Malignant phyllodes tumor of the breast with osteosarcoma component: a diagnostic dilemma - a case report

Abstract Osteosarcoma component in the breast is rare and can present as a rapidly growing mass with calcification in imaging studies. Differential diagnosis includes metaplastic carcinoma, malignant phyllodes tumor with osteosarcoma component, and exceptionally rare osteosarcoma. Distinguishing the...

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Main Authors: Yuki Muroyama, Minoru Miyashita, Tsuyoshi Miura, Satoko Sato, Mika Watanabe, Takashi Suzuki
Format: Article
Language:English
Published: Springer 2025-07-01
Series:Discover Oncology
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Online Access:https://doi.org/10.1007/s12672-025-03056-3
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author Yuki Muroyama
Minoru Miyashita
Tsuyoshi Miura
Satoko Sato
Mika Watanabe
Takashi Suzuki
author_facet Yuki Muroyama
Minoru Miyashita
Tsuyoshi Miura
Satoko Sato
Mika Watanabe
Takashi Suzuki
author_sort Yuki Muroyama
collection DOAJ
description Abstract Osteosarcoma component in the breast is rare and can present as a rapidly growing mass with calcification in imaging studies. Differential diagnosis includes metaplastic carcinoma, malignant phyllodes tumor with osteosarcoma component, and exceptionally rare osteosarcoma. Distinguishing these tumors is critical for determining therapeutic strategies, especially in differentiating metaplastic carcinoma, as only the former is indicated for adjuvant chemoradiotherapy. Diagnosis can be challenging, however, particularly when the dominant stromal and/or sarcomatous components mask the epithelial component. Here, we present a rare case of breast tumor with osteosarcoma component determined as malignant phyllodes tumor after extensive pathological examination. A 55-year-old woman presented with a left breast mass rapidly growing over the past 3 months. FDG-PET/CT revealed a calcified tumor in the left breast, nearly exposed to the skin, as well as an incidentally found small right breast tumor. Bilateral total mastectomy with sentinel and left axillary lymph node dissection was performed. Microscopic examination of the left breast tumor revealed osteosarcoma components with the atypical cells producing osteoid/neoplastic bone, chondrosarcoma-like components, and massive overgrowth of atypical spindle cells. Extensive pathological examination revealed a small amount of compressed mammary glands without atypia. Collectively, the diagnosis of malignant phyllodes tumor with osteosarcoma component, was made. The patient was discharged without major postsurgical complications and initiated on anastrozole for the concurrently identified hormone-receptor-positive, HER2-negative right breast invasive ductal carcinoma. Breast tumor with osteosarcoma component warrants not only diligent pathological examination to determine the indication for chemoradiotherapy, but also multidisciplinary collaboration to develop effective therapeutic strategies.
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spelling doaj-art-b745fcf9cc3a4e18b1db94ccf60d19e72025-08-20T04:01:34ZengSpringerDiscover Oncology2730-60112025-07-011611610.1007/s12672-025-03056-3Malignant phyllodes tumor of the breast with osteosarcoma component: a diagnostic dilemma - a case reportYuki Muroyama0Minoru Miyashita1Tsuyoshi Miura2Satoko Sato3Mika Watanabe4Takashi Suzuki5Department of Pathology, Tohoku University HospitalDepartment of Breast and Endocrine Surgical Oncology, Graduate School of Medicine, Tohoku UniversityDepartment of Pathology, Tohoku University HospitalDepartment of Pathology, Tohoku University HospitalDepartment of Pathology, Tohoku Kosai HospitalDepartment of Pathology, Tohoku University HospitalAbstract Osteosarcoma component in the breast is rare and can present as a rapidly growing mass with calcification in imaging studies. Differential diagnosis includes metaplastic carcinoma, malignant phyllodes tumor with osteosarcoma component, and exceptionally rare osteosarcoma. Distinguishing these tumors is critical for determining therapeutic strategies, especially in differentiating metaplastic carcinoma, as only the former is indicated for adjuvant chemoradiotherapy. Diagnosis can be challenging, however, particularly when the dominant stromal and/or sarcomatous components mask the epithelial component. Here, we present a rare case of breast tumor with osteosarcoma component determined as malignant phyllodes tumor after extensive pathological examination. A 55-year-old woman presented with a left breast mass rapidly growing over the past 3 months. FDG-PET/CT revealed a calcified tumor in the left breast, nearly exposed to the skin, as well as an incidentally found small right breast tumor. Bilateral total mastectomy with sentinel and left axillary lymph node dissection was performed. Microscopic examination of the left breast tumor revealed osteosarcoma components with the atypical cells producing osteoid/neoplastic bone, chondrosarcoma-like components, and massive overgrowth of atypical spindle cells. Extensive pathological examination revealed a small amount of compressed mammary glands without atypia. Collectively, the diagnosis of malignant phyllodes tumor with osteosarcoma component, was made. The patient was discharged without major postsurgical complications and initiated on anastrozole for the concurrently identified hormone-receptor-positive, HER2-negative right breast invasive ductal carcinoma. Breast tumor with osteosarcoma component warrants not only diligent pathological examination to determine the indication for chemoradiotherapy, but also multidisciplinary collaboration to develop effective therapeutic strategies.https://doi.org/10.1007/s12672-025-03056-3Malignant phyllodes tumorOsteosarcomaBreast
spellingShingle Yuki Muroyama
Minoru Miyashita
Tsuyoshi Miura
Satoko Sato
Mika Watanabe
Takashi Suzuki
Malignant phyllodes tumor of the breast with osteosarcoma component: a diagnostic dilemma - a case report
Discover Oncology
Malignant phyllodes tumor
Osteosarcoma
Breast
title Malignant phyllodes tumor of the breast with osteosarcoma component: a diagnostic dilemma - a case report
title_full Malignant phyllodes tumor of the breast with osteosarcoma component: a diagnostic dilemma - a case report
title_fullStr Malignant phyllodes tumor of the breast with osteosarcoma component: a diagnostic dilemma - a case report
title_full_unstemmed Malignant phyllodes tumor of the breast with osteosarcoma component: a diagnostic dilemma - a case report
title_short Malignant phyllodes tumor of the breast with osteosarcoma component: a diagnostic dilemma - a case report
title_sort malignant phyllodes tumor of the breast with osteosarcoma component a diagnostic dilemma a case report
topic Malignant phyllodes tumor
Osteosarcoma
Breast
url https://doi.org/10.1007/s12672-025-03056-3
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