Primary Cardiac Leiomyosarcoma in a Young Patient: A Therapeutic Challenge.

BACKGROUND: Primary cardiac leiomyosarcoma is an extremely rare and aggressive sarcoma. Its diagnosis is challenging, and its treatment is not yet standardized, resulting in a poor prognosis. CASE SUMMARY: A 29-year-old man presented with a 1-month history of respiratory symptoms, initially treated with antiflu medication and antibiotics, showing no clinical improvement. During cardiology consultation, a cardiac mass was identified on echocardiography and subsequently characterized by cardiac magnetic resonance and positron emission tomography. Histopathological and immunohistochemical studies confirmed the diagnosis. The patient remains alive at 20 months while receiving systemic treatment. DISCUSSION: The diagnosis of primary cardiac leiomyosarcoma is challenging due to its rarity and aggressive behavior; it requires multimodal imaging and immunohistochemical confirmation. Its treatment remains nonstandardized, with limited evidence supporting the benefit of combining surgery, chemotherapy, and/or radiotherapy. This case highlights the importance of timely diagnosis and documents longer survival than typically reported.