Intracardiac leiomyomatosis presenting as an intraoperative consultation

Intravenous leiomyomatosis (IVL) is an extremely rare variant of leiomyoma in which nodular masses of tumor grow within venous channels. Rarely, the tumor can reach the vena cava and right heart. We present a case of a 45-year-old woman, admitted with rapidly evolving exertional dyspnea. Cardiac ultrasonography revealed a "mass in the right chambers". She was submitted to right atriotomy plus tumorectomy, with intraoperative consultation requested. Grossly, the tumor was polypoid, firm, with a smooth surface. The frozen section showed a lesion composed of tortuous vessels and some areas with a fibrillar eosinophil extracellular matrix and others with spindle cells, without significant atypia, mitosis or necrosis. The diagnosis was deferred for definitive paraffin sections. In the definitive H&E and immunohistochemical stains, the case was diagnosed as an IVL and confirmed in the hysterectomy specimen. This is the first case report describing an intraoperative consultation of an intracardiac leiomyomatosis. Clinical information and pathologist awareness to this entity are essential for the correct diagnosis in frozen section.