Correlation of p53 and MIB-1 expression with both the systemic recurrence and survival in cases of phyllodes tumors of the breast

The Genetic Landscape of Fibroepithelial Lesions of the Breast

Fibroepithelial lesions of the breast encompass a broad spectrum of lesions from fibroadenomas and their variants to phyllodes tumors, including their clinical range of benign, borderline, and malignant. Classification of this spectrum of neoplasms has historically and currently been based purely on morphology, although the nomenclature has shifted over the years largely due to the significant histologic overlap that exists primarily within the cellular fibroadenomas to borderline malignant phyllodes tumor categories. A review of the current diagnostic challenge, proposed ancillary studied and their value in prognostic significance, is provided. This article highlights the most recent molecular and genetic findings as well as the limitations of the studies, in the context of practical and available applications for the diagnostician and managerial implications for the clinician.

Clinical perspectives and outcomes of the giant breast phyllodes tumor and sarcoma: a real-world retrospective study

BACKGROUND

Giant breast malignant phyllodes tumor or sarcoma (GBPS) are rare entities with diameter larger than 10 cm and variously histological pleomorphisms. This disease poses a significant threat to the quality of life of individuals, and its prognosis remains unclear. This study aimed to explore the differential diagnosis, treatment, and prognosis of GBPS in a real-world retrospective cohort.

METHODS

We collected GBPS (diameter > 10 cm, n = 10) and BPS (diameter ≤ 10 cm, n = 126) from patients diagnosed with sarcoma or malignant phyllodes tumor between 2008 and 2022. We analyzed clinical characteristics, histological status, treatment, and local recurrence using the Fisher's exact test between GBPS (diameter > 10 cm) and BPS (diameter ≤ 10 cm) cohort. We described overall survival (OS) and disease-free survival (DFS) using Kaplan-Meier curves and identified risk factors for local recurrence using logistic regression. The tumor size, age at diagnosis, and differential immunohistochemistry markers of breast sarcoma or phyllodes tumor to determine the prognosis of GBPS.

RESULTS

In our retrospective analysis of breast malignancies, we identified 10 cases of GBPS and 126 cases of BPS, corresponding to a GBPS prevalence of 0.17% (10/6000). The median age was 38.5 years (inter-quartile range, IQR: 28.25-48.5 years). During the follow-up of period (median: 80.5 months, IQR: 36.75-122 months), the local recurrence (LR) rate was 40% and 20.6%, respectively. Clinical characteristics of young age (HR:2.799, 95%CI -00.09276-0.017, p < 0.05) and cytological characteristics of marked stromal atypia (HR:0.88, 95% CI 0.39-1.40, p < 0.05) were risk factors for the poor prognosis of GBPS by COX regression model analysis. The Kaplan-Meier curves of GBPS 5-year disease-free survival (DFS) and overall survival (OS) were 31.5 months and 40 months, respectively, and were not associated with adjuvant radiation or chemotherapy.

CONCLUSION

We recommend mastectomy with a clear surgical margin as the preferred treatment for GBPS. Age and stromal atypia are significantly associated with recurrence. Adjuvant radiation therapy is advised; however, there was no improvement in overall survival. There is no consensus on the effectiveness of adjuvant chemotherapy and genetic methods, highlighting the need for further research into this aggressive tumor. We recommend a multidisciplinary approach involving a dedicated team for the management of GBPS.

Breast Sarcomas, Phyllodes Tumors, and Desmoid Tumors: Turning the Magnifying Glass on Rare and Aggressive Entities

Breast sarcomas (BSs), phyllodes tumors (PTs), and desmoid tumors (DTs) are rare entities that arise from connective tissue. BSs can be classified as either primary or secondary, whether they develop de novo or after radiation exposure or lymphedema. PIK3CA seems to play an important common role in different BS. Malignant PTs show similar behavior to BSs, while DTs are locally aggressive but rarely metastasize. BSs usually present as unilateral, painless, rapidly growing masses with rare nodal involvement. The diagnosis should be based on magnetic resonance imaging and a core needle biopsy. Staging should comprise a chest computed tomography (CT) scan (except for benign PT and DT), while abdominal and pelvic CT scans and bone scans should be added in certain subtypes. The mainstay of treatment for localized BS is surgery, with margin goals that vary according to subtype. Radiotherapy and chemotherapy can be used as neoadjuvant or adjuvant approaches, but their use in these settings is not standard. Advanced BS should be treated with systemic therapy, consistent with recommendations for advanced soft tissue sarcomas of other topographies. Given the rarity and heterogeneity of these entities, multidisciplinary and multi-institutional collaboration and treatment at reference centers are critical.

Clinical outcomes and biomarkers of phyllodes tumors of the breast: A single-center retrospective study

PURPOSE

Phyllodes tumors (PTs) are rare neoplasms with a certain risk of recurrence and/or metastasis. In clinical practice, there is a lack of high-quality clinical studies and unified guidelines to guide the treatment.

MATERIALS AND METHODS

All malignant and recurrence/metastasis PTs were retrospectively collected, which were diagnosed from 2008 to 2022.

RESULTS

A total of 82 patients were enrolled, including 69 malignant and 13 borderline tumors. 96.3% (79/82) received surgical treatment. During a median follow-up of 55.5 months, 20 patients (20/82, 24.4%) had distant metastasis (DM), while 32 (32/82, 39.0%) had local recurrence (LR). Univariate analysis showed the survival of PTs was associated with surgical methods (p < 0.001), tumor size (p = 0.026), and biological behavior (p = 0.017), but not age at diagnosis. In relapsed borderline PTs, we did not find deaths due to disease progression. Patients with DM were all malignant PTs, with disease-progression occurring within 3 years in more than 80% of patients. Among salvage treatments, the combination of antiangiogenic drugs improved the prognosis to some extent, with a significant increase in mPFS (2.77 vs. 1.53 months), but no significant statistical results were obtained (p = 0.168). Lactate dehydrogenase (LDH) was an independent predictor of the prognosis for malignant PTs (p = 0.001, HR = 1.203, 95%CI, 1.082-1.336).

CONCLUSION

Borderline PTs rarely metastasize, and even if LR occurs, surgical resection can lead to long-term survival. In metastatic phyllodes tumors (MPT), systemic therapy is not effective, but antiangiogenic drugs may prolong survival. LDH is an independent prognostic factor for malignant PTs to identify high-risk tumors.

Phyllodes Tumors: A Scoping Review of the Literature

PURPOSE

Phyllodes tumors are rare tumors of the breast, with most literature being retrospective with limited guidelines on the management of these patients. Scoping review was performed to highlight themes and gaps in the available literature.

METHODS

A scoping review of the literature was performed as per PRISMA-ScR guidelines with titles, abstracts, and full texts reviewed in duplicate. Data were abstracted and summarized in categories of diagnostics, surgical management, adjuvant therapies, treatment of recurrence, and surveillance. Quality assessment was performed for each paper.

RESULTS

The search identified 4498 references, 434 full-text papers were reviewed, and 183 papers were included. Ultrasound, magnetic resonance imaging, and core needle biopsy are valuable preoperative diagnostics tools. Pathology reporting should include stromal overgrowth, stromal cellularity, nuclear atypia, mitotic rate, borders, and presence of heterologous elements. Ki67 may have a role in grading and prognosticating. Breast conservation is safe in all grades of phyllodes but may be associated with increased local recurrence in malignant phyllodes. Surgical margins should depend on grade. Axillary node positivity rate is very low, even with clinically enlarged lymph nodes. Adjuvant radiation is a useful tool to decrease local recurrence in malignant phyllodes tumors, tumors > 5 cm, age < 45 years, close margins, and breast conservation. There is no evidence supporting adjuvant chemotherapy. Recurrence can be managed with repeat wide excision; however, mastectomy is associated with lower re-recurrence. Surveillance protocols are variable in the literature.

CONCLUSIONS

There is heterogeneity in the literature on phyllodes tumors. Consensus guidelines based on the literature will help provide evidence-based care.

Extramammary Borderline Phyllodes Tumor Presenting as an Umbilical Mass

Phyllodes tumors (PTs) represent a spectrum of rare, fibroepithelial neoplasms of the breast, which can be subcategorized as benign, borderline, or malignant based on their histological appearance. Accessory breast tissue may present anywhere along the embryological mammary ridge, and at distant locations as aberrant breast tissue. We present the case of a 56-year-old lady with an umbilical mass, thought to represent a strangulated hernia. Sections showed a fibroepithelial tumor with leaf-like ducts, conspicuous mitotic activity (up to 8 per 10 high-power fields), and focal infiltration into fat. Immunohistochemical studies showed diffuse positivity of epithelial cells for estrogen receptor, mammaglobin, GCDFP-15, and CK7. These findings were consistent with a borderline PT. This is the first case report of PT presenting as an umbilical mass, and the first extramammary borderline PT described.

Histopathologic, immunophenotypic, and proteomics characteristics of low-grade phyllodes tumor and fibroadenoma: more similarities than differences

Distinguishing low-grade phyllodes tumor from fibroadenoma is practically challenging due to their overlapping histologic features. However, the final interpretation is essential to surgeons, who base their management on the final pathology report. Patients who receive a diagnosis of fibroadenoma might not undergo any additional intervention while lumpectomy with wide margins is the standard of care for phyllodes tumor, which can have significant cosmetic consequences. We studied the clinical, immunophenotypic, and proteomics profiles of 31 histologically confirmed low-grade phyllodes tumor and 30 fibroadenomas. Matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS) and immunohistochemistry for Ki-67, p53, β-catenin, and E-cadherin were performed on all cases. After the mass spectra for all 31 cases of low-grade phyllodes tumor and 30 cases of fibroadenoma were collected, an average peak value for all cases was generated. There was no significant difference in the overall mass spectra pattern in any of the peaks identified. There was also overlap in the percentage of cells staining positive for Ki-67, p53, β-catenin, and E-cadherin. The two groups of patients showed no statistically significant difference in age, tumor size, or disease-free survival. Neither group developed malignant transformation, distant metastases, or disease-related mortality. We have demonstrated low-grade phyllodes tumor and fibroadenoma to show significant overlapping clinical and proteomics features.

Accuracy of p53 and ki-67 in the graduation of phyllodes tumor, a model for practical application

Background

The accurate graduation of a phyllodes tumor (PT) is critical for effective treatment as it allows correct surgical management, and avoids inadequate excision for malignant or borderline PT, or surgical overtreatment in benign PT. PTs of the breast are notoriously difficult to classify, and reliable differentiation of a benign PT from a borderline or malignant PT can be problematic, especially among relatively inexperienced pathologists. Although several authors acknowledge a strong relationship between the immunohistochemical expression of p53 and Ki-67 and the histopathological grade of PT—with potential impact on diagnostic accuracy—the literature lacks consensus about which cutoff defines a positive index test. The objective of this study is to establish a practical application score that increases the graduation accuracy of PT through the appropriate use of these auxiliary methods.

Methods

A retrospective study cohort of 146 pathology reviewed PTs surgically removed between January 2000 and December 2015. The Ki-67 test was considered positive if > 10% of neoplastic cells showed nuclear staining. The p53 test was considered positive if > 10% of neoplastic nuclear cells showed nuclear staining in a moderate or strong intensity.

Results

Of the 146 PT cases reviewed, 110 were classified as benign, 16 as borderline, and 20 as malignant. The correlation between age and size with benign, borderline, and malignant subgroups was statistically significant (p < 0.001). Significance was observed in the expression of both Ki-67 and p53 in the comparison of benign, borderline, and malignant PT with p < 0.001 and a 95% confidence interval (CI). When correlating the presence of positivity in either of the two index tests with the diagnosis of borderline or malignant PT, we reached a sensitivity of 100% and a specificity of 91.8 (p < 0.001; 95% CI).

Conclusion

We propose a practical methodology to achieve an accurate grade of PT, based on clearly defined and easy to apply cutoffs of a simple immunohistochemical panel of Ki-67 and p53. A PT positive for either of the index tests should be graded as borderline or malignant, so pathologists can use this test to improve accuracy. We hope this new approach might provide the basis for the development of standardization in using p53 and Ki-67 for grading PT.

Phyllodes Tumor of the Breast: Histopathologic Features, Differential Diagnosis, and Molecular/Genetic Updates

CONTEXT

-Phyllodes tumor (PT) of the breast is a rare fibroepithelial neoplasm with risks of local recurrence and uncommon metastases. The classification proposed by the World Health Organization for PTs into benign, borderline, and malignant is based on a combination of several histologic features. The differential diagnosis between PT and fibroadenoma and the histologic grading of PT remain challenging. In addition, the molecular pathogenesis of PT is largely unknown.

OBJECTIVE

-To provide an updated overview of pathologic features, diagnostic terminology, and molecular alterations of PT.

DATA SOURCES

-Current English literature related to PT of the breast.

CONCLUSIONS

-Phyllodes tumor shows a wide spectrum of morphology. There are no clearly distinct boundaries between PT and fibroadenoma. Strict histologic assessment of a combination of histologic features with classification can help to achieve the correct diagnosis and provide useful clinical information. The genomic landscapes of PT generated from genomic sequencing provide insights into the molecular pathogenesis of PT and help to improve diagnostic accuracy and identify potential drug targets in malignant PT.

IMP3 Is Strongly Expressed in Malignant Phyllodes Tumors of the Breast

Background. Phyllodes tumors (PTs) of the breast are rare biphasic neoplasms and are classified as benign, borderline, or malignant. Many biological markers have been studied to discriminate between different grades of PTs. IMP3 is a member of the insulin-like growth factor II mRNA binding protein (IMP) family and is expressed in developing tissues during embryogenesis, whereas in adult tissues it is found only at low or undetectable levels. IMP3 is considered a marker of biological aggressiveness in many cancers, including breast and lung. The aim of this study was to evaluate the immunohistochemical expression of IMP3 in a series of PTs and to determine its association with histological grade and clinical outcome. Materials and Methods. We reviewed retrospectively 62 cases of PTs including their recurrences and 20 cases of fibroadenoma. PTs have been classified as benign in 40 cases, borderline in 13 cases, and malignant in 9 cases. Results. There were significant differences in IMP3 expression: in malignant PTs IMP3 expression was higher (56% of cases) than in borderline (15%) and benign cases (5%), ( P = .001). Fibroadenoma showed no expression for IMP3. IMP3 expression was different in cases with recurrence than cases without recurrence. Furthermore, 3 of the recurrences had a higher histological grade with a positive IMP3 expression compared with the primary tumor. Conclusions. This is the first study evaluating the IMP3 immunohistochemical expression in PTs. Its expression correlates with histological grade and could be used in the differential diagnosis of fibroepithelial tumors and in predicting a more aggressive behavior.

CD117 expression in breast phyllodes tumors correlates with adverse pathologic parameters and reduced survival

CD117 (c-kit) is a type III receptor tyrosine kinase encoded by the KIT gene. Deregulation of expression and mutations in the gene are implicated in various tumors. Reports of CD117 expression in phyllodes tumors have been controversial. We aim to investigate the protein expression of CD117 and mutations in the KIT gene in phyllodes tumors, and correlate the findings with pathological parameters and clinical outcome. A total of 272 cases were included in this study. CD117 expression was investigated by immunohistochemistry on tissue microarray sections. Toluidine blue staining was performed to indicate mast cells. Overall, 28 (10%) cases were CD117 positive. CD117 expression was significantly associated with tumor grade (P<0.001), increased stromal hypercellularity (P=0.003), stromal atypia (P=0.01), and stromal mitotic activity (P<0.001), permeative microscopic margins (P=0.002), and presence of hemorrhage (P=0.001). Expression was also associated with poorer overall survival (P=0.003). Nineteen cases were further selected for mutation screening through the Affymetrix OncoScan platform. No mutation of the KIT gene was found. Despite a lack of mutations in the KIT gene, CD117 protein expression is associated with unfavorable pathological parameters and poorer prognosis, suggesting an underlying role in the biology of phyllodes tumors.

Gene expression-based classifications of fibroadenomas and phyllodes tumours of the breast

Fibroepithelial tumors (FTs) of the breast are a heterogeneous group of lesions ranging from fibroadenomas (FAD) to phyllodes tumors (PT) (benign, borderline, malignant). Further understanding of their molecular features and classification might be of clinical value. In this study, we analysed the expression of 105 breast cancer‐related genes, including the 50 genes of the PAM50 intrinsic subtype predictor and 12 genes of the Claudin‐low subtype predictor, in a panel of 75 FTs (34 FADs, 5 juvenile FADs, 20 benign PTs, 5 borderline PTs and 11 malignant PTs) with clinical follow‐up. In addition, we compared the expression profiles of FTs with those of 14 normal breast tissues and 49 primary invasive ductal carcinomas (IDCs). Our results revealed that the levels of expression of all breast cancer‐related genes can discriminate the various groups of FTs, together with normal breast tissues and IDCs (False Discovery Rate < 5%). Among FTs, the levels expression of proliferation‐related genes (e.g. CCNB1 and MKI67) and mesenchymal/epithelial‐related (e.g. CLDN3 and EPCAM) genes were found to be most discriminative. As expected, FADs showed the highest and lowest expression of epithelial‐ and proliferation‐related genes, respectively, whereas malignant PTs showed the opposite expression pattern. Interestingly, the overall profile of benign PTs was found more similar to FADs and normal breast tissues than the rest of tumours, including juvenile FADs. Within the dataset of IDCs and normal breast tissues, the vast majority of FADs, juvenile FADs, benign PTs and borderline PTs were identified as Normal‐like by intrinsic breast cancer subtyping, whereas 7 (63.6%) and 3 (27.3%) malignant PTs were identified as Claudin‐low and Basal‐like, respectively. Finally, we observed that the previously described PAM50 risk of relapse prognostic score better predicted outcome in FTs than the morphological classification, even within PTs‐only. Our results suggest that classification of FTs using gene expression‐based data is feasible and might provide clinically useful biological and prognostic information.

The levels expression of proliferation‐ and mesenchymal/epithelial‐related genes were found to be the most discriminative.

The overall profile of benign phyllodes was very similar to fibroadenomas.

The vast majority of fibroepithelial tumors (FTs) were identified as Normal‐like by the PAM50 and Claudin‐low predictors.

The PAM50 risk of relapse prognostic score better predicted outcome in FTs than the morphological classification.

Classification of FTs using gene expression‐based data provides clinically useful information.

Fibroepithelial tumors of the breast: pathologic and immunohistochemical features and molecular mechanisms

CONTEXT

The 2 main prototypes of fibroepithelial tumors of the breast include fibroadenoma and phyllodes tumor (PT). Although both tumors share some overlapping histologic features, there are significant differences in their clinical behavior and management. Phyllodes tumors have been further divided into clinically relevant subtypes, and there is more than one classification scheme for PT currently in use, suggesting a lack of consistency within different practices. Accurate differentiation between fibroadenoma and PT, as well as the grading of PT, may sometimes be challenging on preoperative core needle biopsy. Some immunohistochemical markers have been suggested to aid in the pathologic classification of these lesions.

OBJECTIVE

To discuss the salient histopathologic features of fibroepithelial tumors and review the molecular pathways proposed for the initiation, progression, and metastasis of PTs. Also, to provide an update on immunohistochemical markers that may be useful in their differential diagnosis and outline the practice and experience at our institution from a pathologic perspective.

DATA SOURCES

Sources included published articles from peer-reviewed journals in PubMed (US National Library of Medicine).

CONCLUSIONS

Fibroepithelial tumor of the breast is a heterogenous group of lesions ranging from fibroadenoma at the benign end of the spectrum to malignant PT. There are overlapping histologic features among various subtypes, and transformation and progression to a more malignant phenotype may also occur. Given the significant clinical differences within various subtypes, accurate pathologic classification is important for appropriate management. Although some immunohistochemical markers may be useful in this differential diagnosis, histomorphology still remains the gold standard.

Utility of Ki-67, CD10, CD34, p53, CD117, and Mast Cell Content in the Differential Diagnosis of Cellular Fibroadenomas and in the Classification of Phyllodes Tumors of the Breast

Adequate management of phyllodes tumors of the breast (PTB) remains a challenge because of the difficulty in correctly establishing preoperative diagnosis. The aim of this study was to evaluate the usefulness of Ki-67, CD10, CD34, p53, CD117, and of the number of mast cells in the differential diagnosis of benign PTB and cellular fibroadenomas (CFs) as well as in the grading of PTB. Fifty-one primary PTB and 14 CFs were examined by immunohistochemistry.When evaluating CD117 expression, higher epithelial expression was present in CF as well as an increased number of mast cells in benign PTB. Stromal expression of Ki-67, CD10, CD34, and p53 were relevant to PTB grading, of which the first 3 showed significance in the distinction of benign and borderline PTB, as well as between benign and malignant PTB. P53 was relevant only for the discrimination between benign and malign PTB. None of the markers showed significance in distinguishing between borderline and malign PTB.

Giant malignant phyllodes tumor: a case report

We present a case of a 57-year-old woman with a giant malignant phyllodes tumor (PT) in her right breast, with maximum diameter of 20 cm. The core-needle and excisional biopsy specimens were diagnosed as suspicious for low-grade myofibroblastic sarcoma (LGMS). The subsequent total mastectomy with partial resection of the pectoral muscles showed predominance of stromal hypercellularity without an epithelial component. However, we diagnosed this as a malignant PT because focal areas showed a leaf-like pattern. In the case of large malignant PTs that exhibit stromal predominance, it can be difficult to distinguish between a pure sarcoma and malignant PT. It is important to thoroughly examine multiple sections from the view point of residual epithelial structure in morphological diagnosis.

CD34, CD117, and Ki-67 Expression in Phyllodes Tumor of the Breast: An Immunohistochemical Study of 33 Cases

Phyllodes tumors (PTs) of the breast are biphasic lesions, comprising an epithelial component set within a neoplastic spindle-celled stroma. These tumors have been classified as benign, borderline, and malignant based on a combination of histological criteria, including stromal cellularity, nuclear pleomorphism, mitotic rate, stromal overgrowth, and margin appearance. The aim of this study was to evaluate the expression of CD34, CD117 (c-kit), and Ki-67 in PT of the breast and attempt to correlate the staining pattern with tumor grade by morphology. Immunohistochemical expression of CD117, CD34, and Ki-67 was studied on formalin-fixed, paraffin-embedded archival tissue material from 33 cases of PT. Histologically, there were 21 benign, 6 borderline, and 6 malignant (high-grade) tumors. All 6 histologically malignant PTs were positive for CD117 (100%), but only 1 marked with CD34 (16.7%). Borderline PTs frequently coexpressed CD34 and CD117 (66.7%). The benign PTs, on the other hand, most commonly (52.4%) showed a CD34(+)/CD117(-) immunoprofile with 33.3% cases coexpressing the markers: that is, CD34(+)/CD117(+). Although most benign PTs (80.6%) showed a Ki-67 of <2%, a few cases showed slightly higher proliferation indices. This study indicates that CD34 and CD117 are differentially expressed in benign and malignant PTs. These markers, therefore, in combination, may be used as an adjunct to morphology in the subclassification of PTs.

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.

Phyllodes tumor of the breast: an update

Phyllodes tumor is an uncommon biphasic breast tumor, with the ability to recur and metastasize, and it behaves biologically like a stromal neoplasm. Traditionally, phyllodes tumors are graded by the use of a set of histologic data into benign, borderline, and malignant. In most series, all phyllodes tumors may recur, but only the borderline and malignant phyllodes tumors metastasize. On the basis of histologic features, prediction of behavior is difficult. The expression of many biological markers, including p53, hormone receptors, proliferation markers, angiogenesis group of markers, c-kit, CD10 and epidermal growth factor receptor have been explored, and many have been shown to be variably expressed, depending on the grade of the tumor. These markers are, however, of limited value in predicting the behavior of the tumor. Recently investigators have reported a plethora of genetic changes in phyllodes tumors, the most consistent of which seems to be 1q gain by comparative genomic hybridization. Some candidate genes have been mapped to various sites, and preliminary data suggest that some of these changes may be related to recurrence. It is foreseeable that more exciting data will be generated to help us to understand the etiology and pathogenesis of phyllodes tumor.

“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.