Tubular adenosis of the breast. A distinctive benign lesion mimicking invasive carcinoma

Benign breast lesions that mimic malignancy

Many benign and reactive lesions of the breast show morphological overlap with malignant lesions. These benign mimics of malignancy often present diagnostic challenges to even the most experienced pathologists. This review focuses on several benign lesions of the breast that mimic malignant entities. For each of these lesions, we describe the key morphological and immunohistochemical features, potential diagnostic pitfalls, and our approach to arriving at the correct diagnosis.

Diagnostic role of immunohistochemistry in the evaluation of breast pathology specimens

CONTEXT

Immunohistochemistry plays a vital role in the evaluation of breast pathology specimens.

OBJECTIVE

To discuss the role of myoepithelial cell markers in the evaluation of various breast lesions. Other markers, such as E-cadherin and those used to differentiate mammary carcinoma from metastatic tumors to the breast, and markers used in the differential diagnosis of Paget disease, are also discussed.

DATA SOURCES

Data were obtained from review of the pertinent peer-reviewed literature.

CONCLUSIONS

Myoepithelial cell markers vary in their sensitivity and specificity, and one should be aware of the potential pitfalls in interpretation. Using panels of 2 or more myoepithelial cell markers is always recommended, either singly or in cocktail forms. Although negative E-cadherin staining supports the diagnosis of lobular origin, positive staining does not rule it out. Immunohistochemistry can be helpful in differentiating Paget disease from its mimics. Although metastatic tumors to the breast are rare, a triple-negative immunophenotype and absence of an in situ component should be a "red flag" for such possibility, especially in patients with clinical history of an extramammary malignancy.

Use of fine-needle aspiration in the evaluation of breast lumps

Background. A study was designed to see the role of fine needle aspiration cytology (FNAC) in palpable breast lumps. Materials and Methods. Four hundred and twenty five (425) patients came to the Department of Pathology King Edward Medical University, Lahore in four years for FNAC of their palpable breast masses from June 2006 to June 2010. FNAC diagnosis was compared with histological diagnosis to see the accuracy of fine needle aspiration cytology for neoplastic lesions. Results. There were 271/425 benign, 120/425 malignant, and 32/425 suspicious smears. Inadequate samples were repeated twice or thrice, and the degree of success was improved with consecutive repeating approaches. The frequency of inadequacy declined from 86 to 18, and 2 for first, second and third attempts, respectively. The number of repeats increased the diagnostic accuracy of aspirates which is statistically significant (P = .000). Invasive ductal carcinoma was the most commonly reported lesion with maximum incidence in the 4th, 5th, and 6th decades followed by invasive lobular carcinoma and other malignant lesions. The sensitivity, specificity, accuracy, negative predictive value, and the positive predictive value of FNAC was 98%, 100%, 98%, 100%, and 97%, respectively. Conclusion. FNAC serves as a rapid, economical, and reliable tool for the diagnosis of palpable breast lesions because the cytopathological examination of these lesions before operation or treatment serves as an important diagnostic modality.

[Immunohistochemistry in breast pathology: differential diagnosis of epithelial breast lesions]

Proliferative epithelial breast lesions include a wide variety of benign hyperplastic and noninvasive neoplastic lesions, as well as invasive carcinomas. Mammographically these lesions may show microcalcifications, architectural distortions or mass lesions. The task of the pathologist begins with a preoperative diagnosis by means of minimally invasive biopsy. His diagnosis forms the basis for not only the radiological-pathological correlation diagnosis, but also for the management of benign proliferative breast disease lesions, as well as therapeutic decisions in the case of malignant lesions.In daily practice, immunohistochemistry is the method of choice for clarifying difficult cases. The aim of this chapter is to describe the relevant markers in breast pathology and to provide an algorithmic approach to different proliferative breast disease lesions.

Molecular and morphological analysis of adenoid cystic carcinoma of the breast with synchronous tubular adenosis

Adenoid cystic carcinoma (ACC) of the breast is a rare tumour. Its recognition as a special type of breast carcinoma is very important because its prognosis is better than the not-otherwise-specified invasive ductal carcinoma and its treatment may not include axillary dissection. Tubular adenosis (TA) is a very rare condition of the breast that is histologically benign; however, it has been described in association with invasive ductal carcinoma. There are scant data regarding the molecular genomic alterations in ACC of the breast and no data has been presented on TA. Herein, we provide a morphological characterisation of TA arising synchronically with ACC in the breast. To characterise these lesions, we performed ultrastructural analysis, three-dimensional reconstruction and molecular analysis using immunohistochemistry and comparative genomic hybridisation. The copy number alterations found in ACC were restricted to small deletions on 16p and 17q only, whereas the TA harboured gains on 1q, 5p, 8q, 10q, 11p and 11q and losses on 1p, 10q, 11q, 12q, 14q, 15q and 16q. These molecular data highlight the genomic instability of TA, a benign florid proliferation intermingled with ACC, and do not provide evidence of molecular evolution from TA to ACC.

Benign breast diseases: classification, diagnosis, and management

Benign breast diseases constitute a heterogeneous group of lesions including developmental abnormalities, inflammatory lesions, epithelial and stromal proliferations, and neoplasms. In this review, common benign lesions are summarized and their relationship to the development of subsequent breast cancer is emphasized.

Intraoperative assessment of the breast: guidelines and potential pitfalls

CONTEXT

Intraoperative evaluation of breast tissue has changed as newer imaging techniques and surgical approaches to the treatment of breast cancer have placed the pathologist in a pivotal role in the management of this disease. Assessment of the index lesion and surgical margins are but two of the many tasks we face when the specimen arrives in the surgical pathology laboratory. We are also called on to correlate changes in the mammogram with the gross pathology, particularly in those cases in which the lesion is nonpalpable. More recently, pathologists have been asked to analyze 1 or more sentinel lymph nodes at the time of frozen section to look for metastatic disease. This review discusses many of these issues and also provides a simplified approach to the differential diagnosis of a variety of breast lesions one may encounter intraoperatively.

OBJECTIVE

To provide guidelines for and address potential pitfalls in the intraoperative management of the breast.

DATA SOURCES

Author's experience and pertinent literature.

CONCLUSIONS

Careful assessment of the gross specimen coupled with prudent utilization of frozen sections is pivotal to reducing intraoperative error rates and preventing needless anxiety for the patient.

Immunostaining of Type IV Collagen and Smooth Muscle Actin as an Aid in the Diagnosis of Breast Lesions

The immunohistochemical staining patterns of type IV collagen (TIVC) and smooth muscle actin (SMA) were studied in benign and malignant breast lesions in order to assess their usefulness in the differential diagnosis of difficult lesions. Eighty-six in situ breast carcinomas (8 with microinvasion; 1 diagnosed after immunostaining) and 58 invasive carcinomas, with associated benign lesions including 87 nonproliferative fibrocystic changes, 19 sclerosing adenosis, 17 atypical hyperplasias, 7 benign papillary proliferations, 6 radial scars, and 105 normal mammary tissue, were studied. TIVC and SMA were concomitantly positive throughout in 94% of benign tissues, in 16% of in situ carcinomas, but in none of the invasive carcinomas. Conversely, both markers were negative in 66% of invasive carcinomas, but in none of the benign breast tissue and none of the in situ carcinomas. In 6% of the benign tissues, in 21% of in situ carcinomas, and in 34% of invasive carcinomas only one of the markers was positive. In the remaining 63% of the in situ carcinomas there were discontinuities of the staining of both markers. It is therefore suggested that a diagnosis of invasive malignancy can be confirmed when both markers are negative, and ruled out when both markers are positive. This is particularly useful, in our experience, in the identification of small foci of invasion. The stains are useful when used in parallel, whereas they may be misleading when used singly. The staining pattern is not useful in the differential diagnosis of atypical hyperplasia and in situ carcinoma.