaging in low- and middle-income countries. The System will stimulate further discussion and research, particularly in the cytological diagnostic features of specific lesions within each category and in management recommendations. This will lead to continuing improvements in the care of patients with breast lesions and possible modifications to the IAC Yokohama System.

Adenomyoepithelioma of the breast: a review stressing its propensity for malignant transformation

This review describes the classification, clinical presentation, pathological features and clinical behaviour of adenomyoepithelioma (AME) of the breast. It is based on an extensive review of the literature and study of a collection of cases built up over a 17-year period at the British Columbia Cancer Agency. The diversity of the morphology encountered in both benign and malignant AME is described. The behaviour of malignant AME seems to be related to the grade of the malignant component.

Fine needle biopsy cytology of breast lesions: a review of interpretative difficulties

Screening mammography and greater community awareness of breast carcinoma have led to an increase in fine needle biopsies of the breast. As a consequence, a wide variety of cytologic patterns have been encountered and studied in benign, proliferative, and malignant breast lesions. We review the main reasons for diagnostic difficulties in breast cytology, the situations in which either a false positive or a false negative diagnosis is possible, as well as conditions whose incorrect typing can lead to inappropriate management.

Adenomyoepithelioma of the breast: a cytologic dilemma. Report of a case and review of the literature

Adenomyoepithelioma of the breast is a rare benign tumor made up of epithelial and myoepithelial cells. The cytologic features of this lesion are not well defined. This report describes the cytologic features of a case of adenomyoepthelioma characterized by hypercellularity and the presence of many atypical epithelial cells, leading to the erroneous diagnosis of adenocarcinoma. Review of the cytology literature shows that this condition frequently mimics the cytologic features of a number of benign and malignant breast lesions, thus representing not only an important potential pitfall in the diagnosis of carcinoma but also a differential diagnosis to consider in a variety of breast lesions.

Fine-needle aspiration cytology of benign and malignant adenomyoepithelioma: report of two cases

Cytological features of a malignant spindle-cell variant and a benign tubular variant of adenomyoepithelioma were examined to improve diagnosis of this tumor. Fine-needle aspiration cytology, of both a malignant and a benign case, characterized cellular and cohesive cell clusters composed of epithelial and myoepithelial cells. The smears of the malignant case were rich in spindle-shaped myoepithelial cells, admixed with a few epithelial cells. In about a fourth of the clusters, atypical cells with enlarged hyperchromatic nuclei and prominent nucleoli comprised more than 20% of cells. The smears of the benign case were composed of tubular epithelial cells surrounding one to several layers of myoepithelial cells with clear cytoplasm. Mild atypia was occasionally noticed. A review of the literature showed that a cytological diagnosis of malignancy is not warranted, if nuclear atypia is not generally severe. Focal severe atypia is not definitively indicative of benignity or malignancy.

Fine-needle aspiration cytology of spindle cell lesions of the breast

BACKGROUND

Fine-needle aspiration biopsy (FNA) has been successful in diagnosing epithelial lesions of the breast. Its role in the evaluation of spindle cell and mesenchymal lesions of the breast, which include a variety of benign and malignant conditions, is less clear. This article discusses the cytologic features and differential diagnosis of these lesions, as well as the potential diagnostic pitfalls associated with them.

METHODS

FNAs of the breast, in which a spindle cell or mesenchymal component was a key or dominant feature, were retrieved. Fibroadenomas without cellular stroma and typical lipomas were excluded.

RESULTS

Forty-six aspirates (0.87%) in a series of 5306 breast FNAs contained a significant spindle cell or mesenchymal component. The aspirates were classified into 4 categories: 1) reactive conditions, including 2 diabetic mastopathies, 3 granulation tissue specimens, and 7 granulomatous lesions; 2) benign neoplastic conditions, including 1 mammary hamartoma, 1 dermatofibroma, 1 fibromatosis, 2 granular cell tumors, 2 angiolipomas, and 7 cellular fibroadenomas; 3) low grade malignant neoplastic lesions, including 10 low grade phyllodes tumors; and 4) high grade malignant neoplastic lesions, including 1 metaplastic carcinoma with chondroid stroma, 1 pleomorphic liposarcoma, 2 malignant fibrous histiocytomas, 2 osteosarcomas, and 4 metastatic melanomas. A specific diagnosis was rendered in 38 cases (82.6%). The mammary hamartoma was diagnosed as fibrocystic changes; the dermatofibroma as benign spindle cell lesion, not otherwise specified (NOS); and the primary osteosarcoma as an atypical spindle cell proliferation, NOS. The reactive ductal epithelial cells in one of the granulomatous mastitis specimens, as well as the hyperplastic ductal epithelial cells in one of the phyllodes tumors, were interpreted as atypical ductal proliferation. The marked cytologic atypia displayed by one granular cell tumor was interpreted as low grade adenocarcinoma and the primary liposarcoma as poorly differentiated carcinoma.

CONCLUSIONS

Breast lesions with a significant spindle cell or mesenchymal component are rarely encountered in FNA and constitute a heterogeneous group that may pose a diagnostic dilemma. FNA should be the initial diagnostic procedure for investigating these lesions, as a specific diagnosis was rendered in the majority of cases. Cancer (Cancer Cytopathol)

Adenomyoepithelioma of the breast: report of two cases with prominent cystic changes and intranuclear inclusions

Adenomyoepithelioma is a rare breast tumor. Histologically it may disclose different patterns of growth, and some additional features may result in diagnostic errors. We describe 2 cases of adenomyoepithelioma of the breast initially examined by fine-needle aspiration biopsy (FNAB). Cytologic features included hypercellularity, clusters of epithelial and myoepithelial cells with occasional intranuclear inclusions, prominent apocrine metaplasia, and foam cells. Histologically, both tumors were diagnosed as adenomyepithelioma tubular-variant, with prominent myoepithelial clear cells, apocrine metaplasia, and foci of squamous metaplasia. Immunohistochemically, the tumors showed strong positivity for keratins CAM 5.2, AE1/AE3, and EMA in the epithelial component, while the myoepithelial cells reacted with muscle-specific actin (A14 and HHF35) and S-100 protein. We point out that FNAB in this rare tumor may exhibit a varied spectrum of cells that may result in confusion with other lesions, and we call attention to the presence of intranuclear inclusions. The latter observation in the present cases by cytologic and histologic assessment provides and additional feature to the morphological characteristics of adenomyoepithelioma of the breast.

Fine-needle aspiration cytology of spindle-cell argyrophilic mucin-producing carcinoma of the breast

An unusual breast carcinoma with prominent spindle cells, intracytoplasmic mucin, and argyrophilia in an 82-yr-old woman was sampled preoperatively by fine-needle aspiration (FNA). The smears contained highly cellular sheets and fragments of uniform spindle cells with abundant vacuolated cytoplasm. The cells were mucicarmine positive and contained many cytoplasmic argyrophilic granules. The findings were confirmed by histologic examination of the excised tumor, which was also studied with a panel of immunohistochemical stains. A review of the literature indicated that spindle-cell argyrophilic mucin-producing carcinoma (SCAMPC) of the breast is a very rare neoplasm presenting primarily in elderly patients. The FNA cytologic features seem to be unique and should allow distinction from other primary breast lesions.

Adenomyoepithelioma of the Breast: A Case Reprot and a Review of Literature

A 74-year-old woman complained of a small nodule in the outer lower quadrant of her left breast. On physical examination, a 0.9 x 0.8 cm, round-shaped and firmly elastic nodule was palpated. Excisional biopsy was performed. Histologically, the tumor was separated into, with a bicellular pattern, containing both numerous glandular structures and numerous spindle-shaped cells. Immunohistochemical staining for EMA and cytokeratin showed strongly positive immunoreactivity for epithelial cells. Staining for &aipha;-SMA showed strongly positive immunoreactivity for myoepithelial components. Staining for keratin and S-100 protein showed weakly positive immunoreactivity for myoepithelial cells. Microscopically, the tumor was diagnosed as adenomyoepithelioma of the breast. Immunohistochemical examination is needed to distinguish epithelial cell proliferation from myoepithelial cell proliferation. Immunohistochemical examination using antibodies against EMA, alpha-SMA, Keratin, cytokeratin and S-100 protein, is indispensable.

Adenomyoepithelioma of the breast: fine-needle aspiration biopsy and histologic findings

Adenomyoepithelioma is an uncommon tumor of the breast which clinically presents as a discrete nodule and histologically is composed of lumenal spaces lined by a mixture of epithelial and myoepithelial cells. It has a spectrum of histologic appearances which are gradually gaining wider recognition. There are, however, only a few descriptions of the fine-needle aspiration biopsy (FNAB) findings in adenomyoepithelioma. We report the FNAB and histologic features of a mammary adenomyoepithelioma which contained a prominent epithelial component including a focus of marked epithelial atypia. This expands the spectrum of FNAB findings which have been reported in adenomyoepithelioma.

Fine-needle aspiration cytology of mammary adenomyoepithelioma: report of a case with intranuclear cytoplasmic inclusions

Adenomyoepithelioma of the breast is an uncommon lesion which may recur and rarely metastasizes. We report the fine-needle aspiration (FNA) findings in one case of mammary adenomyoepithelioma in which this tumor's unusual cytomorphology led to a cytologic diagnosis of malignancy, possible metastatic to the breast. Large, atypical, polygonal cells, some with intranuclear cytoplasmic inclusions, were most worrisome cytologically, but corresponded in the biopsied specimen to cells immunohistochemically documented to be of myoepithelial origin. Nests of epithelium and myoepithelial cells sometimes embedded in fibrous, stromal fragments were suggestive of an infiltrating pattern. Recognition of such unusual features in breast FNA is most important since definitive therapy may follow an FNA diagnosis of carcinoma in some clinical settings. In cases with unusual morphology, surgical biopsy should be recommended to clarify the nature of the lesion.