Clinical History A 59-year-old woman with a medical history notable for abdominal hysterectomy and bilateral salpingo-oophorectomy due to fibroids a decade ago, presented to her primary care physician with a complaint of recurrent exertional syncope. She did not recall symptoms of exertional dyspnea or chest pain, and was unaware of any palpitations or tachycardia. Her physical examination was notable for a soft systolic murmur, and a subsequent cardiac ultrasound revealed a large multi-lobulated mass in the right atrium. The origin of the mass was not visualized, and she was referred for an abdominal and cardiac CT to localize the origin of the tumor.
(Click on images to enlarge)
Figure 1. T2-weighted image showing retroperitoneal mass (arrow) invading the IVC.
Figure 2.Two chamber view of the right heart showing the continuation of the tumor into the right atrium (figure 2A) and prolapsed to the right ventricle during diastole (figure 2B). Figure 3. Gross pathology showing the exact point where the tumor invades the IVC (arrow).
Findings An abdominal MRI (Figure 1) showed a lobulated mass in the retroperitoneal space invading the inferior vena cava (IVC) and extending inferiorly to the main iliac veins and superiorly to the IVC eventually reaching the right ventricle. A CT-guided needle biopsy raised the question of a spindle cell neoplasm. A subsequent cardiac CT showed a lobulated, low-density, heterogeneous mass in the VC extending into the right atrium and prolapsing through the tricuspid valve during systole (Figure 2). The mass did not appear to invade any cardiac structures, raising the question of a leiomyoma. The patient underwent surgical resection of the tumor, and her final pathology confirmed the diagnosis of intravenous leiomyomatosis (Figure 3). Discussion Intravenous leiomyomatosis is a rare proliferation of histologically benign smooth muscle cells within the venous system, whose etiology has been postulated to result from vascular invasion of a uterine leiomyoma. It occurs exclusively in women, and should be considered in the differential upon detection of a right atrial mass in a middle-aged woman with a prior history of hysterectomies due to uterine leiomyoma. Presenting symptoms may include a murmur, palpitations, syncope, pulmonary embolism from superimposed thrombus, or sudden death. Surgical excision is necessary to alleviate symptoms and prevent life-threatening complications.
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