Right Ventricular Involvement of an Aggressive Malignant Peripheral Nerve Sheath Tumor

We present a case of a 58-year-old woman who had a painful right thigh mass for a few months. A transthoracic echocardiogram revealed no evidence of an intracardiac mass. She had a whole-body positron emission tomography/computed tomography scan two months later that revealed masses in her right lower extremity and a mass in her right ventricle that had not been initially reported. She had been initially diagnosed with an undifferentiated pleomorphic sarcoma, but this diagnosis was changed to a malignant peripheral nerve sheath tumor with repeat pathology. She was subsequently hospitalized. An echocardiogram showed a mass covering 80% of her right ventricle (RV). Serial cardiac magnetic resonance imaging revealed a 9.4 × 5.6 cm RV mass with vascular and avascular portions and inflow and outflow tract obstruction. Computed tomography showed no other metastases. Due to a delay in diagnosis and a decline in left ventricular ejection fraction, the patient could not undergo palliative chemotherapy or radiotherapy.