BACKGROUND: Primary cardiac tumours are rare, with an incidence ranging from 0.001% to 0.03%. Among these, sarcomas constitute the majority of malignant cases, with malignant fibrous histiocytoma (MFH) being one of the least commonly reported and most aggressive forms. CASE SUMMARY: We present the case of a 40-year-old female who experienced non-specific symptoms, including malaise, dyspnoea, and recurrent chest pain. Initial investigations, including echocardiography, revealed a large mass in the left atrium, initially diagnosed as a myxoma. However, histopathological examination following surgical resection confirmed the diagnosis of MFH. Despite surgical intervention and chemotherapy, the tumour recurred, resulting in the patient's death 2 months after surgery. DISCUSSION: Cardiac sarcomas, particularly MFH, pose significant diagnostic challenges due to their rarity and non-specific symptoms. These malignant tumours often mimic benign conditions, clinically and diagnostically, in modalities such as transoesophageal echocardiography and transthoracic echocardiography. While advanced imaging techniques are critical for accurate diagnosis, socioeconomic factors may limit access. Histopathological examination remains the gold standard for definitive diagnosis. The aggressive nature of these tumours, characterized by rapid recurrence and poor prognosis, highlights the need for improved diagnostic and therapeutic strategies. Future research should focus on targeted therapies and immunotherapy, which promise to improve outcomes in managing these malignancies.