{
  "abstract": "Background: Metaplastic breast carcinoma with mesenchymal differentiation is a rare and morphologically heterogeneous malignancy that may show a biphasic epithelial and sarcomatoid pattern historically termed “carcinosarcoma.” Its synchronous occurrence with invasive papillary carcinoma is exceptionally uncommon and may create diagnostic and therapeutic difficulties. Methods: We report the clinicopathological course of a premenopausal woman with two synchronous breast malignancies. Clinical, radiological, histopathological, and immunohistochemical findings were reviewed, including PD-L1 assessment using the 22C3 antibody, and interpreted in the context of the relevant literature. Results: Definitive surgical pathology demonstrated a 125-mm metaplastic breast carcinoma with mesenchymal differentiation showing carcinosarcoma morphology and a separate 22-mm high-grade triple-negative invasive papillary carcinoma. Sarcomatoid predominance led to the initial interpretation of malignant phyllodes tumor on core biopsy. Axillary lymph-node metastases showed papillary morphology and a concordant immunophenotype, strongly supporting their relationship to the invasive papillary carcinoma. Later supraclavicular recurrence and pulmonary metastases could not be conclusively attributed to either primary tumor. PD-L1 combined positive scores were 25 in both primary tumors and 35 in the supraclavicular metastasis. Pembrolizumab-based therapy was followed by radiological regression and clinical stability. Conclusions: This case highlights the importance of representative sampling, careful characterization of synchronous tumors, comparison of metastatic deposits with all primary lesions, and biomarker reassessment during progression. The observed response should be interpreted in the context of PD-L1-positive metastatic triple-negative breast cancer rather than as evidence of histology-specific pembrolizumab efficacy.",
  "abstract_shown": true,
  "affiliations": [
    "Clinic for General Surgery, University Clinical Center Kragujevac, 34000 Kragujevac, Serbia",
    "Department of Surgery, University Hospital Medical Center Bežanijska Kosa, 11000 Belgrade, Serbia",
    "Department of Surgery, Faculty of Medical Sciences, University of Kragujevac, 34000 Kragujevac, Serbia",
    "Center for Molecular Medicine and Stem Cell Research, Faculty of Medical Sciences, University of Kragujevac, 34000 Kragujevac, Serbia",
    "Center for Medical Oncology, University Clinical Center Kragujevac, 34000 Kragujevac, Serbia",
    "Center for Plastic, Reconstructive and Aesthetic Surgery, University Clinical Center Kragujevac, 34000 Kragujevac, Serbia",
    "Center for Radiation Oncology, University Clinical Center Kragujevac, 34000 Kragujevac, Serbia",
    "Department of Surgery with Anesthesiology, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 10,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Vladimir Tvrdisic"
    },
    {
      "affs": [
        1
      ],
      "name": "Vesna Vulovic"
    },
    {
      "affs": [
        0,
        2,
        3
      ],
      "name": "Bojan Stojanovic",
      "orcid": "0000-0001-6115-612X"
    },
    {
      "affs": [
        4
      ],
      "name": "Marina Petronijevic"
    },
    {
      "affs": [
        5
      ],
      "name": "Milica Dimitrijevic"
    },
    {
      "affs": [
        6
      ],
      "name": "Emilija Subanovic"
    },
    {
      "affs": [
        0
      ],
      "name": "Nina Radosavljevic"
    },
    {
      "affs": [
        0,
        2
      ],
      "name": "Marko Spasic"
    },
    {
      "affs": [
        0,
        2
      ],
      "name": "Bojan Milosevic"
    },
    {
      "affs": [
        1,
        7
      ],
      "name": "Jasna Gacic"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1htmptnvmff6v.bib",
  "cited_by": 0,
  "doi": "10.3390/jcm15197705",
  "fulltext_url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13665783/?tool=EBI",
  "id": "1htmptnvmff6v",
  "issns": [
    "2077-0383"
  ],
  "landing_url": "https://europepmc.org/article/PMC/PMC13665783",
  "language": "eng",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2734|Breast Lesions and Carcinomas"
    ]
  ],
  "openalex": "W7220358465",
  "pdf_url": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13665783/pdf/?tool=EBI",
  "pmcid": "PMC13665783",
  "pmid": null,
  "published": "2026-10-01",
  "publisher": "MDPI AG",
  "ris": "https://research.draconitic.com/paper/1htmptnvmff6v.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:35Z",
      "native_id": "PMC:PMC13665783",
      "source": "europepmc",
      "url": "https://europepmc.org/article/PMC/PMC13665783"
    },
    {
      "first_seen": "2026-10-30T12:20:00Z",
      "native_id": "10.3390/jcm15197705",
      "source": "crossref",
      "url": "https://www.mdpi.com/2077-0383/15/19/7705"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "openalex:2734|Breast Lesions and Carcinomas",
      "subfield": "general"
    }
  ],
  "title": "Synchronous Metaplastic Breast Carcinoma with Mesenchymal Differentiation and Triple-Negative Invasive Papillary Carcinoma: A Case Report and Literature Review",
  "title_text": "Synchronous Metaplastic Breast Carcinoma with Mesenchymal Differentiation and Triple-Negative Invasive Papillary Carcinoma: A Case Report and Literature Review",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:20:00Z",
  "url": "https://research.draconitic.com/paper/1htmptnvmff6v",
  "venue": "Journal of clinical medicine",
  "versions": []
}