Unique Case of Primary Malignant Fibrous Histiocytoma of the Right Ventricle with Moderator Band Involvement

Malignant primary tumors of the heart are very rare and in most cases are located in the left side of the heart, but involvement of the moderator band of the right heart has not yet been described in the literature. We report the case of a 22-year-old woman who presented after an episode of transient sudden loss of consciousness. The transthoracic echocardiography (TTE) and transesophageal echocardiography evaluations showed an echogenic mass that originated in the right ventricle and protruded into the tricuspid valve during systole. While operating on the patient, we found a sessile tumor that originated exclusively from the moderator band of the right ventricle. The tumor was completely resected through the tricuspid valve. An immunohistochemistry examination of the tumor confirmed the diagnosis of a malignant fibrous histiocytoma (MFH) (undifferentiated pleomorphic sarcoma). To our knowledge, this case is the first of moderator band involvement among the 50 cases of primary MFH of the heart that have been reported in the literature. After a year and a half, TTE, computed tomography (CT), and positron emission tomography CT (PET-CT) showed the absence of cardiac tumor, a normal tricuspid function, and no metastasis. The completeness of the surgical resection and the absence of local recurrence >1 year after surgery are encouraging signs for the patient's outcome.