Fine needle aspiration cytology of breast fibroadenoma. A cytohistologic correlation study of 405 cases

Mammary mesenchymal and fibroepithelial lesions: An illustrated cytomorphologic update with differential diagnoses

The Uniform Approach to Breast Fine Needle Aspiration Biopsy was put forward by a learned group of breast physicians in 1997. This landmark manuscript focused predominantly on diagnosis and reporting of mammary epithelial lesions. Today, most American practitioners turn initially to core biopsy rather than aspiration biopsy for the first line diagnosis of solid breast lesions; however, recent efforts from the International Academy of Cytology have produced a system called the Standardized Reporting of Breast Fine Needle Aspiration Biopsy Cytology (colloquially labeled in 2017 as the "Yokohama System"), suggesting a new interest in breast fine needle aspiration (FNA), especially in resource limited settings or clinical practice settings with experienced breast cytopathologists. Fibroepithelial lesions of the breast comprise a heterogeneous group of biphasic tumors with epithelial and stromal elements. Mesenchymal lesions of the breast include a variety of neoplasms of fibroblastic, myofibroblastic, endothelial, neural, adipocytic, muscular, and osteo-cartilaginous derivations. The cytology of mesenchymal breast lesions is infrequently described in the literature and is mainly limited to case reports and small series. This illustrated review highlights the cytologic features of fibroepithelial and mesenchymal mammary proliferations and discusses differential diagnoses and histomorphologic correlates.

Sub-classification of Breast Masses by Fine Needle Aspiration Cytology

OBJECTIVE

The aim of this study is to evaluate the accuracy of sub-classification of breast diseases using Fine Needle Aspiration cytology (FNAC).

MATERIALS AND METHODS

A one-year prospective study of 180 consecutive patients with palpable breast lesions who underwent FNAC and subsequently open surgical biopsy for histological confirmation. FNAC was used to sub-classify breast lesions and then correlated with histological diagnosis.

RESULTS

A total of 180 patients were enrolled into the study but only 110 patients with histology report were used for test validity. Seventeen (15.5%) smears were C1; while 46 (41.8%), 5 (4.5%), 4 (3.6%) and 38 (34.6%) were C2, C3, C4 and C5, respectively. FNAC achieved sensitivity of 90.0%, specificity of 95.5%, false positive rate of 5.3%, false negative rate of 8.7%, positive predictive value of 94.7%, negative predictive value of 91.3% and overall diagnostic accuracy of 92.9%. Only 86 (78.2%) of the 110 smears could be sub-classified into different disease conditions of the breast on cytology. FNAC accurately sub-classified 25(78.1%) of fibroadenoma and 28(87.5%) of invasive ductal carcinoma.

CONCLUSION

FNAC can reasonably sub-classify fibroadenoma, invasive ductal carcinoma and mastitis but there is still a challenge with lobular carcinomas, metaplastic carcinomas, papillary carcinomas and fibrocystic changes.

[Common benign breast tumors including fibroadenoma, phyllodes tumors, and papillary lesions: Guidelines]

OBJECTIVES

To provide guidelines for clinical practice from the French College of Obstetrics and Gynecology (CNGOF), based on the best evidence available, concerning common benign breast tumors: fibroadenoma (FA), phyllodes breast tumors (PBT), and papillary lesions (BPL).

METHODS

Bibliographical search in French and English languages by consultation of PubMed, Cochrane and international databases.

RESULTS

In case of percutaneous biopsy diagnosis of FA, clinico-radiologic and pathologic discordance or complex FA or proliferative lesions or atypia with FA, a family history of cancer, it seems legitimate to discuss management in a multidisciplinary meeting. When surgery is proposed for FA, periareolar compared to direct incision is associated with more insensitive nipple but better aesthetic results (LE4). When surgery is proposed for FA, indirect incision is preferable for better cosmetic results (Grade C). Techniques of percutaneous destruction or resection can be used (Grade C). The WHO classification distinguishes three categories of phyllodes tumors (PBT): benign (grade 1), borderline (grade 2) and malignant (grade 3). For grade 1 PBT, the risk of local recurrence after surgical excision increases when PBT lesion is in contact with surgical limits (not in sano). After in sano resection, there is no correlation between margin size and the risk of recurrence (LE4). For grade 2 PBT, local recurrence after surgical excision increases for margins under 10mm margins (LE4). For grade 1-2 PBT, in sano excision is recommended. For grade 2 PBT, 10-mm margins are recommended (Grade C). No lymph node evaluation or neither systematic mastectomy is recommended (Grade C). Breast papillary lesion (BPL) without atypia, complete resection of radiologic signal is recommended (Grade C). For BPL with atypia, complete excisional surgery is recommended (Grade C).

Cytological features of complex type fibroadenoma in comparison with non-complex type fibroadenoma

BACKGROUND

To determine the cytomorphological features of complex type fibroadenoma (CFA), we reviewed fine needle aspiration (FNA) cytology with correlation to its histopathology findings, and compared them with non-complex type fibroadenoma (NCFA).

METHODS

From excisional biopsy or resected specimens of fibroadenoma (FA) cases treated at our institution from 2004 to 2013, we chose 46 patients who underwent FNA before a diagnosis of FA was established. We histologically re-classified them into two groups: CFA and NCFA. FNA diagnosis was retrospectively re-evaluated from FNA reports. We further re-assessed detailed characteristics of each FNA smears to identify cytomorphological features of CFA.

RESULTS

We found that 15 cases fulfilled the diagnostic criteria of CFA, in which 7 (46.7 %) had an FNA diagnosis of "suspicious for malignancy" or "indeterminate" while only 2 NCFA cases had that of "indeterminate" (p = 0.004). FNA smears from CFA cases showed discohesiveness, enlarged nuclei, prominent nucleoli, and fewer myoepithelial cells more often than NCFA. Although no significant difference was noted in patients' age and tumor size between CFA and NCFA, 5 CFA cases (33.3 %) were accompanied by the presence of carcinoma in the same breast or the contralateral breast while no NCFA cases had carcinoma in the breast.

CONCLUSIONS

FNA of CFA can lead to erroneous or indeterminate interpretation, due to proliferative and/or hyperplastic changes of ductal epithelium with or without atypia. It is important to recognize the disease entity and characteristic cytomorphological findings of CFA to reach accurate FNA diagnosis of breast lesions.

Fine-needle aspiration of gray zone lesions of the breast: fibroadenoma versus ductal carcinoma

While breast lesions have characteristic cytological features, some lesions, particularly adenocarcinoma and fibroadenoma, may present with overlapping features causing erroneous diagnoses. The current study aimed to define significant cytomorphologic features predictive of fibroadenoma and adenocarcinoma, respectively. Further, we intended to evaluate the predictive characteristics for differentiation between gray zone lesions and to identify root causes contributing to misdiagnoses. First, direct smears prepared from 14 histology-confirmed fibroadenomas and 14 adenocarcinomas were reviewed and characteristics of commonly encountered morphologic features were assessed. We then retrospectively and blindly reviewed nine cytohistologic discrepant cases using the significant characteristic as a guideline, in order to assess whether these discrepant cases could be correctly categorized. Morphologic characteristics predictive of fibroadenoma included moderate cellularity, large, folded cellular sheets/aggregates, staghorn projections, smooth and round borders, monolayers, honeycomb arrangement, smaller nuclear size, and background bipolar cells. Predictive characteristics of adenocarcinoma included high cellularity, loose cohesive sheets/aggregates, pointed projections, irregular borders, larger nuclear size, irregular nuclear membrane, prominent nucleoli, and single atypical epithelial cells. Retrospective, blind review correctly re-classified seven out of nine cytohistologic discrepant cases, including five false negative cases and two false positive cases. Root causes contributing to the misdiagnoses were large branching sheets of carcinoma mimicking folded sheets of fibroadenoma; fibroblasts mimicking myoepithelial cells; apocrine cells mimicking carcinoma cells; and not recognizing the loose myxoid matrix presenting as soap bubbles in fibroadenoma. In conclusion, this study identified significant characteristics that can assist in achieving accurate diagnosis in a subpopulation of breast aspirates that present with overlapping features.

Performance Characteristics of Mucinous (Colloid) Carcinoma of the Breast in Fine-Needle Aspirates: Observations From the College of American Pathologists Interlaboratory Comparison Program in Nongynecologic Cytopathology

Context.—Mucinous breast carcinoma has characteristic cytologic features, but few studies exist that analyze the reproducibility of this diagnosis.

Objective.—To analyze participants' diagnosis of mucinous carcinoma in breast fine-needle aspiration (FNA) slides distributed in an educational interlaboratory peer comparison program.

Design.—Participant responses for FNA slides with a reference diagnosis of mucinous carcinoma, distributed between 2001–2008 in the College of American Pathologists Interlaboratory Comparison Program in Nongynecologic Cytopathology, were evaluated for concordance with the general category and reference diagnosis of mucinous carcinoma.

Results.—Of 8061 responses, 6353 (78.8%) were categorized as malignant; 775 (9.6%) as suspicious; and 933 (11.6%) as negative. The most frequent incorrect responses for the benign category included fibroadenoma (51.7%), nonspecified benign lesion (12%), fibrocystic changes (7.8%), and fat necrosis/granulomatosis/foreign body reaction (6.9%). Conventional Papanicolaou-stained preparations were reviewed for 58.7% (4732) of responses; of these, 39.4% (3177) were from modified Giemsa–stained smears and 1.9% (152) from ThinPrep slides. Papanicolaou-stained conventional smears had the lowest concordance (86.5%) when compared to modified Giemsa–stained smears (91.2%) and ThinPrep challenges (92.1%) (P < .001). Participants specifically diagnosed mucinous carcinoma 37.3% of the time, and modified Giemsa–stained challenges performed best (43.1%, P < .001). There was no significant difference between cytotechnologists' and pathologists' responses (87.9% versus 88.2%; P  =  .69).

Conclusions.—Mucinous carcinoma in FNA was not accurately identified in a glass slide interlaboratory comparison program. We observed better performance with modified Giemsa–stained and ThinPrep slides than with Papanicolaou-stained preparations. The most common response for the benign category of mucinous carcinoma was fibroadenoma. Increased awareness of the cytologic features of mucinous carcinoma may improve accuracy in breast FNA.

First case of transformation for breast fibroadenoma to high-grade malignant cystosarcoma in an in vitro fertilization patient

OBJECTIVE

To evaluate the possible malignant transformation of fibroadenoma of the breast in patients undergoing an IVF cycle.

DESIGN

Case report.

SETTING

Assisted reproduction center.

PATIENT(S)

A 41-year-old female patient undergoing assisted fertilization treatment.

INTERVENTION(S)

The patient underwent fine needle aspiration biopsy that confirmed fibroadenoma before the IVF attempt. She started a short stimulation protocol with triptorelin and recombinant FSH. After the first unsuccessful IVF attempt, she underwent a second short ovarian stimulation protocol with triptorelin and urinary FSH and she become pregnant. At 17 weeks, due to an increase in volume of the fibroadenoma, an excisional biopsy was performed that showed a malignant phyllode tumor. Then she underwent quadrantectomy.

MAIN OUTCOME MEASURE(S)

Malignant transformation of breast fibroadenoma.

RESULT(S)

Cytologic examination of the first fine needle aspiration biopsy specimen showed a fibroadenoma of the breast; excisional biopsy showed a high-grade malignant cystosarcoma.

CONCLUSION(S)

Fibroadenoma was transformed into high-grade malignant cystosarcoma after ovarian stimulation in an IVF patient.

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.

Fine needle aspiration cytology of the breast: the nonmalignant categories

Currently, accurate diagnosis of breast lesions depends on a triple assessment approach comprising clinical, imaging and pathologic examinations. Fine needle aspiration cytology (FNAC) is widely adopted for the pathologic assessment because of its accurracy and ease of use. While much has been written about the atypical and maliganant categories of FNAC diagnosis, little covers the non-malignanat category which represents a sheer number in all FNAC cases. Moreover, any false-negative diagnosis of the non-malignant cases may lead to missed diagnosis of cancer. This paper aims to discuss the issues of smear adequacy, the cytologic features of benign breast lesions and the dilemma of a false-negative aspirate. Much has been suggested about the smear adequacy criterion, including quantifying epithelial clusters, whereas others advocate basing adequacy on qualitative quantum of using noncellular features of FNAC. Various benign lesions could be easily diagnosed at FNAC; however, they have cytologic features overlapped with malignant lesions. False negativity of FNAC does occur; this could be caused by either “true” false-negative cases attributed to suboptimal sampling technique, poor localization of the mass or nonpalpable lesions or “false” false-negative cases due to interpretational errors. Though false-positive cases are less commonly found, they will also be discussed briefly.

Fine-needle aspiration cytology of mammary fibroadenoma: a comparison of ThinPrep® and cytospin preparations

Mammary fibroadenoma (FA) is a lesion frequently sampled and diagnosed by fine-needle aspiration (FNA). Accurate cytologic diagnosis of this common benign lesion is important as this can lead to non-surgical, conservative management when breast imaging and clinical examination are concordant. In most instances, a confident diagnosis of FA is possible because of a characteristic cytologic appearance that includes hypercellularity, large epithelial cell groups, staghorn epithelial configurations, stromal fragments, and numerous background stripped nuclei. Nevertheless, FAs can be diagnostically challenging because of shared cytomorphologic features with other benign lesions and low-grade carcinoma. As such, FA is a well-recognized source of false results on FNA cytology. Furthermore, there are reports that newer thin layer cytopreparatory techniques, including the ThinPrep® (TP) system (Hologic Corp., Bedford, MA), alter the appearance of FA on FNA compared to conventional preparations and may compromise accurate cytologic diagnosis.

WCAFTI: worrisome cytologic alterations following tissue infarction; a mimicker of malignancy in breast cytology

The acronym WCAFTI (cafti)-(Worrisome cytologic alterations following tissue infarction) is introduced here for the first time for the entity which describes the spectrum of cytologic changes seen in spontaneous infarction of an epithelial lesion. The pathology may be responsible for abnormal cytologic findings such as cellular dyshesiveness, nuclear enlargement with cytoplasmic blurring and irregular nuclei. Although, it is a rare event, it is essential for a cytologist to be aware of this new acronym WCAFTI to avoid misinterpretation of atypical cells and necrosis as indicators of malignancy. It is typically described here in a fibroadenoma from a 49-year-old female who sought medical help for pain in left breast mass.

RHEB expression in fibroadenomas of the breast

Although fibroadenoma is one of the most common types of benign breast tumor, genes specific to the tumor have not been identified. Microarrays were used to identify differentially expressed genes between fibroadenoma and infiltrating ductal carcinoma. The comparative expression of one of the identified genes, RAS homolog enriched in the brain (RHEB), was further explored using reverse transcriptase-polymerase chain reaction (RT-PCR). Microarray analysis was performed on tissue samples from five patients with fibroadenoma. In the fibroadenoma samples, the genes HDAC1, ROS1, TNFRSF10A, WASP2, TYRP1, WEE1, and RHEB were expressed at levels more than twofold higher than in the normal tissues. RT-PCR for RHEB indicated increased expression of RHEB in fibroadenoma compared to breast cancer. When studied with real-time PCR, the average RHEB/beta-actin ratio in fibroadenoma samples was 1.99, 2.46-fold greater than the average RHEB/beta-actin ratio in breast carcinoma of 0.81 (P < 0.01). Immunohistochemistry and PCR followed by microdissection shows increased expression of RHEB in epithelial cells compared to the stromal cells of fibroadenoma. Therefore, RHEB could be used cytopathologically to distinguish fibroadenoma from malignant breast carcinomas as a secondary diagnostic tool.

Mastopathic fibroadenoma of the breast: a pitfall of aspiration cytology

OBJECTIVE

To assess the correlation between cytological diagnoses and histological subtypes of fibroadenoma (FA) and to clarify the cytological features of a specific group of FA displaying variable features similar to fibrocystic disease (mastopathic type, MFA), and to evaluate the significance of this subtype in cytological diagnosis.

METHODS

A review of 141 cases of histologically proven FA was performed. We re-classified them into four subtypes according to Kinoshita's criteria [Jpn J Breast Cancer6 (1991) 377] and further selected 92 cases for which both fine needle aspiration (FNA) smears and histological specimens were available. Among them, 18 cases of MFA and their cytological smears were selected for the present study.

RESULTS

There was significant correlation between MFA and cytological diagnosis of 'indeterminate' or 'suspicious for malignancy' (P < 0.01). Although no false-positive diagnosis was experienced in our series, 56% of the MFAs (10/18) had cytological diagnoses of indeterminate or were included in the category 'suspicious for malignancy'. Smears from MFA revealed high cellularity (9/18 smears had more than 10 epithelial clusters each composed of more than 50 cells), presence of cellular discohesiveness (13/18, 72.2%), but only mild nuclear atypia (5/18, 27.8%). Anisonucleosis was present in fewer than half the cases and no apparent condensed chromatin was identified.

CONCLUSION

We highlight the significance of subclassification of MFA in aspiration cytology of breast. MFA had a significantly higher chance of falling into the 'suspicious for malignancy' or 'indeterminate' diagnostic category in aspiration cytology. It might be a diagnostic challenge for cytopathologist to identify this subtype of FA in FNA smears.

FNA of breast fibroadenoma: observer variability and review of cytomorphology with cytohistological correlation

OBJECTIVE

To determine the observer variability in reporting fibroadenoma of the breast by fine needle aspiration (FNA) and to review the cytomorphological features of the lesion with cytohistological correlation.

METHODS

Retrospective analysis of FNA smears from 110 cases diagnosed as fibroadenoma of which surgical pathology follow-up was available in 33. Two pathologists were asked to categorize smears from 67 cases of breast lesions while blinded to the clinical finding as fibroadenoma, epithelial hyperplasia (usual and atypical) and malignant. All fibroadenoma (33) and cancer (15) cases were biopsy-proven. The same set of slides was re-circulated to one of the pathologists, and his first and second round results were compared.

RESULTS

Pre-review cytohistological correlation was attained in 32 of 33 cases of fibroadenoma (97%). The overall agreement between the two observers was 87% [Kappa = 0.74, 95% confidence interval (CI) 0.72-0.76]. Cytohistological correlation was achieved in 26 of 33 (79%) cases. Intra-observer agreement was 91% (Kappa = 0.82, 95% CI 0.89-0.93) with cytohistological correlation in 29 of 33 (87%) cases. Causes of diagnostic errors included marked dissociation, pleomorphism, poorly cellular smears from hyalinized fibrodenoma, lacational changes and apocrine metaplasia with cystic changes. Multinucleated giant cells were frequently encountered in FNA smears from fibroadenoma (31.8%), but in none of the lumpectomy specimens. Their histiocytic nature was suggested by immunohistochemistry.

CONCLUSION

FNA was a highly sensitive method for the diagnosis of fibroadenoma. Current cytological criteria were reliable and gave high inter- and intra-observer reproducibility.

Fine needle aspiration cytology of mammary carcinoma with osteoclast-like giant cells

Carcinoma with osteoclast-like giant cells (OCGC) is an uncommon neoplasm characterized by giant cells, prominent vascularization, haemorrhage and areas of cribriform epithelial growth with moderate atypia. Multinucleated giant cells (MGC) have been described in several other breast lesions raising an interesting differential diagnosis, mainly with benign disorders. Due to its rarity few cases have been described cytologically. We retrospectively reviewed 13 fine needle aspiration samples from nine patients with this variant of carcinoma. Nine corresponded to breast tumours and four to axillary, liver, subcutaneous and mediastinal metastatic lesions. The expression of CD68 by giant cells was evaluated immunocytochemically in six cases. All patients had a complete pathological study of the breast neoplasm. Smears showed a double component of epithelial and giant cells. Epithelial clusters were predominantly of intermediate size with irregular contours. Most were cohesive but others showed cellular dissociation with scarce to moderate cellular pleomorphism. Giant cells had well defined, deeply stained cytoplasm and round to elongated morphology. Two metastatic cases were devoid of them. Haemosiderin-laden macrophages were common in smears from breast tumours. In the six cases tested CD68 was expressed in MGC. Cytological features of mammary carcinoma with OCGC correlate closely with the histological ones. Most cases are clearly recognizable as malignant but in others cytological atypia may be minimal, mimicking a benign lesion. In difficult cases the presence of haemosiderin-laden macrophages and the histiocytic nature of the MGC are helpful diagnostic features.

Simulation modeling of change to breast cancer detection age eligibility recommendations in Ontario, 2002-2021

PURPOSE

The purpose of this project was to demonstrate the development and use of a decision support tool based on simulation modeling of breast cancer screening to evaluate the implications for the provision of health services and the economic impact of extending routine radiographic screening for breast cancer to women in the 40-49 age group between 2002 and 2021.

METHODS

The main method was computer simulation with a Markov model that used published estimates of population size by age group, breast cancer prevalence and incidence, screening program participation rate, sensitivity and specificity of the screening test and diagnostic test, stage transition probabilities, directed diagnosis rates and costs.

FINDINGS

The model predicted that changes to age eligibility requirements would result in the detection of an additional 6610 women with breast cancer in Ontario requiring treatment, at an additional cost of 795 Canadian per case. These costs include those related to screening, diagnosis and initial treatment and apply to the 20-year period.

CONCLUSIONS

The model provided a useful decision support tool for those planning and implementing breast cancer screening programs.

Atypical squamous metaplasia of seromas in breast needle aspirates from irradiated lumpectomy sites: a potential pitfall for false-positive diagnoses of carcinoma

The presence of squamous metaplasic cells is an uncommon finding in fine-needle aspiration (FNA) biopsies of the breast. We report that FNA smears containing atypical squamous metaplastic cells derived from the lining of seroma-type cavities following lumpectomy and irradiation in patients with breast cancer can be a potential pitfall for a false-positive diagnosis of recurrent malignancy. Four fine-needle breast aspirates from two adult patients with previous histories of invasive breast carcinoma were retrieved. One specimen was from a 56-yr-old female, while the remaining three FNAs aspirates were from a 75-yr-old female. Both patients presented with indurated cystic lesions arising at irradiated lumpectomy sites. The cytospins from the 56-yr-old patient showed markedly atypical cells having enlarged, degenerating, hyperchromatic nuclei and surrounding dense cytoplasm with sharp borders that were suspicious for carcinoma. A mastectomy revealed irradiation changes and atypical squamous metaplastic cells lining a cystic cavity consistent with a seroma, but there was no evidence of residual cancer. After three aspirations yielded "atypical" diagnoses, the second patient underwent core needle biopsies that also revealed changes consistent with a seroma cavity lined by atypical squamous metaplastic cells. We believe this is the first report of squamous metaplasia occurring in a seroma cavity following lumpectomy and irradiation of the breast. The squamous metaplastic cells in aspirates of these cystic lesions may display significant cellular atypia that can potentially result in a false-positive diagnosis of malignancy.

Fibroadenomas with atypia: causes of under- and overdiagnosis by aspiration biopsy

Fibroadenoma (FA) is a common benign breast lesion frequently sampled by fine-needle aspiration biopsy (FNAB). Although the cytologic diagnosis is straightforward in most cases, cellular discohesion and atypia in FAs may lead to falsely atypical or positive FNAB diagnoses. Conversely, some adenocarcinomas mimic a fibroadenomatous pattern on FNAB, resulting in a false-negative diagnosis. We reviewed the cytologic and histologic findings in 25 cases with a preoperative FNAB diagnosis of FA, wherein excision was recommended based on atypia. Our aim was to analyze the spectrum of changes causing under- or overdiagnosis in such cases. The smears were assessed for cellularity, cellular discohesion, presence of dissociated intact cells and nucleoli, nuclear pleomorphism, oval bare nuclei, and stromal fragments. The histologic findings were correlated with FNAB features. At excision, 88% of FAs classified as atypical on FNAB were benign (FA with ductal hyperplasia and lactational change, myxoid FA, and other fibroepithelial lesions). Differentiating myxoid FA from colloid carcinoma was difficult due to the abundance of extracellular mucin in which the dissociated epithelial cells were floating. Two (8%) cases were carcinomas on excision; the reasons for underdiagnosis in one case reflected sampling, and in the other, interpretative error. There was one (4%) benign phyllodes tumor which lacked stromal fragments and single stromal cells on FNAB smears. The lesion was called atypical, based on the epithelial discohesion on the smears. We conclude that the majority of FAs with atypia on FNAB are benign lesions. Considering the grave consequences of a false-positive cytologic diagnosis, we recommend a conservative approach in interpreting FNAB smears which overall display a fibroadenomatous pattern.

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.