Benign phyllodes tumor of the breast recurring as a malignant phyllodes tumor and spindle cell metaplastic carcinoma. Hum Pathol. 2015;46:327-333. [PMID: 25476122 DOI: 10.1016/j.humpath.2014.10.014]

Malignant phyllodes tumor of the breast with predominant osteosarcoma and chondrosarcomatous differentiation: a rare case report and review of literature

Background

Phyllodes tumors (PTs), which account for less than 1% of mammary gland tumors, composed of both epithelial and stromal components. If a malignant heterologous component is encountered, PT is considered malignant. Malignant phyllodes tumors (MPTs) only account for 8% to 20% of PTs. We report a case of MPT with osteosarcoma and chondrosarcoma differentiation and review the literature to discuss the differential diagnosis and therapy.

Case presentation

A 59-year-old Chinese woman come to our hospital because of a palpable mass she had had for 1 months in the left breast. Preoperative core needle biopsy (CNB) was performed on the left breast mass on January 11, 2023. Pathological diagnosis was malignant tumor, the specific type was not clear. Mastectomy and sentinel lymph node biopsy of the left breast was performed. No metastasis was found in 3 sentinel lymph nodes identified by carbon nanoparticles and methylene blue double staining. Heterologous osteosarcoma and chondrosarcomatous differentiation of phyllodes tumor were observed. Immunohistochemistry: spindle tumor cells ER(-), PR(-), HER-2(-), CK-pan(-), CK7(-), CK8(-), SOX10(-), S100(-), and MDM2(-), CK5/6(-), P63(-), P40(-) were all negative. CD34:(+), SATB2(+), P53(90% strong), CD68 (+), Ki-67(LI: about 60%). No ductal carcinoma in situ was found in the breast. Fluorescence in situ hybridization (FISH) indicated USP6 was negatively expressed on formalin-fixed, paraffin-embedded (FFPE) tissue sections.

Conclusion

MPTs are rare, and heterologous differentiation in MPTs is exceedingly rare. It could be diagnosed by pathology when metaplastic carcinoma, primary osteosarcoma, or myositis ossificans were excluded. This case could help clinicians to improve the prognosis and treatment of this disease.

Fibroepithelial tumours of the breast-a review

Fibroepithelial tumours of the breast are biphasic neoplasms composed of both epithelial and stromal elements, including the common fibroadenoma and the infrequent phyllodes tumour. The admixture of epithelium and stroma in the fibroadenoma shows intra- and pericanalicular patterns, and may display a variety of histological changes. Fibroadenoma variants include the cellular, juvenile, myxoid and complex forms. The cellular fibroadenoma may be difficult to distinguish from the benign phyllodes tumour. Stromal mitotic activity can be increased in fibroadenomas in the young and pregnant patients. Phyllodes tumours, neoplasms with the potential for recurrence, show an exaggerated intracanalicular growth pattern with broad stromal fronded architecture and stromal hypercellularity. They are graded into benign, borderline and malignant forms based on histological assessment of stromal features of hypercellularity, atypia, mitotic activity, overgrowth and the nature of the tumour borders. Classification of phyllodes tumours is imperfect, compounded by tumour heterogeneity with overlapping microscopic features among the different grades, especially in the borderline category. Malignant phyllodes tumours can metastasise and cause death. Determining which phyllodes tumours may behave aggressively has been difficult. The discovery of MED12 mutations in the pathogenesis of fibroepithelial tumours, together with other gene abnormalities in the progression pathway, has allowed refinements in diagnosis and prognosis.

Morphologic and genetic heterogeneity in breast fibroepithelial lesions-a comprehensive mapping study

Breast fibroepithelial lesions (FELs) encompass the common fibroadenoma (FA) and relatively rare phyllodes tumour (PT); the latter entity is usually classified as benign, borderline or malignant. Intratumoural heterogeneity is frequently present in these tumours, making accurate histologic evaluation challenging. Despite their rarity, PTs are an important clinical problem due to their propensity for recurrence and, in the case of malignant PT, metastasis. Surgical excision is the mainstay of management. Recent work has uncovered myriad genetic alterations in breast FELs. In this study, exome sequencing was performed on seven cases of morphologically heterogeneous breast FELs, including FAs, PTs of all grades, and a case of metaplastic spindle cell carcinoma arising in PT, in order to elucidate their intratumoural genetic repertoire. Gene mutations identified encompassed cell signalling, tumour suppressor, DNA repair and cell cycle regulating pathways. Mutations common to multiple tumour regions generally showed higher variant allele frequency. Frequent mutations included MED12, TP53, RARA and PIK3CA. Histological observations of increased cellular density and pleomorphism correlated with mutational burden. Phylogenetic analyses revealed disparate pathways of possible tumour progression. In summary, histological heterogeneity correlated with genetic changes in breast FELs.

Giant benign phyllodes breast tumour with pulmonary nodule mimicking malignancy: A case report

BACKGROUND

Phyllodes tumours (PTs) are fibroepithelial breast tumours, which can be classified as benign, borderline or malignant, according to their histological characteristics. While various huge borderline or malignant PTs have been previously described, a benign PT with a pulmonary nodule mimicking malignancy has not yet been reported. In order that doctors may have a comprehensive understanding of super-giant benign PTs (≥ 20 cm), we also performed a literature review to summarize the clinical features, differential diagnosis, and treatment of this disease.

CASE SUMMARY

A 42-year-old woman with severe anaemia presented with a rapidly enlarging right breast mass, measuring approximately 30 cm × 25 cm × 20 cm that was first noticed 1 year previously. A region of skin ulceration and necrosis (20 cm × 15 cm) was observed on the lateral side of the mass. Computed tomography (CT) of the chest revealed a pulmonary nodule, which initially suggested a diagnosis of metastasis. CT showed that the boundaries between the pectoralis major and the mass were blurred, which was presumed to be due to tumour invasion. However, two core needle biopsies of the mass showed no evidence of malignancy. Following these results, the tumour was removed by mastectomy of the right breast. Interestingly, postoperative pathology finally proved the diagnosis of a benign PT. After 1 year of follow-up, wedge resection of the small pulmonary nodule was performed, and it was confirmed that the lung nodule was actually adenocarcinoma rather than metastatic breast cancer. The patient recovered very well without any postoperative treatment.

CONCLUSION

This case is unique in that the giant breast mass initially mimicking a malignant clinical presentation was eventually pathologically confirmed to be a benign PT, which misled the diagnosis and complemented the atypical features of benign PTs. The pathological and immunohistochemical results were important in the differential diagnosis. In addition, total mastectomy should be recommended due to difficulty in the precise diagnosis of PTs, especially in large breast masses. In the literature, almost one-half of super-giant benign cases were thought to be malignant tumours before surgery. This finding is a reminder to consider all conditions in order to make an accurate diagnosis and avoid excessive treatment.

Malignant Phyllodes Tumor Presenting in Bone, Brain, Lungs, and Lymph Nodes

Introduction

Phyllodes tumors (PTs) are rare fibroepithelial tumors of the breast which are classified as benign, borderline, or malignant. Malignant PTs account for <1% of malignant breast tumors, and borderline tumors have potential to progress to malignant tumors. Metastatic recurrences are most commonly documented in bone and lungs. We report an extremely rare presentation of recurrent malignant PTs involving the brain, lung, lymph nodes, and bone.

Case

A 66-year-old female presented with a large breast mass. Biopsy identified malignant PT, treated by mastectomy. One year later she presented with acute back pain; imaging showed pathological L4 spinal compression fracture. Core biopsy confirmed PT. Staging identified additional metastases in the lymph nodes, brain, and lung.

Discussion

PTs are rare and fast-growing tumors that originate from periductal stromal tissues and are composed of both epithelial and stromal components. Histologically, they are classified as benign, borderline, or malignant. The prognosis of the malignant type is poorly defined, with local recurrence occurring in 10–40% and metastases in 10%. Chemotherapy and radiotherapy are generally ineffective in this tumor type. The most common metastatic sites for malignant cases are the lung and bones, but in rare instances, PTs may metastasize elsewhere.

Conclusion

We report a rare presentation of recurrent malignant PT presenting as pathological fracture of the lumbar spine with impingement on the spinal column, along with cerebellar, nodal, and pulmonary metastases. Only 1 similar case has been previously reported.

Molecular alterations in lesions of anogenital mammary-like glands and their mammary counterparts including hidradenoma papilliferum, intraductal papilloma, fibroadenoma and phyllodes tumor

Lesions affecting anogenital mammary-like glands (AGMLG) are histopathologically very similar to those seen in the breast but whether this morphological similarity is also reflected at the genetic level is unknown. To compare the underlying molecular mechanisms in lesions of AGMLG and their mammary counterparts, we analyzed the mutational profile of 16 anogenital neoplasms including 5 hidradenomas papilliferum (HP), 1 lesion with features of HP and fibroadenoma (FA), 7 FA, 3 phyllodes tumors (PhT)) and 18 analogous breast lesions (6 intraductal papillomas (IDP), 9 FA, and 3 PhT) by high-coverage next generation sequencing (NGS) using a panel comprising 50 cancer-related genes. Additionally, all cases were analyzed for the presence of a mutation in the MED12 gene. All detected mutations with allele frequencies over 20% were independently validated by Sanger sequencing (concordance: 100%). Mutations in PIK3CA, AKT1, MET, ABL1 and TP53 genes were found in lesions of AGMLG and also their mammary counterparts. The PI3K-AKT cascade plays a role in tumors arising at both sites. It appears that some histopathologically similar anogenital and breast lesions develop along similar molecular pathways.