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

The Investigation of Somatostatin Receptors as a Potential Target in Breast Phyllodes Tumours

BACKGROUND

Somatostatin receptors (SSTRs) are expressed in most neuroendocrine neoplasms, particularly in gastroenteropancreatic neuroendocrine tumours, and have been utilised as diagnostic markers and therapeutic targets. The radioiodinated somatostatin analogue 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid- Tyr3-octreotate (DOTATATE) has been employed for SSTR targeting for either diagnostic or therapeutic purposes depending on the labelling with 68Gallium or 177Lutetium, respectively. SSTR expression is reported in a subset of breast adenocarcinoma and breast neuroendocrine carcinomas; however, minimal knowledge exists regarding their expression in fibroepithelial (biphasic) breast lesions such as fibroadenoma and phyllodes tumours. Aggressive ends of the spectrum, i.e., "cystosarcoma phyllodes", may present a management challenge with recurrences and metastases, and SSTRs could be a promising therapeutic target for these types of tumours.

METHODS

Gene and protein expressions of SSTRs in primary human fibroepithelial lesions of the breast are investigated using RT-PCR and immunoblotting. Localisation of the SSTR-positive cells was determined with immunohistochemistry and immunofluorescence.

RESULTS AND CONCLUSIONS

Both fibroadenoma and phyllodes tumours express SSTRs. Immunohistochemical analyses suggested that this expression is in the stromal, not epithelial, component by demonstrating that SSTR stained in the areas overlapping with α-smooth muscle actin-positive myoepithelial cells around blood vessels and capillary structures. This study is the first in the literature to demonstrate SSTR positivity in mammary fibroepithelial neoplasms. Once validated, these findings may also have significant implications for managing the treatment of these tumours.

The usefulness of evaluating PTEN expression for accurate grading of phyllodes tumors

Phyllodes tumors (PTs) are classified as benign, borderline, or malignant based on histologic characteristics. However, because histological criteria are subjective and diagnosis requires integrating multiple findings, discrepancies often occur between observers. Therefore, it is necessary to discover biomarkers based on the molecular characteristics of PTs. This study aimed to identify dysregulated microRNAs (miRNAs) in PTs through miRNA profiling and determine whether expression of their target genes could be useful as PT biomarkers. MiRNA profiling was performed on 13 PTs (three malignant, three borderline, seven benign) and six fibroadenomas, and predicted target genes of dysregulated miRNAs were selected using three computation algorithms. The expression of two miRNAs, miR-155 and miR-200c, was 1.69-fold and 1.61-fold higher, respectively, in borderline and malignant PT groups than in the benign PT group (p < 0.05). KEGG pathway analysis revealed that the 374 target genes of these two miRNAs (miR-155 and miR200c) participated in several signaling pathways, adherens junction, cell cycle, and pathway in cancer. Immunohistochemical staining for PTEN, one of candidate target genes of miR-200c, was performed on whole slides of PT tissue classified as malignant (n = 9), borderline (n = 12), or benign (n = 21). Stromal tumor cells of high-grade PTs (borderline and malignant) had significantly lower PTEN expression than those of low-grade PTs (benign) (p-value ≤0.001). Semiquantitative analysis of PTEN expression, score 0-8, revealed that it correlated with histologic findings. Low PTEN expression (s-score of 6 or less) was used as a diagnostic criterion for high-grade PTs, it showed 100 % sensitivity and 95.2 % specificity in 42 cases of PTs. Currently, PT grading based solely on subjective histologic findings is challenging, but semiquantitative PTEN expression analysis could provide a more accurate and objective way to grade PTs.

Deep learning-assisted distinguishing breast phyllodes tumours from fibroadenomas based on ultrasound images: a diagnostic study

OBJECTIVES

To evaluate the performance of ultrasound-based deep learning (DL) models in distinguishing breast phyllodes tumours (PTs) from fibroadenomas (FAs) and their clinical utility in assisting radiologists with varying diagnostic experiences.

METHODS

We retrospectively collected 1180 ultrasound images from 539 patients (247 PTs and 292 FAs). Five DL network models with different structures were trained and validated using nodule regions annotated by radiologists on breast ultrasound images. DL models were trained using the methods of transfer learning and 3-fold cross-validation. The model demonstrated the best evaluation index in the 3-fold cross-validation was selected for comparison with radiologists' diagnostic decisions. Two-round reader studies were conducted to investigate the value of DL model in assisting 6 radiologists with different levels of experience.

RESULTS

Upon testing, Xception model demonstrated the best diagnostic performance (area under the receiver-operating characteristic curve: 0.87; 95% CI, 0.81-0.92), outperforming all radiologists (all P < .05). Additionally, the DL model enhanced the diagnostic performance of radiologists. Accuracy demonstrated improvements of 4%, 4%, and 3% for senior, intermediate, and junior radiologists, respectively.

CONCLUSIONS

The DL models showed superior predictive abilities compared to experienced radiologists in distinguishing breast PTs from FAs. Utilizing the model led to improved efficiency and diagnostic performance for radiologists with different levels of experience (6-25 years of work).

ADVANCES IN KNOWLEDGE

We developed and validated a DL model based on the largest available dataset to assist in diagnosing PTs. This model has the potential to allow radiologists to discriminate 2 types of breast tumours which are challenging to identify with precision and accuracy, and subsequently to make more informed decisions about surgical plans.

Histopathological Downgrading of Borderline Phyllodes Tumor in a Young Patient Following Chemotherapy: A Case Report

Phyllodes tumors (PT) are fibroepithelial neoplasms that are treated by complete surgical excision. The effectiveness of adjuvant therapies, including radiotherapy and chemotherapy, for PT remains unclear, and the use of neoadjuvant chemotherapy (NAC) is yet to be established. We report a case of a 15-year-old girl with acute lymphatic leukemia (ALL) who was incidentally diagnosed with a 50-mm borderline PT in the left breast using computed tomography, ultrasonography, and histological examination following needle biopsy. Lumpectomy was performed after administration of anthracycline-based chemotherapy for ALL, resulting in tumor size reduction. Histopathological examination of the excised specimen demonstrated decreased mitotic activity and stromal cellularity post-chemotherapy. To our knowledge, this is the first study to report the histopathological differences in pre- and post-chemotherapy borderline PT samples. Our findings suggest that NAC may induce changes in borderline PT, potentially affecting diagnosis and treatment decisions. Hence, further investigation is warranted in this regard.

Precise diagnosis of breast phyllodes tumors using Raman spectroscopy: Biochemical fingerprint, tumor metabolism and possible mechanism

BACKGROUND

Breast fibroadenomas and phyllodes tumors are both fibroepithelial tumors with comparable histological characteristics. However, rapid and precise differential diagnosis is a tough point in clinical pathology. Given the tendency of phyllodes tumors to recur, the difficulty in differential diagnosis with fibroadenomas leads to the difficulty in optimal management for these patients.

METHOD

In this study, we used Raman spectroscopy to differentiate phyllodes tumors from breast fibroadenomas based on the biochemical and metabolic composition and develop a classification model. The model was validated by 5-fold cross-validation in the training set and tested in an independent test set. The potential metabolic differences between the two types of tumors observed in Raman spectroscopy were confirmed by targeted metabolomic analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS).

RESULTS

A total of 204 patients with formalin-fixed paraffin-embedded (FFPE) tissue samples, including 100 fibroadenomas and 104 phyllodes tumors were recruited from April 2014 to August 2021. All patients were randomly divided into the training cohort (n = 153) and the test cohort (n = 51). The Raman classification model could differentiate phyllodes tumor versus fibroadenoma with cross-validation accuracy, sensitivity, precision, and area under curve (AUC) of 85.58 % ± 1.77 %, 83.82 % ± 1.01 %, 87.65 % ± 4.22 %, and 93.18 % ± 1.98 %, respectively. When tested in the independent test set, it performed well with the test accuracy, sensitivity, specificity, and AUC of 83.50 %, 86.54 %, 80.39 %, and 90.71 %. Furthermore, the AUC was significantly higher for the Raman model than that for ultrasound (P = 0.0017) and frozen section diagnosis (P < 0.0001). When it came to much more difficult diagnosis between fibroadenoma and benign or small-size phyllodes tumor for pathological examination, the Raman model was capable of differentiating with AUC up to 97.45 % and 95.61 %, respectively. On the other hand, targeted metabolomic analysis, based on fresh-frozen tissue samples, confirmed the differential metabolites (including thymine, dihydrothymine, trans-4-hydroxy-l-proline, etc.) identified from Raman spectra between phyllodes tumor and fibroadenoma.

SIGNIFICANCE AND NOVELTY

In this study, we obtained the molecular information map of breast phyllodes tumors provided by Raman spectroscopy for the first time. We identified a novel Raman fingerprint signature with the potential to precisely characterize and distinguish phyllodes tumors from fibroadenoma as a quick and accurate diagnostic tool. Raman spectroscopy is expected to further guide the precise diagnosis and optimal treatment of breast fibroepithelial tumors in the future.

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.

Single cell profiling of female breast fibroadenoma reveals distinct epithelial cell compositions and therapeutic targets

Fibroadenomas (FAs) are the most common breast tumors in women. No pharmacological agents are currently approved for FA intervention owing to its unclear mechanisms and a shortage of reproducible human models. Here, using single-cell RNA sequencing of human FAs and normal breast tissues, we observe distinct cellular composition and epithelial structural changes in FAs. Interestingly, epithelial cells exhibit hormone-responsive functional signatures and synchronous activation of estrogen-sensitive and hormone-resistant mechanisms (ERBB2, BCL2 and CCND1 pathways). We develop a human expandable FA organoid system and observe that most organoids seem to be resistant to tamoxifen. Individualized combinations of tamoxifen with ERBB2, BCL2 or CCND1 inhibitors could significantly suppress the viability of tamoxifen-resistant organoids. Thus, our study presents an overview of human FA at single-cell resolution that outlines the structural and functional differences between FA and normal breast epithelium and, in particular, provides a potential therapeutic strategy for breast FAs.

Differentiation between Phyllodes Tumors and Fibroadenomas through Breast Ultrasound: Deep-Learning Model Outperforms Ultrasound Physicians

The preoperative differentiation of breast phyllodes tumors (PTs) from fibroadenomas (FAs) plays a critical role in identifying an appropriate surgical treatment. Although several imaging modalities are available, reliable differentiation between PT and FA remains a great challenge for radiologists in clinical work. Artificial intelligence (AI)-assisted diagnosis has shown promise in distinguishing PT from FA. However, a very small sample size was adopted in previous studies. In this work, we retrospectively enrolled 656 breast tumors (372 FAs and 284 PTs) with 1945 ultrasound images in total. Two experienced ultrasound physicians independently evaluated the ultrasound images. Meanwhile, three deep-learning models (i.e., ResNet, VGG, and GoogLeNet) were applied to classify FAs and PTs. The robustness of the models was evaluated by fivefold cross validation. The performance of each model was assessed by using the receiver operating characteristic (ROC) curve. The area under the curve (AUC), accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were also calculated. Among the three models, the ResNet model yielded the highest AUC value, of 0.91, with an accuracy value of 95.3%, a sensitivity value of 96.2%, and a specificity value of 94.7% in the testing data set. In contrast, the two physicians yielded an average AUC value of 0.69, an accuracy value of 70.7%, a sensitivity value of 54.4%, and a specificity value of 53.2%. Our findings indicate that the diagnostic performance of deep learning is better than that of physicians in the distinction of PTs from FAs. This further suggests that AI is a valuable tool for aiding clinical diagnosis, thereby advancing precision therapy.

Gene Expression Profiling of Fibroepithelial Lesions of the Breast

Fibroepithelial lesions of the breast (FELs) are a heterogeneous group of neoplasms exhibiting a histologic spectrum ranging from fibroadenomas (FAs) to malignant phyllodes tumors (PTs). Despite published histologic criteria for their classification, it is common for such lesions to exhibit overlapping features, leading to subjective interpretation and interobserver disagreements in histologic diagnosis. Therefore, there is a need for a more objective diagnostic modality to aid in the accurate classification of these lesions and to guide appropriate clinical management. In this study, the expression of 750 tumor-related genes was measured in a cohort of 34 FELs (5 FAs, 9 cellular FAs, 9 benign PTs, 7 borderline PTs, and 4 malignant PTs). Differentially expressed gene analysis, gene set analysis, pathway analysis, and cell type analysis were performed. Genes involved in matrix remodeling and metastasis (e.g., MMP9, SPP1, COL11A1), angiogenesis (VEGFA, ITGAV, NFIL3, FDFR1, CCND2), hypoxia (ENO1, HK1, CYBB, HK2), metabolic stress (e.g., UBE2C, CDKN2A, FBP1), cell proliferation (e.g., CENPF, CCNB1), and the PI3K-Akt pathway (e.g., ITGB3, NRAS) were highly expressed in malignant PTs and less expressed in borderline PTs, benign PTs, cellular FAs, and FAs. The overall gene expression profiles of benign PTs, cellular FAs, and FAs were very similar. Although a slight difference was observed between borderline and benign PTs, a higher degree of difference was observed between borderline and malignant PTs. Additionally, the macrophage cell abundance scores and CCL5 were significantly higher in malignant PTs compared with all other groups. Our results suggest that the gene-expression-profiling-based approach could lead to further stratification of FELs and may provide clinically useful biological and pathophysiological information to improve the existing histologic diagnostic algorithm.

The largest and heaviest giant juvenile fibroadenoma of the breast in the Chinese population: A case report

RATIONALE

Fibroadenoma is the most common benign tumor of the breast, but giant juvenile fibroadenoma exceeding 20 cm is much rare. This report presents the largest and heaviest giant juvenile fibroadenoma in an 18-year-old Chinese girl.

DIAGNOSIS AND INTERVENTIONS

An 18-year-old adolescent girl with a 2-year history of a large left breast mass with progressive expansion over 11 months. A 28 × 21 cm soft swelling occupied the entire outer quadrants of the left breast. The huge mass sagged below the belly button, resulting in high asymmetry of the shoulders. Contralateral breast examination results were normal except for hypopigmentary detected on the nipple-areola complex. Under general anesthesia, the lump was completely excised along the outer envelope of the tumor, while reserving excessive resection of the skin. The patient's postoperative recovery was uneventful, and the surgical wound healed well.

OUTCOMES

A radial incision operation was finally performed to remove the huge mass and to preserve the normal breast tissue and the nipple-areolar complex, not only considering the aesthetics but also preserving the ability to lactate.

LESSONS

Currently, there is a lack of clear guidelines regarding the diagnostic and treatment modalities for a giant juvenile fibroadenoma. The principle of surgical choice is to balance aesthetics and function preservation.

Fibroepithelial lesions of the breast: improving the accuracy of imaging diagnosis and reducing unnecessary biopsy

Fibroadenomas and phyllodes tumours are fibroepithelial lesions of the breast. Fibroadenomas are common benign breast masses encountered both symptomatically and incidentally. Phyllodes tumours are uncommon and usually present symptomatically. Management of fibroadenomas focuses on reducing biopsies without missing cancers while radiological management of phyllodes tumours should focus on predicting the need for surgical excision with or without margins.

Fibroadenoma of the breast; incidence of malignancy and indicators for surgical intervention: An analysis of 1392 patients

BACKGROUND

Fibroadenomas are common among young females. The size of the lesion used to be an indication for further assessment or excision. With arising of the watch and see proponents, criteria for selecting patients are important to establish.

METHODS

This is a retrospective study of a prospectively maintained database where all patients having the clinical/radiological provisional diagnosis of fibroadenoma and attending our center - from January 2008 to March 2020 - were enrolled. The primary outcome was the incidence of malignancy and the secondary outcomes were the correlation of malignancy-risk with epidemiologic and radiologic criteria.

RESULTS

The study enrolled 1392 patients. The mean age of the patients was 35.7 + ∕- 13.1 years. The median of the longest diameter of the detected breast lesions was 25 mm. The incidence of malignancy was 188 (13.5%). The size of the lesion measured by largest diameter was insignificant (p = 0.99), while the patients' age, marital status, and imaging criteria as measured by BIRADS score were significant (<0.001).

CONCLUSION

Approaching patients with the age above 35 or with BIRADS 4 provisionally diagnosed with fibroadenomas should be cautious with biopsy and short-term follow-ups The size of the tumor alone should not be used as an indication for surgical intervention.

Transformation of a Benign-Appearing Fibroepithelial Lesion to a Giant Malignant Phyllodes Tumor of the Breast

This is a case of a woman who presented with a left breast mass that was initially diagnosed as fibroadenoma on core biopsy and, after three years without any surgical intervention, was found to be a malignant phyllodes tumor. Initially, a core needle biopsy of the mass showed probable fibroadenoma. Because of the initial benign seeming diagnosis and the need to treat her tongue cancer, the patient did not recognize the need for a recommended surgical consultation and excision. Three years later, she presented after the mass had enlarged to encompass nearly the whole left breast. Core needle biopsy revealed spindle cell proliferation with scattered benign-looking tubules. Due to the large size of the mass, she underwent a total mastectomy, and the final pathology demonstrated a malignant phyllodes tumor. This case demonstrates a case of progression of a benign-appearing fibroepithelial lesion to a malignant phyllodes tumor three years later.

An integrative ultrasound-pathology approach to improve preoperative phyllodes tumor classification: A pilot study

OBJECTIVE

Preoperative diagnosis of phyllodes tumor (PT) is challenging, core-needle biopsy (CNB) has a significant rate of understaging, resulting in suboptimal surgical planification. We hypothesized that the association of imaging data to CNB would improve preoperative diagnostic accuracy compared to biopsy alone.

METHODS

In this retrospective pilot study, we included 59 phyllodes tumor with available preoperative imaging, CNB and surgical specimen pathology.

RESULTS

Two ultrasound features: tumor heterogeneity and tumor shape were associated with tumor grade, independently of CNB results. Using a machine learning classifier, the association of ultrasound features with CNB results improved accuracy of preoperative tumor classification up to 84%.

CONCLUSION

An integrative approach of preoperative diagnosis, associating ultrasound features and CNB, improves preoperative diagnosis and could thus optimize surgical planification.

MED12 exon 2 and TERT promoter mutations in primary and recurrent breast fibroepithelial lesions

The genetic alterations in the recurrent breast fibroepithelial tumors are poorly understood. In the present study, we aimed to investigate mediator protein complex subunit 12 (MED12) exon 2 and telomerase reverse transcriptase (TERT) promoter mutations in a series of primary and recurrent fibroepithelial tumors. Sanger sequencing for MED12 exon 2 and TERT promoter was performed in 26 pairs of primary and recurrent fibroepithelial tumors (19 pairs of phyllodes tumors and seven pairs of fibroadenomas). The relationship between the genotypes and clinicopathological variables was also analyzed. MED12 mutation was identified in 19 primary tumors (12 phyllodes tumors and 7 fibroadenomas) and 17 recurrences (14 phyllodes tumors and three fibroadenomas). Most recurrent phyllodes tumors retained the original MED12 variants (17/19). Six recurrent fibroadenomas showed different MED12 variants from their paired primary tumors (6/7). TERT promoter mutation was identified in 13 primary phyllodes tumors (13/19) and 15 recurrent phyllodes tumors (15/19). However, it was only identified in one primary fibroadenoma (1/7). Recurrent phyllodes tumors often retained the original MED12 and TERT promoter mutations, while recurrent fibroadenomas often acquired new MED12 mutations. Our findings suggest that recurrent phyllodes tumors may be "true recurrence," and TERT mutant "benign fibroepithelial tumors" should be treated as phyllodes tumors.

A Diagnostic Enigma - A Rare Presentation Of Juvenile Fibroadenoma In A Premenarchal Girl

AIM

Reporting a rare case of a teenage girl, with a bizarre clinical presentation of a benign breast condition, that too is uncommon at her age.

CASE

A 14-year-old pre-menarche girl presented with a rapidly progressing lump that involved the entire breast within 3 months. It was associated with ulceration of the overlying skin along with destruction of the nipple-areola complex.

RESULTS

During the pre- operative workup, a neoplastic etiology was suspected, but post- operative histopathology revealed it to be giant juvenile fibroadenoma.

CONCLUSION

This case emphasizes on the benign character of breast masses in the adolescent age group. Despite the massive volume and appearance, the opportunity of a conservative surgical approach should be sought.

Expression of lymphoid enhancer-binding factor 1 in breast fibroepithelial lesions

Phyllodes tumors (PTs) are rare epithelial-mesenchymal tumors of the breast with malignant potential. Here, we evaluate the nuclear expression of lymphoid enhancer-binding factor 1 (LEF-1), a transcription factor downstream of Wnt/β-catenin signaling, in fibroepithelial lesions of the breast. Excised fibroepithelial lesions of the breast were retrospectively reviewed, blinded to the original diagnosis, and classified according to World Health Organization (WHO) criteria. A tissue microarray (TMA) was composed with two representative cores from each case, including 24 benign lesions, 11 borderline phyllodes, and 8 malignant PTs. β-Catenin, LEF-1, p120, and E-cadherin immunohistochemistry was performed on the TMA, and staining was quantified. The malignant/borderline PTs showed higher stromal LEF-1 expression than benign tumors (P < 0.001). Stromal cells expressed LEF-1 in 100% (16/16 of core TMA) of malignant phyllodes, compared with 73% (16/22) borderline and 27% (13/48) benign tumors. The average LEF-1 H-score was 24.9, 6.1, and 1.5 for malignant, borderline, and benign tumors, respectively. Nuclear expression of β-catenin in the stromal component was more often seen in malignant than in borderline and benign tumors (44% versus 32% and 23%, respectively). Nine TMA cores of malignant tumors without nuclear β-catenin staining demonstrated LEF-1 expression. Both LEF-1 and nuclear β-catenin showed expression in the majority of borderline/malignant PTs suggesting a biological progression of Wnt/β-catenin pathway activation in the stromal component from benign to malignant tumors. Inhibitors for the Wnt/β-catenin pathway may provide alternative treatment options in the future for malignant or metastatic PTs.