Incidental finding of a primary cardiac leiomyosarcoma originating from the right atrium of a 25-year old male. A Case Report

BACKGROUND: Primary cardiac tumors are extremely rare and encompass less than 1% of all documented cardiac neoplasms with a majority of these being benign. Among the malignant primary cardiac tumors, leiomyosarcoma accounts for only 1% all documented cases and it commonly involves the left atrium. We present a rare case of a primary cardiac leiomyosarcoma originating from the right atrium of a 25-year-old male.CASE: The patient was a 25-year-old Filipino male who presented with progressive dyspnea, orthopnea, and a large, heterogenous, ovoid mass attached at the atrial septum measuring 7.0 cm x 3.16cm in widest dimension on 2D-echocardiography. The patient eventually underwent emergency excision of the right atrial mass. Post-operatively, the patient did not tolerate the procedure and ultimately expired after attempts of cardiopulmonary resuscitation.HISTOPATHOLOGIC FINDINGS: Microscopic sections show a spindle-cell neoplasm with irregular fascicles and whorled configurations interspersed with inflammatory cells in a fibromyxoid stroma. The spindle cells showed pleomorphic, hyperchromatic nuclei, some with prominent nucleoli and eosinophilic cytoplasm. Mitotic figures, areas of necrosis, and hemorrhages are seen. Immunohistochemical studies show reactivity of the neoplastic cells to Smooth Muscle Actin (SMA) and Vimentin. Masson’s Trichrome Stain is also positive. S100, Myogenin, and Desmin show non-reactivity. Proliferation index is at 15-20% using Ki-67 and p53.CONCLUSION: Primary cardiac leiomyosarcoma is an extremely rare tumor occurring in less than 1% of all documented primary malignant cardiac neoplasms. Metastases originating from other sites are more common. It has an aggressive clinical course and a dismal prognosis with features overlapping that of other soft tissue neoplasms. Hence, additional immunohistochemical studies and special stains should be employed to arrive with a definitive diagnosis so that appropriate management and intervention may be offered to affected patients.