32 - A Rare Thoracic Vagal Schwannoma Associated with an Ipsilateral Pulmonary Embolism

Poster Board Number: 32
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Abstract Body : Vagal schwannomas are a rare occurrence, usually presenting in the cervical region, but rarely in the thoracic region, and are usually benign in nature. During dissection of a 95-year-old female donor, a schwannoma, completely encapsulating the vagus nerve, was found in her right thoracic cavity. A cause of death was listed as pulmonary embolism, which was viewed in the right upper lobar pulmonary artery upon dissection of the lungs. The schwannoma was directly superior to, and appeared to be compressing, the arch of the azygos vein as it passed over the right upper lobar pulmonary artery and eparterial bronchus. The tumor was ovoid in shape, and measured approximately 40 mm x 24 mm x 20 mm. It was very rough in texture on its anterior side, but quite smooth on its posterior side.

Schwannomas involving the vagus nerve encompass around 10% of occurrences. Schwannomas of the thoracic region, though rare, are more commonly found in the posterior mediastinum or chest wall, while those involving the superior or middle mediastinum are much less common. Schwannomas can be found on any nerve, but in the posterior mediastinum, they are usually found on the intercostal nerves, and in the superior and middle mediastinum they are most frequently found on the vagus, recurrent laryngeal, and phrenic nerves. This donor’s schwannoma was found in the superior mediastinum, in the region of the great vessels.

Venous compression or pathologies have been associated with cases of pulmonary embolism, such as kidney cysts compressing the inferior vena cava, uterine masses compressing the common iliac veins, or aneurysms of the azygos vein. To our knowledge, a case of venous compression caused by a schwannoma has not been reported, but the size and proximity of the mass to the arch of the azygos vein leads to the reasonable possibility that the tumor may have been linked to the donor’s pulmonary embolism and subsequent death.