# Thymoma with Intravascular Tumor Thrombus in the Left Brachiocephalic Vein: A Case Report

## TL;DR

A 50-year-old woman had a thymoma that extended into a major vein, forming a tumor thrombus, which was successfully surgically removed after careful imaging and planning.

## Contribution

This case report highlights the rare occurrence of intravascular tumor thrombus formation in thymoma and the importance of accurate imaging for diagnosis and surgical planning.

## Key findings

- Contrast-enhanced CT and MRI confirmed thymoma invasion into the left brachiocephalic vein.
- Surgical resection of the tumor and thrombus was achieved without embolization.
- The patient experienced recurrence nine months post-surgery with pleural dissemination.

## Abstract

Thymomas have the potential to locally invade and metastasize, occasionally infiltrating adjacent structures, such as the great vessels and the heart. Although direct extension is the primary mechanism of vascular invasion, rare cases of intravascular growth have also been reported.

We present the case of a 50-year-old woman diagnosed with a thymoma that extended intraluminally into the left brachiocephalic vein (LBCV), forming a tumor thrombus. The patient was referred to our hospital after chest computed tomography (CT), which revealed an anterior mediastinal tumor with a filling defect adjacent to the superior aspect of the tumor. Initially, the defect was thought to be a blood clot because of the preserved vascular wall structure. However, follow-up CT scans conducted 2 weeks later revealed persistence of the defect and a slight increase in size, leading to the diagnosis of a tumor thrombus. Further imaging, including contrast-enhanced CT and magnetic resonance imaging, confirmed thymoma invasion of the LBCV, necessitating surgical intervention. The patient underwent a median sternotomy and tumor resection with combined partial resection of the LBCV and right upper lobe. Intraoperatively, a dilated thymic vein continuous with the tumor was identified. The tumor thrombus was visible through the LBCV wall, aiding in the determination of its extent. The LBCV was clamped proximally and distally, and the dilated thymic vein was ligated and divided. Subsequently, thymectomy encompassing the tumor and partial resection of the LBCV wall were performed to remove the thrombus. Microscopically, the tumor was classified as a type B2 thymoma. No evidence of continuity between the tumor thrombus and the thymic vein was observed. No postoperative complication was observed. Nine months after surgery, the patient experienced recurrence with pleural dissemination and underwent resection.

Thymomas can invade vessels through intravascular growth, and contrast-enhanced CT is important for accurately diagnosing such cases. In this instance, preoperative identification of the tumor thrombus enabled a comprehensive surgical approach, resulting in complete resection of the tumor and thrombus, without the need for embolization. This case underscores the significance of meticulous imaging and surgical planning in the management of complex thymomas to ensure optimal patient outcomes.