A Carotid Body Tumour Mimicking Richter's Transformation of Chronic Lymphocytic Leukaemia

Abstract

Carotid body tumours (CBT), also called carotid paragangliomas, are highly vascular glomus tumours that originate from paraganglionic cells of the carotid body. They are frequently asymptomatic, insidious, and non-secretory in nature. They typically present as a large, non-tender, pulsatile neck mass. Careful evaluation of a neck mass, with the aid of imaging, is necessary to avoid a misdiagnosis. We herein describe a case of a 77-year-old gentleman with a background of chronic B-cell lymphocytic leukaemia, who was found to have a rapidly enlarging, asymptomatic neck mass along with multiple enlarged lymph nodes in the axillae. Given his past medical history, the preliminary diagnosis was Richter's transformation. However, the characteristic splaying of the internal and external carotid arteries on imaging prompted us to consider the diagnosis of a CBT. The patient was referred to vascular surgeons for surgical excision of the tumour. Histology confirmed that the neck mass was indeed a CBT. Ultrasound-guided core biopsy of the axillary lymph nodes revealed a concomitant Hodgkin-like Richter's transformation. This case exemplifies how we were able to differentiate between a CBT and nodal mass with the aid of various imaging modalities. An accurate diagnosis allows clinicians to deliver the appropriate management; the treatment for CBT is surgical excision, whereas chemotherapy is the first-line treatment for Richter's transformation.

Keywords: carotid body tumour; carotid paraganglioma; chemodectoma; fontaine sign; head and neck tumors; lyre sign; non‑functional paraganglioma; richter’s transformation; shamblin; b-cell lymphoma.

Figure 1. Computed tomography (CT) scan of the neck.

Images showing a well-defined and intensely enhancing lesion at the right common carotid artery (CCA) bifurcation, approximately 2.24 cm in craniocaudal dimension, causing splaying of the vessels (Lyre sign). Panel A shows sagittal view. Panel B shows coronal view. Panel C shows axial view.

Figure 2. Computed tomography (CT) scan of the chest, in coronal view, showing an enlarged right axillary lymph node.

Figure 3. Computed tomography (CT) scan of the abdomen, in coronal view, showing multiple hypoechoic lesions within the spleen.

Figure 4. Ultrasound scan (USS) of the right axilla.

Scan demonstrating abnormally hypoechoic lymph nodes with loss of central fatty hilum and central vascularity. The short-axis diameter of the largest lymph node within the right axilla measured 12 mm.

Figure 5. Ultrasound scan (USS) of the neck.

Scan demonstrating an oval-shaped, heterogeneously hypoechoic, and highly vascular lesion at the right common carotid bifurcation. The lesion measured approximately 20 x 25 mm.

Figure 6. Positron-emission tomography (PET) image in coronal view.

Image demonstrating very intense uptake within a soft-tissue abnormality at the right common carotid bifurcation. The maximum standardised uptake value (SUV max) was 29.3.