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.     

Frequency of MED12 mutations in phyllodes tumors: Inverse correlation with histologic grade

Phyllodes tumor (PT) is a rare breast biphasic tumor with a potential risk of recurrence and metastasis. In this study, the frequency of MED12 mutations in 176 PTs (49 benign, 49 borderline, and 78 malignant) was determined and the prognostic effect of these mutations in malignant type PT was evaluated. Analysis of MED12 mutations was performed by Sanger sequencing targeting the hotspot mutation region (exon 2) of MED12. Immunohistochemistry was also applied for evaluation of MED12 protein expression on tissue microarray blocks for 133 PTs including 50 benign, 50 borderline, and 33 malignant cases. A notable difference in the frequency of MED12 mutations was found according to histologic grade (71.4% of benign PTs, 51% of borderline PTs, 26.9% of malignant PTs; P < 0.001). MED12 protein expression was not correlated with MED12 mutation status. Patients with malignant PTs that harbored MED12 mutations demonstrated improved disease‐free survival (DFS) compared with those without MED12 mutation (P = 0.07). MED12 mutation was a common molecular alteration in PT and the frequency of MED12 mutation decreased with increasing histologic grade. In malignant PT, MED12 exon 2 mutations showed improved DFS but without significance. © 2016 Wiley Periodicals, Inc.     

mRNA expression profiling of phyllodes tumours of the breast: identification of genes important in the development of borderline and malignant phyllodes tumours

The aim of this study was to identify genes involved in the development of borderline and malignant phyllodes tumours of the breast (PTs). Expression profiling of 23 PTs (12 benign, 11 borderline/malignant) was performed using Affymetrix U133A GeneChips. mRNA expression in the borderline/malignant PTs was compared to the benign PTs. A group of 162 genes was over-expressed in the borderline/malignant group with a fold change > 2 and FDR < 0.1. Four of these genes were chosen for further investigation: PAX3, SIX1, TGFB2 and HMGA2. Over-expression was validated in a separate set of formalin-fixed, paraffin-embedded (FFPE) tumours, using either in situ hybridization or immunohistochemistry. This confirmed that expression of PAX3, SIX1, TGFB2 and HMGA2 in the stromal component of PTs was associated with the borderline/malignant phenotypes (p = 8.7 x 10(-5), p = 0.05, p = 0.009, p = 0.003, respectively; Fisher's exact test). The functional consequences of down-regulating these genes were studied using siRNA in short-term cultures and cell lines established from PTs. mRNA 'knock-down' of PAX3 resulted in significantly decreased cell proliferation in both a malignant and a borderline PT cell culture. mRNA 'knock-down' of SIX1 and HMGA2 resulted in decreased cell proliferation only in the malignant PT cell line, and 'knock-down' of TGFB2 resulted in decreased cell proliferation only in the borderline PT cell culture. This study shows that these four genes are involved in the development of borderline/malignant PTs. SIX1 over-expression was most marked in the highly malignant PTs, with particularly high expression in one case of metastatic PT. PAX3, TGFB2 and HMGA2 were expressed predominantly in borderline/malignant PTs, but showed some expression in benign tumours; they may be important in the transition from the benign to borderline/malignant phenotype.     

CD10, actin, and vimentin expression in breast phyllodes tumors correlates with tumor grades of the WHO grading system

The discrimination of borderline from malignant primary breast phyllodes (PT) tumor is still unclear. We studied 22 PT cases to investigate the immunohistochemical expression (staining of stromal CD10, SMA [smooth muscle actin], and vimentin) as well as the features of focal glandular atypia to determine whether these correlated with the histopathologic grading system. In our results, the stromal staining of CD10 was positive in 4 of 6 malignant and 2 of 5 borderline PT cases, but negative in all benign PT cases. Stromal actin and intraglandular vimentin-expressive tumor cells were found in 5 of 6 malignant PT cases but not in borderline and benign PT cases. There is a significant difference in the panel of stromal CD10, actin, and vimentin expression between borderline and malignant PT (p<0.05). Besides, the progression of malignant potential breast phyllodes tumor may cause glandular epithelium atypia with loss of polarity.     

Ubiquitin carboxy-terminal hydrolase L1 may be involved in the development of mammary phyllodes tumors

Phyllodes tumors (PTs) are characterized by co-proliferation of the stroma and epithelium, with the stroma being the neoplastic element. Ubiquitin carboxy-terminal hydrolase L1 (UCHL1) is a deubiquitinating enzyme that was originally considered to be a neuronal-specific marker, but later reports have shown both tumorigenic and antitumorigenic roles for UCHL1. Although a role for UCHL1 has been explored in many cancers, a study on PTs has never been reported. We assessed UCHL1 expression in 49 cases of PTs and 16 fibroadenomas using immunohistochemistry and examined associations with clinicopathological features. In normal breast, strong staining for UCHL1 was consistently observed in the nerve bundles, if present, in breast stroma. Scattered stromal cells showed negative to weak staining. The ductal and lobular units, in contrast, showed no staining. In contrast to the 16 fibroadenomas, of which only 3 showed mild staining, UCHL1 expression was consistently observed in all 49 PTs. There was a significantly increasing trend of UCHL1 expression with increasing PT grade (P?<?0.001); strong staining was observed in 24 % of benign PTs, but was present in 56 and 90 % of borderline and malignant PTs, respectively. Consistently, UCHL1 was focally positive in regions of benign to borderline malignancy, but strongly and diffusely immunoreactive in regions of malignancy in cases of malignant PTs. In addition to PT grade, UCHL1 expression correlated with increasing stromal atypia (P?=?0.01), but not with other clinicopathological parameters. In conclusion, the consistent expression of UCHL1 in PTs and an increasing trend of UCHL1 expression with an increasing PT grade suggest a role for UCHL1 in the pathogenesis and malignant progression of PTs.     

Detailed DNA methylation characterisation of phyllodes tumours identifies a signature of malignancy and distinguishes phyllodes from metaplastic breast carcinoma

Phyllodes tumours (PTs) are rare fibroepithelial lesions of the breast that are classified as benign, borderline, or malignant. As little is known about the molecular underpinnings of PTs, current diagnosis relies on histological examination. However, accurate classification is often difficult, particularly for distinguishing borderline from malignant PTs. Furthermore, PTs can be misdiagnosed as other tumour types with shared histological features, such as fibroadenoma and metaplastic breast cancers. As DNA methylation is a recognised hallmark of many cancers, we hypothesised that DNA methylation could provide novel biomarkers for diagnosis and tumour stratification in PTs, whilst also allowing insight into the molecular aetiology of this otherwise understudied tumour. We generated whole-genome methylation data using the Illumina EPIC microarray in a novel PT cohort (n = 33) and curated methylation microarray data from published datasets including PTs and other potentially histopathologically similar tumours (total n = 817 samples). Analyses revealed that PTs have a unique methylome compared to normal breast tissue and to potentially histopathologically similar tumours (metaplastic breast cancer, fibroadenoma and sarcomas), with PT-specific methylation changes enriched in gene sets involved in KRAS signalling and epithelial-mesenchymal transition. Next, we identified 53 differentially methylated regions (DMRs) (false discovery rate < 0.05) that specifically delineated malignant from non-malignant PTs. The top DMR in both discovery and validation cohorts was hypermethylation at the HSD17B8 CpG island promoter. Matched PT single-cell expression data showed that HSD17B8 had minimal expression in fibroblast (putative tumour) cells. Finally, we created a methylation classifier to distinguish PTs from metaplastic breast cancer samples, where we revealed a likely misdiagnosis for two TCGA metaplastic breast cancer samples. In conclusion, DNA methylation alterations are associated with PT histopathology and hold the potential to improve our understanding of PT molecular aetiology, diagnostics, and risk stratification. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.     

Phyllodes tumor of the breast clinical experience and outcomes: A retrospective cohort tertiary hospital experience

BackgroundPhyllodes tumor (PT) accounts for <1% of all breast tumors worldwide. Based on their microscopic features, these tumors are classified into benign, borderline, and malignant. This study aimed at evaluating the clinical experience and the clinicopathologic features of PT.MethodsA retrospective cohort study of 46 female patients with histologically diagnosed PT. Data collection and evaluation was done on patient demographics, preoperative radiological assessment and pathology, surgical procedure, post-surgery pathological evaluation, radiation therapy (RT), and follow-up.ResultsThe median age at diagnosis was 42 years and young premenopausal patients (median age 35 years) had malignant PT. Forty-five patients underwent core needle biopsy (CNB) with high sensitivity and the positive predictive value (82.2% and 97.4% respectively). Thirty-nine patients (86.7%) underwent conservative surgery and 6 (13.3%) had a mastectomy. Twenty-seven (58.6%) were classified as benign, 11 (23.9%) as borderline and only 8 (17.4%) as malignant PT. Malignant PT had the greatest median tumor size (13 cm). Mortality and recurrence rates were 4.3% and 2.2% respectively. RT was administered in 6 patients (13.0%), 5 having malignant and 1 borderline PT. The metastatic rate was found to be 6.5%.ConclusionPT are rare breast tumors with variable biologic behavior and heterogenous clinicopathological findings. Young, premenopausal women with large tumors may have malignant PT with a risk of recurrence and metastasis. Core needle biopsy is a reliable tool for diagnosis of PT with strict follow-up recommended for large tumors diagnosed as fibroadenoma on CNB. Surgical management must ensure a tumor-free margin on excision to reduce recurrence.     

Differential pattern of perivascular type IV collagen deposits in phyllodes tumors of the breast.

Deposition of basement membrane extracellular matrix is influenced by adjacent tumor cells, and in some cases, the pattern of type IV collagen deposit is characteristic in malignant tumors. In this report, we analyzed the difference in type IV collagen deposition patterns between benign and malignant phyllodes tumors (PTs) of the breast. Of the 15 cases of PTs, 8 cases were benign PTs and 7 cases were malignant PTs. Three cases of other primary sarcomas of the breast (stromal sarcoma, angiosarcoma and osteosarcoma) and 2 cases of fibroadenomas were studied for comparison. The malignant PTs were distinguished from benign ones by increased mitotic figures, cellular atypism, and a higher proliferation index of stromal cells. Immunohistochemical staining against type IV collagen in malignant PTs revealed extensive to moderate deposition of type IV collagen around the small blood vessels in duplicate or multilayering pattern, while benign PTs showed minimal deposition in a single linear pattern. All of the three cases of other sarcomas revealed multilayering or meshwork pattern of type IV collagen around the blood vessels. The deposition of type IV collagen around the blood vessels may reflect the malignant behavior of the stromal tumors of the breast.     

Fine-needle aspiration cytology of phyllodes tumors

Breast lesions with a significant spindle cell or mesenchymal component are not commonly encountered in fine-needle aspiration (FNA) cytologic material and include a heterologous variety of benign and malignant conditions, with phyllodes tumors (PTs) being the foremost differential diagnostic consideration. This study comprises 28 tumors diagnosed histologically as PT in which FNAC material was available for review. Histological sections and cytological smears from these cases were retrieved and subjected to detailed morphological review. Cytological parameters assessed included ratio of stroma to epithelium, pattern characteristics and cytological characteristics of the stromal, and epithelial components and the background cells. Large and hypercellular stroma fragments, dissociated spindle and plump stromal cells, often accompanied by large, folded sheets of epithelium were cytological features that characterized PT. Smears from malignant PT showed predominantly or solely mesenchymal components. FNAC was a highly reliable procedure for the diagnosis of PT, giving an accuracy rate of 92.8%.     

Borderline and malignant phyllodes tumors display similar promoter methylation profiles

Mammary phyllodes tumors (PTs) are uncommon fibroepithelial neoplasms. On the basis of histologic criteria, PTs can be divided into benign, borderline, and malignant groups; however, the histologic distinction of PTs is often difficult and arbitrary. In breast cancer, promoter hypermethylation is a common phenomenon, but there are no data available concerning methylation status in PTs. The aim of this study was to assess whether the methylation profiles support the classification of PTs into three subgroups. A multiplex, nested, methylation-specific polymerase chain reaction approach was used to examine promoter methylation of five genes (GSTP1, HIN-1, RAR-β, RASSF1A, and Twist) in 87 PTs (54 benign, 23 borderline, and 10 malignant). Immunohistochemical staining for GSTP1 was performed using tissue microarray blocks to determine whether GSTP1 promoter hypermethylation correlated with loss of GSTP1 expression. There was a trend of increasing methylation frequency with increasing grade of PTs. The methylation frequency of all genes and the mean number of methylated genes in borderline and malignant PTs were higher than those in benign PTs; however, there were no statistically significant differences between borderline and malignant PTs. GSTP1 promoter hypermethylation was associated with loss of GSTP1 expression (p < 0.001). These results suggest that PTs segregate into only two groups on the basis of their methylation profiles: the benign group and the combined borderline/malignant group.     

Lipogranuloma with osseous metaplasia in the breast that developed after "Bu-Hwang" oriental medicine treatment

A lipogranuloma is an inflammatory reactive process associated with exogenous or endogenous lipids, and it's occurrence in the breast has rarely been reported. Osseous metaplasia, which is used to describe bone formation in abnormal locations, can develop from several conditions such as trauma or a tumor. However, few studies have reported benign breast lesions that have been seen as osseous metaplasia. We present a case of a benign calcified breast lesion that developed after a traumatic treatment process called "Bu-Hwang", and it was confirmed as a lipogranuloma with osseous metaplasia. To the best of our knowledge, this is the first reported case of a lipogranuloma with osseous metaplasia in the breast.     

A comprehensive genetic profile of phyllodes tumours of the breast detects important mutations, intra-tumoral genetic heterogeneity and new genetic changes on recurrence

The aims of this study were to identify genetic changes associated with malignant progression of the fibroepithelial neoplasms, phyllodes tumours of the breast (PTs), and to ascertain whether genetic progression occurs when PTs recur locally. A further aim was to assess whether the genetic data support the classification of these tumours into three subtypes, benign, borderline and malignant. 126 PTs (37 benign, 41 borderline, 48 malignant) were analysed by either array-CGH or the Illumina Goldengate assay. The large-scale genetic changes associated with malignant/borderline phenotypes were +1q, +5p, +7, +8, -6, -9p, -10p and -13. Cluster analysis of the array-CGH data supported the division of malignant and borderline PTs into two separate groups, one comprising almost all malignant lesions and the other, benign and borderline tumours. Interstitial deletions of 9p21 that involved the p16INK4a locus were present in many malignant/borderline PTs, and some of these appeared to cause homozygous loss. Loss of expression of p16INK4a was found frequently and this was associated with 9p deletion; we also identified one p16INK4a mutation and evidence of methylation of p16INK4a in malignant PTs. Our evidence shows that inactivation of this gene is important in the development of malignant PTs. In selected PTs, multiple areas of stroma were isolated and analysed separately by array-CGH. We found considerable intra-tumoral genetic heterogeneity. Analysis of paired primary and recurrent tumours showed that recurrent tumours often acquired new genetic changes; in particular, benign tumours tended to acquire changes characteristic of the malignant/borderline phenotype. We believe it likely that unfavourable sub-clones not easily identified by histology account for the unpredictable clinical behaviour of these tumours.     

Localized primary amyloid tumor associated with osseous metaplasia presenting as bilateral breast masses: Cytologic and radiologic features

This report details the cytologic features of primary localized amyloid tumor of the breast presenting as bilateral breast masses in a 72-yr-old woman. Clinically and radiographically, the masses simulated metastatic or multifocal carcinoma. Fine-needle aspiration revealed irregular globules of acellular amorphous material and numerous multinucleated giant cells resembling granulomatous inflammation. Histology confirmed amyloid tumors with a foreign-body giant cell reaction in response to amyloid and foci of osseous metaplasia. Subsequent clinical workup included a serum electrophoresis and immunofixation which showed a small IgG k monoclonal protein. Urine immunofixation was negative for Bence Jones protein. Bone marrow examination revealed no evidence of a plasma cell dyscrasia. To date the patient has not developed clinical or laboratory evidence of systemic amyloidosis or multiple myeloma. Amyloidosis involving the breast and specifically localized primary amyloid tumors of the breast are rare and infrequently reported entities. To our knowledge, osseous metaplasia within isolated primary amyloid tumors of the breast has not been reported. We present this unusual case to illustrate the intratumoral calcification patterns mimicking carcinoma and to characterize the cytologic features. Emphasis is placed on the inclusion of amyloidosis in the differential diagnosis of breast masses.     

Development of mouse models of malignant phyllodes tumors by transplantation of syngeneic mammary gland cells expressing mutant H‐Ras

Phyllodes tumors (PTs) are rare fibroepithelial tumors of the breast with epithelial and stromal components, and surgical resection is the standard and only available treatment for malignant PTs. To provide a better understanding of these tumors, we developed mouse models that recapitulate the pathological and clinical properties of human malignant PTs. Mouse undifferentiated mammary gland cells were infected with a retrovirus encoding the human oncoprotein H‐Ras^G12V, and the infected cells were transplanted orthotopically into the mammary fat pads of syngeneic mice. The transplanted cells showed a high tumorigenic activity, with the resulting tumors manifesting pathological characteristics including stromal overgrowth similar to those of human malignant PTs. The tumors also showed high rates of both local recurrence and lung metastasis. Our models may prove useful for studies of the pathophysiology of malignant PTs as well as facilitate the development of new treatments.     

Fine-needle aspiration of a metaplastic breast carcinoma with extensive melanocytic differentiation: a case report

Metaplastic carcinomas of the breast are uncommon breast tumors with aberrant cellular differentiation, most commonly showing ductal, squamous, and mesenchymal components. A breast carcinoma composed of both epithelial and melanocytic differentiation is rare, with only four previously reported cases in the literature. We present the fifth reported case, where the diagnosis was suggested by fine-needle aspiration (FNA) and later confirmed after the surgical specimen was excised. Histologically, this neoplasm revealed multidirectional differentiation, consisting primarily of squamous and melanocytic cell types, with focal glandular and osseous metaplasia. Based on the morphologic, immunohistochemical, and ultrastructural findings, we conclude that such tumors fall within the spectrum of metaplastic carcinomas of the breast. We believe that this case will further contribute to the understanding of this enigmatic tumor.     

Cytologic diagnosis of metastatic malignant phyllodes tumor of the breast in pleural effusion

A 54‐year‐old woman presented with a left breast mass, discovered 4 years ago but was static until 2 months before presentation, when it showed a rapid increase in size and became painful. Mammography showed a large lobulated mass with internal cystic components (BI‐RADS 4B). A biopsy was performed, followed by modified radical mastectomy. The histologic diagnosis was malignant phyllodes tumor (PT). The patient developed local recurrence 4 months later while on adjuvant radiotherapy and she had a salvage resection. Two months later, she developed massive left pleural effusion. Pleural fluid cytology showed single discohesive markedly atypical cells with hyperchromatic and enlarged nuclei, irregular nuclear membrane, and distinct macronucleoli. Multinucleated forms were also seen. The mononuclear and multinucleated tumor cells cytomorphologically resembled that of the recurrent tumor, indicative of recurrence. Positron emission tomography/computed tomography confirmed recurrence at the left pleura. The patient opted for palliative care and succumbed 1 month later. The current case demonstrated a rare clinical presentation of recurrent malignant PT as massive unilateral malignant pleural effusion. Correlation with previous histologic and cytologic specimens may be useful as similar cytologic features could be identified in subsequent recurrent tumors.     

Primary malignant mixed mesodermal tumor of the gallbladder

Summary A rare case of primary malignant mixed mesodermal tumor of the gallbladder arising in a 75 year old woman is reported. The previously published cases of similar tumors were reviewed in order to outline the histological features and the histogenesis. In diagnosing a malignant mixed mesodermal tumor of the gallbladder it was imperative that we excluded malignant neoplasms with multiple histological patterns. The diffuse and close intermingling of the epithelial and mesenchymal component ruled out a collision tumor. The high mitotic rate, the typical reticulin pattern and the obviously malignant osteoblasts excluded a spindle cell carcinoma with osseous metaplasia. The authors conclude that this is the first case of malignant mixed mesodermal tumor with evident osteosarcomatous areas, described in the gallbladder.     

Comparative study of histological features between core needle biopsy and surgical excision in phyllodes tumor

We analyzed histopathological features of core needle biopsy (CNB) and surgical excision specimen comparatively in 129 patients with surgically proven phyllodes tumor (PT). Stromal characteristics including cellularity, atypia, mitosis, overgrowth, tissue fragmentation, and the tumor margin were assessed. Benign/borderline/malignant phyllodes tumor (PT) were diagnosed in 90 (69.8%)/30 (23.3%)/9 (7.0%) patients. Among the 90 cases of benign PTs, 67 cases (74.4%) were diagnosed concordantly in CNB. For borderline and malignant PTs, three out of eight (26.6%) and four out of nine (44.4%) cases were diagnosed concordantly in CNBs. All 50 cases of discordant diagnosis were underestimated in matched CNBs, especially in their stromal cellularity and mitosis. The size of tumor is larger in discordant cases of PT (P= 0.013). The concordant rate of diagnosis between CNB and surgical excision was about 60% and accordingly, grading of PT based on the histological findings in CNBs has limitation. The discordance comes from heterogeneous stromal properties of PTs.     

Can phyllodes tumours of the breast be distinguished from fibroadenomas using fine needle aspiration cytology?

In an attempt to determine whether it is possible to distinguish phyllodes tumours (PTs) of the breast from fibroadenomas (FAs) using fine needle aspiration cytology (FNAC), we reviewed the cytological slides of eight histopathologically confirmed PTs (six benign and two malignant) and compared them with cytological features of 13 histopathologically confirmed FAs. Each author independently, "blindly" assessed architectural and cytological features of the stromal (six features) and epithelial (seven features) components and the cytological background (three features) and gave a favoured diagnosis for each case. Four of six benign PTs, one of two malignant PTs and 11 of 13 FAs were correctly diagnosed cytopathologically by at least three of the authors. The presence of hypercellular stromal fragments was the most useful feature in distinguishing PTs from FAs, and the presence of cytological atypia of the stromal cells was the most important feature in distinguishing malignant from benign PTs. Sampling error was the most common reason for cytological misdiagnosis of PTs. The two FAs misdiagnosed as PTs were each of cellular type. The results of this study suggest that it is possible to distinguish PTs from FAs using FNAC in most cases. We recommend that if hypercellular stromal fragments are identified in a FNAC specimen of a fibroepithelial lesion, the cytopathologist should raise the possibility of a PT and the surgeon treat the patient accordingly.     

乳腺叶状肿瘤的临床病理学研究

目的 探讨乳腺叶状肿瘤的病理形态学特点,分类和诊断标准,与复发转移的关系及其临床意义。方法 采用回顾性分析的方法对203例有随1访（6－372个月）资料的叶状肿瘤作了详细形态学持征的分析和分类研究,统计学聚类判别分析（SPSS软件10．0版）。结果 良性133例（复发28例）,交界性42例（复发19例,死亡2例）,恶性28例（复发18例,死亡15例）。统计学分析结果显示,肿瘤生长方式,瘤细胞异型性,核分裂象计数和肿瘤性坏死所组成的变量子集分类错判率为零。以此4项为主,完善了病理组织学诊断标准。良性,交界笥和恶性组间复发率,转移和死亡率差异均有显著性意义。肿瘤复发随术式的扩大而减少,2次以上复发占53．85％（35／65）。结论 此瘤可分为良性,低度恶性（交界性）及恶性三种类别。肿瘤生长方式,瘤细胞异型性,核分裂象和肿瘤性坏死是诊断此瘤并对其进行分级（分类）的重要依据。提示首次术式的选择的重要性,良性叶状肿瘤应选择肿物扩大切除术,对于复发的交界性和恶性肿瘤应作乳房切除术。