Radial scar/complex sclerosing lesion--a problem in the diagnostic work-up of screen-detected breast lesions

Overcoming Pitfalls in Breast Fine-Needle Aspiration Cytology: A Practical Review

BACKGROUND

Fine-needle aspiration cytology (FNAC) is a cornerstone technique for the initial assessment of breast lesions, offering a rapid and minimally invasive option for cytological evaluation. While FNACs can forego the need for core needle biopsies (CNBs), variations in technique, subjective interpretation, and intrinsic limitations present diagnostic challenges. The International Academy of Cytology (IAC) established the Yokohama system and is developing the WHO Reporting System for Breast Cytopathology jointly with IARC, to standardize diagnostic criteria, aiming to enhance diagnostic precision and consistency. Due to the preference for CNBs, expertise in breast FNAC is low in the developed world.

SUMMARY

This review assesses common pitfalls in breast cytopathology. These common and uncommon entities may easily lead to false-negative or false-positive diagnoses, due to morphological overlap or misleading clinical and radiological contexts. For instance, pauci-cellular lesions, such as lobular carcinomas, often lead to false-negative diagnoses, whereas complex sclerosing lesions, fibroadenomas, and papillary lesions may show concerning features, resulting in a false positive. The same is true for some benign inflammatory pathologies, such as steatonecrosis, and uncommon lesions, such as collagenous spherulosis. Ductal carcinoma in situ can lead to both false-negative and false-positive diagnoses, and high-grade lesions are impossible to tell apart from invasive carcinomas. These are discussed in detail. Procedural and preanalytical conditions, and the role of ancillary testing, are also briefly addressed.

KEY MESSAGES

Breast FNAB is a powerful diagnostic technique, fast and minimally invasive. Even in contexts which lack expertise, this technique can be successfully adopted with a cautious approach and as long as pitfalls are kept in mind, benefiting patients and healthcare systems.

Real-World Diagnostic Accuracy of the On-Site Cytopathology Advance Report (OSCAR) Procedure Performed in a Multidisciplinary One-Stop Breast Clinic

Fine-needle aspiration (FNA) cytology has been widely used for the diagnosis of breast cancer lesions with the objective of differentiating benign from malignant masses. However, the occurrence of unsatisfactory samples and false-negative rates remains a matter of concern. Major improvements have been made thanks to the implementation of rapid on-site evaluation (ROSE) in multidisciplinary and integrated medical settings such as one-stop clinics (OSCs). In these settings, clinical and radiological examinations are combined with a morphological study performed by interventional pathologists. The aim of our study was to assess the diagnostic accuracy of the on-site cytopathology advance report (OSCAR) procedure on breast FNA cytologic samples in our breast OSC during the first three years (April 2004 till March 2007) of its implementation. To this goal, we retrospectively analyzed a series of 1820 breast masses (1740 patients) radiologically classified according to the American College of Radiology (ACR) BI-RADS lexicon (67.6% being either BI-RADS 4 or 5), sampled by FNA and immediately diagnosed by cytomorphology. The clinicoradiological, cytomorphological, and histological characteristics of all consecutive patients were retrieved from the hospital computerized medical records prospectively registered in the central information system. Histopathological analysis and ultrasound (US) follow-up (FU) were the reference diagnostic tests of the study design. In brief, we carried out either a histopathological verification or an 18-month US evaluation when a benign cytology was concordant with the components of the triple test. Overall, histology was available for 1138 masses, whereas 491 masses were analyzed at the 18-month US-FU. FNA specimens were morphologically nondiagnostic in 3.1%, false negatives were observed in 1.5%, and there was only one false positive (0.06%). The breast cancer prevalence was 62%. Diagnostic accuracy measures of the OSCAR procedure with their 95% confidence intervals (95% CI) were the following: sensitivity (Se) = 97.4% (96.19-98.31); specificity (Sp) = 94.98% (92.94-96.56); positive predictive value (PPV) = 96.80% (95.48-97.81); negative predictive value (NPV) = 95.91% (94.02-97.33); positive likelihood ratio (LR+) = 19.39 (13.75-27.32); negative predictive ratio (LR-) = 0.03 (0.02-0.04), and; accuracy = 96.45% (95.42-97.31). The respective positive likelihood ratio (LR+) for each of the four categories of cytopathological diagnoses (with their 95% CI) which are malignant, suspicious, benign, and nondiagnostic were 540 (76-3827); 2.69 (1.8-3.96); 0.03 (0.02-0.04); and 0.37 (0.2-0.66), respectively. In conclusion, our study demonstrates that the OSCAR procedure is a highly reliable diagnostic approach and a perfect test to select patients requiring core-needle biopsy (CNB) when performed by interventional cytopathologists in a multidisciplinary and integrated OSC setting. Besides drastically limiting the rate of nondiagnostic specimens and diagnostic turn-around time, OSCAR is an efficient and powerful first-line diagnostic approach for patient-centered care.

Infiltrating Epitheliosis of the Breast: Fine Needle Aspiration Cytology

Epitheliosis (or usual duct hyperplasia) is a proliferation of epithelial and myoepithelial cells located within enlarged acini and small ducts, which is characterized by irregular and peripheral fenestration. Infiltrating epitheliosis (IE) is a specific lesion, characterized by classical epitheliosis flowing out into the adjacent stroma. The stroma is desmoplastic and shows keloid appearance with irregular elastosis. IE can mimic malignancy both on radiological and histological grounds. The aim of the present study is to describe the fine needle aspiration cytological features of 6 consecutive cases of IE, with histological correlation. IE cases presenting as screen detected lesions and preoperatively diagnosed on fine needle aspiration cytology (FNAC) were reviewed. All patients had radiologically breast lesions suspicious for malignancy that underwent FNAC followed by surgical resection. The FNAC smears presented some features that could lead to a misdiagnosis of malignancy, such as bloody background, high cellularity, and stromal fragments containing epithelial cells. Nevertheless, malignancy was excluded, due to the absence of atypia and the presence of myoepithelial cells in the cell clusters. IE presents a special FNAC pattern that can be misinterpreted as malignancy. Therefore, knowledge is necessary to avoid patient overtreatment.

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.

The International Academy of Cytology Yokohama System for Reporting Breast Fine Needle Aspiration Biopsy Cytopathology: A Single Institutional Retrospective Study of the Application of the System Categories and the Impact of Rapid Onsite Evaluation

OBJECTIVES

To review the performance and utility of the International Academy of Cytology (IAC) Yokohama System for Reporting Breast Fine Needle Aspiration Biopsy (FNAB) Cytology five category stratification and evaluate the impact of rapid onsite evaluation (ROSE).

METHOD

A retrospective analysis of breast FNAB cytology cases with matched histopathological results at a single institution over a 32 months period using a structured reporting system with 5 diagnostic categories ("inadequate/insufficient," "benign," "atypical," "suspicious of malignancy" and "malignant") closely paralleling the proposed IAC System.

RESULTS

Of 2,696 breast FNAB cases, there were 579 with matched histopathology and 456 of these had ROSE. ROSE decreased the number in the "insufficient" category (17.1% without ROSE to 4.0% with ROSE) and increased the number in the "malignant" (17.9 to 39.0%) with a lesser impact on the "atypical," "benign" and "suspicious of malignancy" categories. The performance data showed a positive predictive value of 96.4%, negative predictive value of 97.6%, and a risk of malignancy of a FNAB categorized as "insufficient" to be 2.6%, "benign" 1.7%, "atypical" 15.7%, "suspicious of malignancy" 84.6%, and "malignant" 99.5%.

CONCLUSION

Breast FNAB is an accurate test enabling effective diagnosis of breast lesions. ROSE improved the performance by decreasing the proportion of "insufficient" and "atypical" and increasing the "suspicious of malignancy" and "malignant" diagnoses and enabling immediate triage for further biopsy where necessary.

Breast cancer risk associated with the diagnosis of a microhistological radial scar (RS): retrospective analysis in 10 years of experience

PURPOSE

To retrospectively assess the risk of breast cancer associated with the radial scar (RS) microhistological diagnosis, also taking into consideration the percutaneous biopsy devices used, as well as the different performances of the mammographic systems (analogical, digital and tomosynthesis) in the radiological diagnosis of RS.

MATERIALS AND METHODS

Between March 2002 and November 2011, 80 RSs were identified using the analogical, digital and tomosynthesis mammographic systems. Based on the microhistological examination, the patients were divided into three groups [RS without hyperplasic-proliferative lesions (HPL); RS with HPL; RS with cancer] and we assessed the risk of cancer associated with RS in the first and second group. We evaluated the mammographic features and the BI-RADS categories assigned to RSs, the biopsy devices used and the differences between the pathological examination and the microhistological diagnosis (p < 0.05).

RESULTS

Based on the microhistological examination, 51/80 patients were included in the first group (9 of them not subjected to surgery), 25/80 in the second group and 4/80 in the third one. At the final histological examination, there were 7/42 (16.7%) cancers in the first group and 8/25 (32%) in the second group. The largest number of microhistological underestimation occurred in the patients who were subjected to core biopsy (15 cases) (p < 0.05). Tomosynthesis improved (p < 0.05) the identification of the RS.

CONCLUSIONS

22.3% of the RSs was associated with cancer. Given that at microhistological examination 16.7% of the RS without HPL was cancer at pathology, the surgical excision is preferred. Tomosynthesis was useful to detect parenchymal distortions.

Dual effects of exercise in dysferlinopathy

Dysferlinopathy refers to a group of autosomal recessive muscular dystrophies due to mutations in the dysferlin gene causing deficiency of a membrane-bound protein crucially involved in plasma membrane repair. The condition is characterized by marked clinical heterogeneity, the different phenotypes/modes of presentation being unrelated to the genotype. For unknown reasons, patients are often remarkably active before the onset of symptoms. Dysferlin deficiency-related persistence of mechanically induced sarcolemma disruptions causes myofiber damage and necrosis. We postulate that limited myodamage may initially remain hidden with well-preserved resistance to physical strains. By subjecting dysferlin-deficient B6.A/J-Dysf(prmd) mice to long-term swimming exercise, we observed that concentric/isometric strain improved muscle strength and alleviated muscular dystrophy by limiting the accumulation of membrane lesions. By contrast, eccentric strain induced by long-term running in a wheel worsened the dystrophic process. Myofiber damage induced by eccentric strain increased with age, reflecting the accumulation of non-necrotic membrane lesions up to a critical threshold. This phenomenon was modulated by daily spontaneous activity. Transposed to humans, our results may suggest that the past activity profile shapes the clinical phenotype of the myopathy and that patients with dysferlinopathy should likely benefit from concentric exercise-based physiotherapy.

The clinical effectiveness of fine needle aspiration biopsy in patients with palpable breast lesions seen at the University College Hospital, Ibadan, Nigeria: A 10-year retrospective study

Background:

Although open surgical biopsy is the ‘gold standard’ for diagnosis of palpable breast lesions, in recent years two types of minimally invasive breast biopsy techniques, core needle biopsy and fine needle aspiration biopsy (FNAB), have become established for the diagnostic evaluation of palpable breast lesions.

Aims:

This study was undertaken to evaluate the clinical effectiveness of FNAB as a first line diagnostic procedure in the management of patients with breast lumps in University College Hospital (UCH), Ibadan, using the suggested thresholds for cytology performance as recommended by the United Kingdom National Health Services Breast Screening Programme (NHSBSP).

Settings and Design:

A 10-year retrospective cohort study carried out in the Pathology Department of UCH.

Materials and Methods:

All FNAB and histologically diagnosed cases of breast lesions in the pathology department between January 1996 and December 2005 were reviewed. The cytological diagnoses were then categorized into one of five diagnostic categories in accordance with the recommendations of the NHSBSP.

Results:

The positive predictive value for malignancy was 99.3% with a complete sensitivity of 97.7% and specificity (full) of 94.2%.

Conclusions:

The high quality assurance measures obtained in this study affirms FNAB as a clinically effective diagnostic procedure for breast lesions.

Fine-needle aspiration cytology of the breast

Fine-needle aspiration cytology (FNAC) is an established, highly accurate, and cost-effective method for diagnosing lesions in different organs, including the breast. The method is minimally invasive without unwanted side effects. FNAC forms part of the triple assessment of breast lesions. Despite some shortcomings of the reporting categories, FNAC as part of the triple assessment has proved its value in describing the findings most accurately. The diagnostic impact depends on experience of the operator, quality of preparation, and diagnostic skills of the cytopathologist. The highest accuracy is achieved at centers with a multidisciplinary approach. FNAC is often palpation guided from palpable breast masses, whereas ultrasonography guidance is more widely used on nonpalpable lesions. Inadequate sampling with FNAC is particularly seen in collagenous lesions and in submitted specimens sampled by physicians lacking experience with the FNAC procedure. A diagnostic biopsy is recommended when FNAC provides scant material. FNAC is considered to be a safe method for screening purposes, although moderately less sensitive than core needle biopsy. FNAC is most accurate when experienced cytopathologists are available to assess the adequacy of the aspirated material and advise on additional aspirations for ancillary tests when needed.

Assessment of 1183 screen-detected, category 3B, circumscribed masses by cytology and core biopsy with long-term follow up data

Discrete masses are commonly detected during mammographic screening and most such lesions are benign. For lesions without pathognomonically benign imaging features that are still regarded likely to be non-malignant (Tabar grade 3) reliable biopsy results would be a clinically useful alternative to mammographic surveillance. Appropriate institutional guidelines for ethical research were followed. Between Jan 1996--Dec 2005 grade 3B discrete masses detected in the setting of a large, population based, breast cancer screening programme are included. Patient demographics, fine needle aspiration biopsy (FNAB), core and surgical biopsy results are tabulated. The final pathology of excised lesions was obtained. Information regarding interval cancers was obtained from the State Cancer Registry records and also through long term follow-up of clients in subsequent rounds of screening. A total of 1183 lesions, mean diameter of 13.3 mm (+/-8.3 mm) and mean client age of 55.1 years (+/-8.8 years) are included. After diagnostic work up, 98 lesions (8.3%) were malignant, 1083 were non-malignant and a final histologic diagnosis was not established in two lesions. In the 27 months after assessment, no interval cancers were attributable to these lesions and during a mean follow up of 54.5 months, available in 84.9% of eligible women, only one cancer has developed in the same quadrant as the original lesion, although the two processes are believed to be unrelated. FNAB performed in 1149 cases was definitive in 80.5% cases (882 benign, 43 malignant) with a negative predictive value (NPV) of 99.8% (880 of 882) and a positive predictive value (PPV) of 95.2% (40 of 42, both intraductal papillomas). Core biopsy was performed in 178 lesions, mostly for indefinite cytology. Core biopsy was definitive in 79.8% cases (57% benign 22% malignant) with a PPV of 100% and NPV of 99.0%. In experienced hands FNAB is an accurate first line diagnostic modality for the assessment of 3B screen-detected discrete masses, providing definitive results in 80.5% of cases. When used as a second line modality, core biopsy had a similarly high rate of definitive diagnosis at 79.8%. The stepwise approach to the use of FNAB and core biopsy would reduce substantially the proportion of cases requiring surgical diagnostic biopsy. Given the low probability of malignancy and the imperative to limit the morbidity associated with cancer screening, the demonstration of the reliability of FNAB as a minimally invasive but highly accurate test for this particular subset of screen-detected lesions has significant clinical utility.

The fine needle aspiration biopsy diagnostic criteria of proliferative breast lesions: A retrospective statistical analysis of criteria for papillomas and radial scar lesions

This study aimed to analyze statistically the accuracy of fine needle aspiration biopsy cytological criteria in diagnosing epithelial hyperplasia with atypia (EHA), papillary lesions (PAP), and radial scar/complex sclerosing lesions (RS/CSL). The 42 criteria studied were extracted from a literature review and those developed and used in our department. Cytological cases with diagnoses of EHA, PAP, and RS/CSL for the period of 1997-2001 were correlated with relevant histological follow-up and the positive predictive power of these diagnoses have been presented in an earlier publication. Some 77 cases with definite, specific histological diagnoses of atypia or a more severe lesion, PAP and RS/CSL, were reviewed and scored using 55 cytological criteria. As the group of EHA and RS/CSL yielded a smaller number of cases, these were grouped together in the statistical analysis and compared to PAP. The cytological features, which were most diagnostic for PAP, were stellate (Odds ratio 1.75) and meshwork (Odds ratio 3.29) tissue fragments, while the presence of tubular structures was inversely proportional to the histological outcome of PAP. True papillary fragments were uncommon and not statistically significant in diagnosing PAP of the breast.

Positive predictive value of the breast FNAB diagnoses of epithelial hyperplasia with atypia, papilloma, and radial scar

Proliferative breast lesions are a spectrum of lesions that have overlapping cytological features and are difficult to subclassify in fine-needle aspiration biopsies (FNABs). This study of breast FNABs from the period of 1997-2001 aimed to correlate the cytological diagnoses of epithelial hyperplasia with atypia (EHA), papilloma (PAP), and radial scar/complexing sclerosing lesions with relevant histological follow-up, and to assess the positive predictive value (PPV) of the cytological diagnosis. The PPV for the three categories were found to be 0.16, 0.74, and 0.63 respectively. The low value observed in the cytological category of EHA was due to the heterogeneous nature of the group, which makes it difficult to correlate cytological appearances with the varying histological lesions. However, it was found that 70% of these EHA cases had benign histological diagnoses, matching the expected outcome. The PPV of 0.74 for the cytological diagnosis of PAP of the breast compares favorably to similar published studies, and we suggest that the specific diagnosis of PAP can be made reliably using cytological criteria.

Radial scar lesions of the breast diagnosed by needle core biopsy: analysis of cases containing occult malignancy

AIM

To identify and review cases of false negative needle core biopsy (NCB) in the preoperative investigation of radial scar/complex sclerosing lesion (RS/CSL) lesions - that is, benign NCB from RS/CSL which contained malignancy on excision.

METHODS AND RESULTS

A total of 11 false negative NCB in RS/CSL lesions from 281 (3.9%) were identified (6 cases: B1, 2 cases: B2 and 3 cases: B3). In 6 of 11 cases a radial scar or stromal sclerosis was seen in NCB. Localisation biopsy showed duct carcinoma in situ in six cases, duct carcinoma in situ with invasive carcinoma in three and invasive carcinoma in two. In all 11 cases, needle tracks were identified as missing the malignant epithelium by a mean of 5 mm (median:4 mm; range:1-20 mm). In 9 of 11 cases, the malignancy was missed by <6 mm.

CONCLUSIONS

Despite evidence of accurate targeting of lesions, the use of NCB instead of fine needle aspiration cytology has not eliminated the problem of false negative biopsy in RS/CSL, and excision is recommended.

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.

Assessment of 142 Stellate Lesions With Imaging Features Suggestive of Radial Scar Discovered During Population-based Screening for Breast Cancer

Because some lesions diagnosed as radial scars (RS) on core biopsy have been found to be malignant on excision, core biopsy has not had an established role in the assessment of RS. In our breast cancer-screening program, we have avoided core biopsy if RS is suspected on imaging. Recently, two reports have expanded the experience with core biopsy of RS, prompting this review of our assessment protocols for lesions suspected as being RS. Between January 1996 and January 2003, stellate lesions with imaging features of RS in which core biopsy was omitted because of a presumptive radiologic diagnosis of RS are included. Demographic, radiologic, and cytologic data were correlated with the histologic findings in the excised specimen. On imaging, 9% (142) of all stellate lesions were suspected to be RS. Only 66.2% (94) were confirmed as RS on histology; 38 cases (28.6%) were carcinomas (36 invasive, 2 in situ) and 7% showed benign fibrocystic changes; 87.1% of the carcinomas required further surgery for positive margins. Axillary staging was also needed for the invasive cancers. Among the histologically proven RS, 28 of 94 (29.8%) showed areas of atypical ductal hyperplasia, lobular neoplasia, ductal carcinoma in situ, or invasive carcinoma. These proliferations were typically focal and unpredictable and were usually completely excised by the initial diagnostic biopsy. Core biopsy would be valuable in the assessment of lesions with imaging features suggestive of RS since 28.6% of such lesions are indeed carcinomas that mimic RS. Identification of these cancers would permit one stage breast and axillary surgery to be planned. The policy of mammographic surveillance for lesions with nonmalignant core biopsies remains controversial because of the paucity of data. Ongoing evaluation is needed as more experience is reported.

Pathology and clinical relevance of radial scars: a review

Radial scar (RS) is a benign, well recognised, radiological and pathological entity. Histologically, it is characterised by a fibroelastotic core with entrapped ducts and surrounding radiating ducts and lobules. Postmortem studies indicate that these lesions are present commonly in the population, especially in association with benign breast disease. In recent years, their clinical relevance has assumed more importance with the introduction of population based screening programmes. The exact pathogenesis of RS is unknown. Accumulating evidence indicates that they are associated with atypia and/or malignancy and, in addition, may be an independent risk factor for the development of carcinoma in either breast. In view of the association with atypia and malignancy, excision biopsy is justified in RS, although it has been argued that core biopsy evaluation and surveillance may be appropriate in selected patients.

The diagnosis and management of pre-invasive breast disease: the role of new diagnostic techniques

In recent years we have seen significantly increased use of minimally invasive diagnostic techniques in the management of breast disease. There is wide recognition of fine needle aspiration and core biopsy as the principal diagnostic methods. However, concerns exist regarding their reliability. This article provides a brief overview of the major diagnostic issues related to use of fine needle aspiration, core biopsy and ductal lavage. It summarizes areas of use for each technique, outlines the main diagnostic pitfalls and their causes, and provides a perspective on future developments in the field.

False-positive reports in fine needle biopsy of breast lesions

A review of the literature reveals considerable variations in the diagnostic accuracy of fine needle biopsy (FNB) of breast lesions between series, partly due to different methods of calculation, different definitions, and insufficient numbers of cases with adequate follow-up to provide reliable statistics. The best larger series have a false-positive rate between 0.2 and 0.3%, slightly higher for non-palpable than for palpable lesions. The cytological patterns of a range of benign lesions which may cause diagnostic difficulties and may be misdiagnosed as malignant by FNB are described, and guidelines to reduce the risk of false-positive diagnoses are proposed.

Critical clinicopathologic analysis of 23 cases of fine-needle breast sampling initially recorded as false-positive. The 44-year experience of the Institut Curie

BACKGROUND

Because false-positive cytologic diagnoses in breast tumors are rare, few cases have been reported, although their consequences may be highly detrimental to the patient. The authors report the Institut Curie's experience, by using a multidisciplinary approach.

METHODS

Of 9334 benign breast tumors examined preoperatively for cytologic diagnosis by fine-needle sampling (FNS), the 23 (0.25%) FNS cases considered to be false-positive were retrospectively reviewed and analyzed.

RESULTS

Tumors were situated close to the nipple in 7 cases and away from the nipple in 16 cases. Tumor stage was T0 for 1 case, T1 for 18 cases, and T2 for 4 cases. Radiologically, six tumors were classified as malignant, seven as indeterminate or suspicious, and nine as benign. Three of six tumors studied by flow cytometry were DNA aneuploid. Based on a multidisciplinary clinicopathologic review, 20 FNS cases were finally classified as false-positive, and the remaining 3 tumors with malignant FNS and subsequent benign histology were classified as true-positive, because local and/or metastatic progression was observed in the short term.

CONCLUSIONS

The authors' review suggests two categories of false-positive cases: the first in which cytologic benign patterns are overdiagnosed, and the second in which atypical morphologic criteria were present. Nevertheless, as shown by the malignant course in three cases, patients with malignant preoperative FNS and corresponding benign histology always require close clinical follow-up. Finally, surgical overtreatment rate could be decreased if all radiologically benign tumors with positive/suspicious FNS were subject to intraoperative frozen section examination.