Fibroepithelial Lesions With Cellular Stroma on Breast Core Needle Biopsy

Update on percutaneous needle biopsy of nonmalignant breast lesions

Certain nonmalignant lesions encountered on percutaneous breast biopsies pose dilemmas with regard to the most appropriate clinical management subsequent to needle biopsy (ie, surgical excision vs. follow-up). These lesions include columnar cell lesions, atypical ductal hyperplasia, lobular neoplasia, papillary lesions, radial scars, fibroepithelial lesions, and mucocele-like lesions. As minimally invasive diagnostic procedures are now standard it is more important than ever to be aware of the limitations of percutaneous biopsy, particularly with regard to apparently benign lesions because of the risk that the radiologically detected lesion may harbor malignant disease not represented in the biopsy specimen. This underscores the importance of radiologic-pathologic correlation. Increasingly, radiologists are adopting vacuum-assisted devices using larger gauge needles. The changing practices among radiologists are reflected in recent studies which have enriched the literature. In addition, magnetic resonance imaging is being used more frequently in breast imaging, resulting in pathologists more often encountering benign biopsies with uncertain imaging correlation. These changes prompted evaluation of the recent literature and its possible effect on management concerns. This review focuses on management issues following the diagnosis of nonmalignant lesions diagnosed on percutaneous breast biopsy and highlights imaging terms commonly used in breast radiology reports to facilitate accurate radiologic-pathologic correlation.

Update on Fibroepithelial Lesions of the Breast

This article focuses on current issues relating to fibroepithelial lesions, predominantly those with cellular stroma, and covers key pathologic features, differential diagnosis, and pitfalls. Phyllodes tumors are emphasized, including the histologic categorization and prognostic features of these lesions. The management of fibroepithelial lesions on needle core biopsy is reviewed.

Recurrent challenges in the evaluation of fibroepithelial lesions

CONTEXT

The morphologic spectrum of mammary fibroepithelial lesions ranges from fibroadenoma, a common benign neoplasm, to phyllodes tumor, an uncommon lesion that can sometimes recur and metastasize.

OBJECTIVE

To focus on problems encountered in the diagnostic evaluation of fibroepithelial tumors, highlighting the diagnostically relevant morphologic features and providing an update on the immunohistochemical profile and genetic alterations of these rare neoplasms.

DATA SOURCES

A PubMed search of the English-language literature identified published reports on fibroepithelial lesions, with a special focus on phyllodes tumor. The results and conclusions of these studies form the basis of this review.

CONCLUSIONS

The distinction between fibroadenoma and phyllodes tumor is usually not problematic, especially in excision specimens. In some cases, however, the diagnostic evaluation of fibroepithelial lesions can be challenging, especially if only limited material is available. Morphologic predictors of local recurrence of phyllodes tumor include cellularity and cytologic atypia, mitotic activity, positive margins, infiltrative borders, fibroproliferative satellite nodules, and past history of fibroadenoma. Predictors of distant metastasis include size, tumor necrosis, and stromal overgrowth. None of these parameters, however, constitutes a definite marker of malignancy. Presently, molecular and immunohistochemical techniques play a limited role in the diagnosis of fibroepithelial lesions.

False-negative diagnoses at stereotactic vacuum-assisted needle breast biopsy: long-term follow-up of 1,280 lesions and review of the literature

OBJECTIVE

The purpose of this study was to determine retrospectively the frequency and causes of false-negative diagnoses of lesions evaluated with percutaneous stereotactic biopsy performed with vacuum-assisted probes with the patient prone on a biopsy table.

MATERIALS AND METHODS

The records of 1,152 women (median age, 55 years; range, 31-94 years) with 1,280 lesions consecutively biopsied with 14-gauge (n = 159) or 11-gauge (n = 1,121) vacuum probes were reviewed retrospectively. The histologic diagnoses were malignant (n = 489), high-risk (n = 117), and benign (n = 674) lesions. Benign lesions were evaluated with repeated biopsy (n = 46) or mammographic follow-up for 24 months or longer (n = 506) or less than 24 months (n = 57). In 65 cases (10% of all benign lesions), follow-up was not performed. Fisher's exact tests were used to correlate patient, mammographic, and biopsy variables with false-negative diagnoses.

RESULTS

Of 508 lesions with a final diagnosis of malignancy, the initial needle biopsy diagnosis was malignant (n = 489), high-risk (n = 14), or benign (n = 5) lesion. The five false-negative diagnoses were related to gauge of the biopsy probe and specimen radiographic findings regarding calcifications but were not related to lesion type. False-negative diagnoses were made in 4.4% (three of 68) of cases in which 14-gauge vacuum biopsy was performed and in 0.45% (two of 440) of cases in which 11-gauge vacuum biopsy was performed (p = 0.019). False-negative diagnoses were made in 25% (one of four) of cases in which specimen radiographs showed no calcifications and 0.67% (two of 300) of cases in which they did show calcifications (p = 0.0390). False-negative diagnoses were made in 1.2% (three of 248) of cases of calcification lesions and 0.8% (two of 260) of cases of mass lesions (p = 0.679).

CONCLUSION

False-negative findings at stereotactic biopsy were least common with 11-gauge probes and were similar in frequency for calcifications and masses.

Predictive value of needle core biopsy diagnoses of lesions of uncertain malignant potential (B3) in abnormalities detected by mammographic screening

AIMS

Breast needle core biopsy (NCB) is now a commonplace diagnostic procedure in breast cancer screening, providing accurate diagnoses of both benign and malignant lesions. However, NCB may result in the borderline diagnoses of lesion of uncertain malignant potential (B3) or suspicious of malignancy (B4). The aim was to study a large series of B3 cases from population-based screening subjects in order to evaluate positive predictive values (PPVs) for malignancy.

METHODS AND RESULTS

The results of 523 NCBs of women screened over a 7-year period (1999-2006) in the East Midlands region, UK, with a B3 diagnosis who underwent surgical excision, were reviewed and compared with the final excision histology. Five percent of NCBs were reported as B3. The most frequent histological subtypes were atypical intraductal epithelial proliferation (AIDEP) and radial scar/complex sclerosing lesion (RS/CSL). Final excision histology was benign in 417 (80%) and malignant in 106 (20%) subjects (60 ductal carcinoma in situ and 46 invasive carcinoma). Lesion-specific PPVs were as follows: AIDEP 32%; lobular neoplasia (LN) 30%; RS/CSL with AIDEP or LN 24%; RS/CSL without atypia 9%; papillary lesion with AIDEP or LN 36%; and papillary lesion without atypia 4%. Five of the 32 fibroepithelial lesions with cellular stroma were phyllodes tumours (four benign and one borderline). None of the five mucinous lesions on NCB was malignant.

CONCLUSIONS

Our results show that approximately one-fifth of NCB of screen-detected breast lesions classified as B3 are malignant on excision, and the likelihood of malignancy varies substantially between different histological subtypes.

“Missed” Diagnoses of Phyllodes Tumor on Breast Biopsy: Pathologic Clues to Its Recognition

Fibroadenoma and phyllodes tumors of the breast exhibit a continuum of pathologic features. We examined phyllodes tumors initially called fibroadenoma for features that may accurately classify the tumor as phyllodes tumor on the first biopsy specimen. The phyllodes tumors initially called fibroadenoma for features that may accurately classify the tumor as phyllodes tumors on the first biopsy specimen are examined. Fifteen patients with phyllodes tumors were studied, initially called FA or another term short of PT. These tumors were compared with 16 true fibroadenomas, all with needle-core biopsy followed by excision. Resected phyllodes tumors were larger on average than fibroadenoma, 6.8 cm (range = 1.7-16.2 cm) versus 2.6 cm (range = 1.0-4.8 cm). In needle-core biopsy cases, sampling was limited, even in large breast masses. p53 and cleaved caspase-3 were noncontributory. Ki-67 showed higher proliferation indices in phyllodes tumors versus fibroadenoma (4.8% vs 0.6%). Features suggesting phyllodes tumors include tissue fragmentation, increased stromal cellularity especially around glands, stromal overgrowth, and increased mitoses. Increased sampling of a large tumor will likely yield more correct diagnoses.

Recent developments in the histological diagnosis of spindle cell carcinoma, fibromatosis and phyllodes tumour of the breast

This article reviews recent advances in the diagnosis of these three unusual tumours of the breast. Spindle cell carcinoma needs to be considered in the differential diagnosis of many mammary spindle cell lesions: it is important to be aware of the wide range of appearances, including the recently described fibromatosis-like variant. Immunohistochemistry using a broad panel of cytokeratin antibodies is needed to exclude spindle cell carcinoma; there is frequent expression of basal cytokeratins and p63. CD34 is often expressed by the stroma of phyllodes tumours, but does not appear to be expressed by spindle cell carcinoma or fibromatosis. Nuclear beta-catenin is found in about 80% of fibromatoses, but can also be seen in spindle cell carcinomas and phyllodes tumours. Two recent studies have described features useful in the distinction of phyllodes tumour and fibroadenoma on core biopsy, including increased cellularity, mitoses and overgrowth of the stroma, adipose tissue in the stroma and fragmentation of the biopsy specimen. Periductal stromal tumour is a recently described biphasic tumour composed of spindle cells around open tubules or ducts (but no leaf-like architecture) with frequent CD34 expression. The overlap of morphology with phyllodes tumour suggests that it may be best regarded as a variant of phyllodes tumour.

Breast Screening in Singapore: Implications for Pathology

The aim of this review is to discuss the impact of breast screening on pathology. The advent of the national mammographic screening programme in Singapore has led to changes in the manner in which breast specimens are handled in the pathology laboratory, an increased detection of borderline lesions which pose diagnostic challenges, the occurrence of specific issues regarding core biopsies, and the need for awareness of histologic artefacts associated with preoperative needling procedures. There are also economic and workload implications, in addition to the essential requirement for quality assurance and educational programmes to maintain high professional standards. A multidisciplinary approach and commitment to continual professional upgrading are key to surmounting the pathologic challenges brought about by breast screening. Key words: Borderline lesions, Quality assurance, Radiologic calcifications, Workload

Histological features useful in the distinction of phyllodes tumour and fibroadenoma on needle core biopsy of the breast

AIM

To identify features useful in distinguishing phyllodes tumours from fibroadenomas on core biopsy.

METHODS AND RESULTS

Starting from the diagnosis made on the surgical specimen, 12 features in the previous core biopsy specimens were analysed. Thirty-six phyllodes tumours had 44 previous core biopsy specimens, which were reported as fibroadenoma in 11 and spindle cell lesion of uncertain nature in one, and included phyllodes tumour in the differential diagnosis in 32. The lesions with a core diagnosis of fibroadenoma were excised largely because they were growing or exceeded 30 mm; review of the corresponding surgical specimen showed heterogeneous stromal cellularity. Thirty-eight fibroadenomas had previous core biopsy specimens reported as fibroadenoma in 37, and one of which included phyllodes tumour in the differential diagnosis. The following four features were significantly more common in cores from phyllodes tumours and had a kappa statistic of > 0.6 in a reproducibility study: stromal cellularity increased in at least 50% compared with typical fibroadenoma, stromal overgrowth (x10 field with no epithelium), fragmentation and adipose tissue within stroma.

CONCLUSIONS

This study describes features useful in the diagnosis of phyllodes tumour on core biopsy. Some core biopsy specimens from phyllodes tumours show features of fibroadenoma on core biopsy because of tumour heterogeneity.

Unusual Breast Cancers: Useful Clues to Expanding the Differential Diagnosis

Invasive ductal carcinoma and ductal carcinoma in situ account for about 85% of breast cancers. Unusual breast neoplasms may be broadly divided into invasive lobular carcinoma, well-differentiated subtypes of invasive ductal carcinoma, cancers of stromal origin, and metastatic neoplasms. Clues are often present in imaging characteristics, patient demographics, and/or clinical features that may suggest that the finding is not the usual type of breast cancer. Some rare malignancies also provide specific clues to their diagnosis. This review provides an overview of unusual and a few rare malignant breast neoplasms, highlighting particular or specific clinical or imaging findings that will enable residents to expand their differential diagnosis of breast lesions beyond invasive ductal carcinoma.

Breast core biopsy reporting categories—An internal validation in a series of 3054 consecutive lesions

We reviewed 3226 consecutive core biopsies (CBs) of 3054 mammographically detected breast lesions performed at our Centre from November 1993 to June 2003. CB diagnoses, classified according to the Non-operative Diagnosis Subgroup of the British National Health Service Breast Cancer Screening Programme (NHSBSP), were B5 (37.1%), B4 (0.5%), B3 (7.6%), B2 (50.9%) and B1 (3.9%). It was necessary to repeat the procedure in 172 cases (5.3%). The values for absolute sensitivity and specificity are 90.8% and 83.8%, respectively. The positive predictive value for categories B4 and B5 is 100%, with no false-positives. The positive predictive value for category B3 is 16.3%. The negative predictive value for B2 category is 97.2%, with a false-negative rate of 3.5%. In conclusion, this system of analysis has enabled us to confirm that our CB results surpass the minimum recommended standards proposed by the NHSBSP.