Malignant Carotid Paraganglioma: A Case Report

Abstract

Carotid body tumors (CBTs) are rare neoplasms of the neuroectoderm accounting for 0.6% of head and neck tumors, with a 2%-12.5% risk of malignancy. While surgical resection has been associated with a high rate of neurologic and vascular complications, it remains the mainstay of treatment for malignant CBTs. We present the case of a 40-year-old female with a 5-year history of progressively enlarging right-sided neck mass, with MRI and MRA showing a Shamblin grade III CBT encasement of the internal carotid artery (ICA). Blood flow was absent in the petrous segment of ICA, with great collateralization of brain blood supply, enabling en bloc resection of the tumor with a carotid bulb and ligation of the common carotid artery (CCA) without vascular reconstruction. Further, we describe the characteristics and current management for malignant CBTs, including surgical management, pre-surgical embolization, and adjuvant radiation therapy.

Keywords: carotid body tumor; carotid paraganglioma; internal carotid artery ligation; malignant paraganglioma; presurgical embolization.

Figure 1. Pre-operative imaging.

(A-C) MRI angiography transverse views of the petrous segment and terminal branches of ICA, with yellow asterisk depicting the medulla (A), lower midbrain (B), and upper midbrain (C). D) 3D reconstruction of MRI angiography coronal view. E) PET-CT coronal view. ICA, internal carotid artery; PET-CT, positron emission tomography-computed tomography

Figure 2. CT angiography during embolization.

Rich vascular supply of the tumor (top) and the significant reduction in its blood supply after (bottom) embolization of the feeding arteries.

Figure 3. Operative photographs in chronologic order.

Orientation: Left is cephalad, up in anterior, Right is caudal. Tumor marked by yellow asterisk. IJV. internal jugular vein; CCA, common carotid artery; ECA, external carotid artery; CNX, vagus nerve; CNXII, hypoglossal nerve; SCM, sternocleidomastoid muscle

Figure 4. Histopathological assessment of the tumor.

A) Synaptophysin immunohistochemistry. B-E) H&E: B) nuclear atypia (red arrowheads), C) blood vessel invasion depicted by presence of tumor (*) in the vascular space containing blood (black arrowhead), D) lymphatic invasion depicted by presence of tumor in vascular space without blood,  E) perineural invasion depicted by presence of tumor (*) adjacent to nerve (above red dashed line).