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

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.

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.

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.