Diagnostic trap: a case report of intimal sarcoma occurring in the left atrium

Our plain-English summary of Diagnostic trap: a case report of intimal sarcoma occurring in the left atrium, by H. Ye, Y. Jing, S. Luo, et al (Frontiers in Cardiovascular Medicine, 2025).

The study

• Authors: H. Ye, Y. Jing, S. Luo, J. Wang
• Journal: Frontiers in Cardiovascular Medicine
• Published: 2025;12:1509505
• Type of article: Case report
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Intimal Sarcoma (IS) is an exceptionally rare and highly aggressive mesenchymal tumor with an uncertain origin. Its clinical and pathological characteristics are challenging to differentiate from other tumors based merely on histological and cytological morphology. Additionally, the immunohistochemical phenotype lacks specificity. Genomically, IS is distinguished by the amplification of the Mouse Double Minute 2 homolog (MDM2) gene. Presently, there are significant obstacles in clinical diagnosis and differential diagnosis of this condition.

Case Demonstration: A 49-year-old male patient was hospitalized due to cough and dyspnea. An echocardiogram indicated a myxoma, leading to the performance of a partial cardiac tumor resection. Post-surgical pathological analysis revealed numerous spindle-shaped tumor cells organized in bundles. The cells displayed significant atypia, areas of necrosis, myxoid degeneration, and pathological mitotic figures. Immunophenotyping indicated positivity for Vimentin, Smooth Muscle Actin, and MDM2, focal positivity for ETS-Related Gene, and a Ki-67 index of 40%, with other markers being negative. Fluorescence in situ Hybridization genetic testing confirmed MDM2 gene amplification. The diagnosis was established as IS of the left atrium, World Health Organization grade 2. Post-surgery, six cycles of chemotherapy were administered. An 11-month follow-up period revealed tumor recurrence and progression, with multiple lesions but no distant metastases.

Conclusions: A rare case of cardiovascular IS located in the left atrium has been documented. Diagnosing this condition poses significant challenges based solely on histological, cytomorphological, and immunophenotypic characteristics, as differentiation from angiosarcoma, malignant mesothelioma, synovial sarcoma, and myxofibrosarcoma is difficult. Consequently, diagnosing IS necessitates a comprehensive approach that integrates clinical presentation, echocardiography, and pathological examinations, encompassing morphology, immunohistochemistry, and genomic analysis. Surgical resection remains the primary treatment option. However, the rate of postoperative recurrence is high, and the prognosis remains poor. Adjuvant chemotherapy and radiotherapy are suggested. In advanced cases, comprehensive immunotherapy methods may be employed to enhance patient survival rates and quality of life.

© 2025 Ye, Jing, Luo and Wang.

In plain English

This case report, by authors from a pathology department in Zunyi, China, described a 49-year-old man who was hospitalized with a 20-day history of cough and shortness of breath. An ultrasound of the heart showed a mass in the left atrium that suggested a myxoma, a benign tumor. During open-heart surgery, surgeons found a solid mass of about 40 mm by 30 mm and smaller nodules on the left atrial wall and the mitral valve. The tumor could not be fully removed. Examination under the microscope, staining tests, and a genetic test showing amplification of the MDM2 gene led to a diagnosis of intimal sarcoma of the left atrium, WHO grade 2. The man received six cycles of chemotherapy. During an 11-month follow-up, the tumor came back and grew, with multiple lesions but no distant spread. He then refused further anti-tumor treatment. The authors concluded that this tumor is difficult to tell apart from other tumors, including malignant mesothelioma, by microscopic appearance and staining alone. The article did not mention asbestos or any other exposure.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: case report (one patient)
• Who was studied: one 49-year-old male patient with cough and shortness of breath; the authors are from the Department of Pathology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou, China; dates of care not given
• Exposure: Not reported; the article does not describe asbestos or any other exposure
• Main results:
  • Before surgery, echocardiography of the patient showed a left atrial mass that suggested myxoma
  • At surgery, a solid mass of about 40 mm by 30 mm was found in the left atrium, and complete removal was not possible
  • The patient's tumor stained positive for Vimentin, SMA and MDM2, with scattered positivity for ERG
  • The genetic test (FISH) on the patient's tumor gave an average MDM2/CEP12 signal ratio of 5.02, above the cutoff of 2, confirming MDM2 amplification
  • The patient's diagnosis was intimal sarcoma of the left atrium, WHO grade 2
  • The patient received six cycles of chemotherapy in the six months after surgery
  • At 11 months of follow-up, the patient's tumor had recurred and progressed, with multiple lesions but no distant metastases
  • The patient refused further anti-tumor treatment because of poor physical condition and cost
• The authors' conclusion: The authors concluded that intimal sarcoma is hard to distinguish from tumors including angiosarcoma, malignant mesothelioma and synovial sarcoma on microscopic appearance and staining alone. In their view, it needs heightened attention from clinicians and pathologists to avoid misdiagnosis.

Topics

Medical terms in this study, explained in our Lexicon: Sarcoma, Mesenchymal Tumor, Differential Diagnosis, Dyspnea, Echocardiogram, Necrosis, Ki-67, Fluorescence In Situ Hybridization (FISH).

Related studies

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• Case report and analysis of the literature on sarcomatous mesothelioma of the left atrium — W. Rouabeh, T. Cherif, et al. (2023)
• New Insights in Pleural Mesothelioma Classification Update: Diagnostic Traps and Prognostic Implications — M.G. Mastromarino, A. Lenzini, et al. (2022)
• The Diagnostic Trap in Radiation-Induced Mesothelioma: Kinetic-Morphological Decoupling Masks Molecular Aggression — N. Fujita, K. Fujita, et al. (2026)
• A diagnostic trap: Malignant pericardial effusion mimicking tuberculous pericarditis — M. Rashmika, U. Jadhav, et al. (2026)
• The diagnostic utility of reduced immunohistochemical expression of SMARCB1 in synovial sarcomas: a validation study — J. Ito, N. Asano, et al. (2016)

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