Comprehensive management of carotid body paragangliomas: A case report on diagnosis, surgical resection, and postoperative surveillance

Abstract

Carotid body paragangliomas (CBPs) are rare, highly vascular neuroendocrine tumors arising at the carotid bifurcation and represent a diagnostic and therapeutic challenge because of their close anatomical relationship with major cervical vessels and cranial nerves. We report the case of a 45-year-old woman who presented with a slowly progressive, painless left lateral cervical mass evolving over a 10-month period. Multimodal imaging evaluation, including high-resolution cervical ultrasound, contrast-enhanced computed tomography, and digital subtraction angiography, demonstrated a well-defined hypervascular lesion at the carotid bifurcation with characteristic splaying of the internal and external carotid arteries, consistent with a Shamblin type II CBP. Biochemical investigations excluded functional tumor activity. The patient underwent complete surgical excision with preservation of the carotid arteries and adjacent cranial nerves. Postoperative imaging follow-up showed no evidence of local recurrence. This case highlights the pivotal role of high-quality multimodal imaging in establishing the diagnosis, guiding preoperative risk stratification and surgical planning, and ensuring effective postoperative surveillance in patients with CBPs.

Introduction

Carotid body paragangliomas (CBPs) are rare, highly vascular neuroendocrine tumors arising from paraganglionic tissue at the carotid bifurcation. Although most lesions are benign, their close anatomical relationship with major cervical vessels and cranial nerves poses significant diagnostic and therapeutic challenges. Clinically, CBPs typically present as a slow-growing, painless lateral neck mass and may occasionally be associated with pulsatility or cranial nerve deficits due to local compression [1].

The diagnosis of CBP relies primarily on advanced imaging modalities. Color Doppler ultrasonography is often the first-line examination, typically demonstrating a well-defined hypoechoic and hypervascular lesion at the carotid bifurcation with characteristic splaying of the internal and external carotid arteries (lyre sign). Contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) provide superior anatomic delineation and demonstrate intense tumoral enhancement related to rich vascularization, while CT or MR angiography allows precise assessment of tumor–vessel relationships. Imaging plays a central role in classifying CBPs according to the Shamblin system, which is essential for surgical planning and risk stratification [2].

Management of CBPs requires a multidisciplinary approach integrating radiological and surgical expertise. Complete surgical excision remains the treatment of choice for most resectable tumors, with outcomes closely related to imaging-based assessment of vascular involvement. This case highlights the pivotal role of high-quality multimodal imaging in diagnosis, preoperative planning, and postoperative surveillance of CBPs [3].

Case presentation

Patient information

A 45-year-old woman with no significant past medical history was evaluated. She had no history of hypertension, diabetes mellitus, autoimmune disorders, prior surgical interventions, tobacco or alcohol use, and reported no occupational exposure to toxins or allergens. Her family history was unremarkable for endocrine or hereditary diseases.

Clinical findings

The patient presented with a persistent left lateral cervical mass evolving over a period of 10 months, which had progressively increased in size during the past 5 months and was associated with episodes of tachycardia. She denied hoarseness, dyspnea, speech fragmentation, or vocal fatigue at the end of the day. Notably, she reported no odynophagia, dysphagia, chronic cough, or pain, highlighting an atypical clinical presentation.

On physical examination, there was a firm, pulsatile left lateral cervical mass exhibiting a palpable thrill and painless on palpation, with partial reduction in size upon compression of the carotid axis. No palpable cervical lymphadenopathy was detected.

Timeline

Timeframe	Event/Action
10 months prior to consultation	Onset: Left lateral cervical mass observed
5 months prior to consultation	Progression: Progressive enlargement of the mass
At the time of diagnosis	Diagnostic investigations: Cervical ultrasonography, CT scan, and carotid angiography performed, confirming a carotid body paraganglioma (Shamblin type II)
Treatment	Surgical intervention: Cervicotomy with excision of the carotid body paraganglioma
Postoperative follow-up	Annual surveillance: Carotid angiography conducted yearly for 2 years, with no recurrence observed

Diagnostic assessment

Multimodal imaging evaluation was performed to characterize the lesion and assess its relationship with adjacent vascular structures.

Routine laboratory tests were unremarkable. To evaluate for a functional CBP, a comprehensive endocrine and biochemical assessment was conducted. Plasma free metanephrines (<57 pg/mL), urinary vanillylmandelic acid (VMA)(<6.7 mg/24 hour), and chromogranin A (<100 ng/mL) were all within normal reference ranges, effectively excluding functional tumor activity. No elevation of inflammatory or infectious markers was observed, indicating the absence of associated systemic processes.

Color Doppler ultrasonography of the neck demonstrated a well-defined, oval-shaped mass at the left carotid bifurcation, causing separation of the internal and external carotid arteries. The lesion exhibited regular margins, homogeneous hypoechogenicity, and marked internal hypervascularity on color Doppler imaging, with identification of a vascular pedicle. The lesion measured approximately 20 mm × 15 mm (Fig. 1).

Fig. 1.

High-resolution color Doppler ultrasound of the left carotid bifurcation demonstrating a well-defined hypoechoic mass with marked internal hypervascularity, consistent with a carotid body paraganglioma.

Contrast-enhanced computed tomography (CT) of the neck revealed a fusiform, well-circumscribed mass centered at the left carotid bifurcation. The lesion was isodense to adjacent muscle on non-contrast images and showed avid enhancement during the arterial phase after contrast administration. Axial, sagittal, and coronal reconstructions enabled precise assessment of tumor morphology, longitudinal orientation, and vascular relationships (Fig. 2, Fig. 3, Fig. 4).

Fig. 2.

Contrast-enhanced axial computed tomography of the neck demonstrating a well-defined, avidly enhancing soft-tissue mass at the left carotid bifurcation, causing separation of the internal and external carotid arteries, consistent with the characteristic lyre sign of a carotid body paraganglioma.

Fig. 3.

Contrast-enhanced sagittal computed tomography of the neck demonstrating a well-defined, intensely enhancing mass centered at the left carotid bifurcation, extending along the carotid space and confirming the vascular nature of the lesion, consistent with a carotid body paraganglioma.

Fig. 4.

Contrast-enhanced coronal computed tomography of the neck demonstrating a well-defined, avidly enhancing mass at the left carotid bifurcation, located between the internal and external carotid arteries and confirming the characteristic vascular pattern of a carotid body paraganglioma.

Digital subtraction angiography confirmed the hypervascular nature of the lesion, demonstrating prominent tumoral blush and characteristic splaying of the internal and external carotid arteries (lyre sign), consistent with a CBP (Fig. 5). CT angiographic reconstructions further delineated the vascular anatomy and tumor–vessel relationships, aiding preoperative planning. Based on imaging findings, the lesion was classified as a Shamblin type II CBP.

Fig. 5.

Digital subtraction angiography of the left carotid bifurcation demonstrating an intensely hypervascular mass with prominent tumoral blush and characteristic splaying of the internal and external carotid arteries, consistent with a carotid body paraganglioma.

Therapeutic intervention

A multidisciplinary tumor board including specialists in otorhinolaryngology, radiology, and vascular surgery reviewed the imaging findings and confirmed the diagnosis of a Shamblin type II CBP, with no evidence of additional cervical or skull base lesions. Based on the imaging-based risk stratification and vascular relationships, complete surgical resection was recommended as the treatment of choice.

The patient underwent cervicotomy with complete excision of the CBP, with preservation of the carotid arteries. The postoperative course was uneventful, and the surgical specimen was removed without vascular or cranial nerve complications. A perioperative image illustrating surgical exposure is provided for completeness (Fig. 6).

Fig. 6.

Intraoperative view during cervicotomy showing surgical exposure of the carotid bifurcation and complete excision of the carotid body paraganglioma with preservation of the carotid arteries.

Follow-up and outcomes

The patient experienced significant clinical improvement, with complete resolution of the left lateral cervical mass and return to normal daily activities. Postoperative follow-up included regular clinical assessments and imaging surveillance with cervical ultrasonography performed annually over a 2-year period. No evidence of local or regional recurrence was detected during follow-up.

Discussion

CBPs, or chemodectomas, are rare neuroendocrine tumors that originate from the paraganglionic tissue located at the carotid bifurcation, where the common carotid artery divides into the internal and external carotid arteries. These tumors are highly vascular and often asymptomatic in their early stages, frequently presenting as a painless neck mass. Despite their benign nature in most cases, CBPs can present significant diagnostic and therapeutic challenges due to their proximity to critical structures such as the carotid arteries, cranial nerves (IX, X, XI, and XII), and the jugular veins. Tumor growth can lead to compression and invasion of these structures, causing symptoms such as dysphagia, hoarseness, and even more severe vascular complications. As a result, timely diagnosis and appropriate management are crucial to preventing long-term sequelae, such as nerve damage and vascular compromise [4].

CBPs are rare tumors, with an incidence of approximately 1-2 cases per 100,000 people annually. They account for about 0.6% of all head and neck tumors and are most commonly diagnosed in individuals aged 40-70 years, with a slight male predominance. The majority of CBPs are sporadic, though familial cases have been reported, often associated with mutations in the SDH (succinate dehydrogenase) gene, which increases susceptibility to paragangliomas. Family history, early age of onset, and multicentric disease are common features in familial cases. These tumors are also more frequent in individuals living at high altitudes, where chronic hypoxia may contribute to their development. Although benign in most cases, about 5%-12% of CBPs demonstrate malignant potential, characterized by local invasion or metastasis to distant organs, including the lungs, liver, and bones [5].

The development of CBPs is thought to arise from paraganglionic cells that originate from the neural crest during embryogenesis. These cells typically form part of the autonomic nervous system, located near major vascular structures, where they function as chemoreceptors monitoring blood oxygen levels. Carotid body tumors arise from these chemoreceptor cells, which become hyperplastic or neoplastic under certain conditions, such as chronic hypoxia or inherited mutations in genes encoding components of the SDH complex. The SDH complex is integral to mitochondrial oxidative phosphorylation, and mutations in this complex are associated with familial paragangliomas, leading to increased tumor formation. In such cases, hypoxia (due to chronic respiratory or cardiovascular conditions) or genetic mutations can trigger abnormal proliferation of these cells, forming the vascularized tumors characteristic of CBPs [6].

The diagnostic evaluation of CBPs begins with clinical suspicion, which is often raised when a patient presents with a painless, progressively enlarging neck mass. Although many CBPs are asymptomatic, they can occasionally cause symptoms such as hoarseness, dysphagia, and vascular disturbances like a pulsatile mass or bradycardia due to carotid sinus compression. In some cases, cranial nerve deficits (eg, hoarseness due to vagus nerve involvement, Horner’s syndrome, or dysphagia) can be present when the tumor compresses the cranial nerves IX, X, XI, or XII. These clinical findings prompt further imaging to confirm the diagnosis and assess the tumor’s size, vascularity, and extent of involvement with adjacent anatomical structures [7].

The primary imaging modalities for diagnosing CBPs are ultrasound (US), CT, and magnetic resonance imaging. US is often used as a first-line imaging tool due to its non-invasive nature. On B-mode US, CBPs are typically hypoechoic, with Doppler imaging revealing hypervascularity consistent with the highly vascular nature of the tumor. While US can detect the presence of a mass and evaluate its vascular characteristics, CT and MRI are superior for detailed anatomical assessment. CT with contrast is particularly effective for identifying the tumor’s size, location, and its relationship with major vessels, such as the carotid arteries. A hallmark sign on CT is Lyre’s sign, in which the tumor causes splaying of the carotid bifurcation. On MRI, CBPs typically appear as hyperintense masses on T2-weighted images, reflecting their vascular content and internal hemorrhage, which may manifest as the salt-and-pepper appearance. MRI provides superior soft tissue contrast and is useful for evaluating cranial nerve involvement, bone invasion, and the degree of vascular encasement [8].

While imaging is critical for diagnosis, histopathological examination is necessary for definitive diagnosis. CBPs are characterized by chief cells, which are neuroendocrine cells that stain positive for synaptophysin, chromogranin A, and S100 protein, and sustentacular cells that provide structural support. Immunohistochemistry plays a pivotal role in confirming the diagnosis, especially when the tumor’s features overlap with other neck masses. Genetic testing for SDH mutations, particularly SDHB, is recommended in cases of familial paragangliomas or in patients with multicentric tumors or those diagnosed at a young age. SDH mutations are associated with a higher risk of malignant transformation and are common in familial cases. Angiography, although largely replaced by CT/MRI angiography, can still be useful in cases where preoperative embolization is planned or when detailed vascular involvement needs to be assessed. PET scans can be utilized for evaluating metastatic potential, particularly in cases of malignant CBPs, helping to identify distant metastases, often to the lungs, liver, or bones [9].

CBPs must be differentiated from other neck masses, such as thyroid tumors, lymphadenopathy, and other paragangliomas. A critical differential diagnosis is thyroid carcinoma, as both can present as well-circumscribed masses in the neck. However, thyroid tumors typically do not exhibit the vascular characteristics of CBPs. Lymphadenopathy may present as a palpable neck mass but usually lacks the pulsatile, vascular features seen in CBPs. Other paragangliomas, such as glomus vagale (vagal paraganglioma) or glomus jugulare (jugular paraganglioma), may also present similarly, though their imaging features, including the displacement of adjacent structures like the carotid arteries and jugular veins, can help distinguish them. Detailed imaging, including CT and MRI, allows for better localization and characterization of the mass, assisting in distinguishing CBPs from these other neoplastic or inflammatory conditions [10].

The treatment of CBPs primarily involves surgical resection, which is the gold standard for most patients, particularly for symptomatic tumors or those with malignant features. Surgical management aims to achieve complete excision of the tumor while minimizing damage to surrounding vascular structures (such as the carotid arteries) and cranial nerves (IX, X, XI, XII). For tumors classified as Shamblin type I (small, non-invasive tumors), resection is typically straightforward with a low risk of complications. In contrast, Shamblin type II and III tumors, which involve more significant vascular and neural structures, require more complex dissection and may necessitate vascular reconstruction. In these cases, the use of preoperative embolization is recommended to reduce blood flow to the tumor, thereby decreasing intraoperative bleeding and improving surgical safety [11].

In patients who are not surgical candidates due to advanced age, comorbidities, or inoperable tumor locations, radiotherapy offers an alternative treatment option. External beam radiation is typically used for residual or recurrent tumors and can provide effective control of tumor growth. In cases of malignant CBPs, particularly when metastasis has occurred to organs such as the lungs or liver, radiation therapy can be employed to manage local invasion and metastatic spread. Stereotactic radiosurgery may also be considered in select cases for smaller, well-defined tumors. While radiation is an effective non-surgical option, it carries risks, including potential damage to surrounding critical structures, such as the cranial nerves or vascular tissues [12].

For asymptomatic or slow-growing CBPs, particularly small tumors or Shamblin type I, a conservative approach with active surveillance may be appropriate. This management strategy is especially suitable for elderly patients or those with limited life expectancy, where the risks of surgery outweigh the benefits. Regular imaging (eg, MRI or CT) is performed to monitor tumor growth, and surgery or radiation therapy is considered if the tumor shows significant increase in size or symptom progression. In cases of malignant tumors, long-term follow-up is essential to monitor for recurrence or metastasis, as even malignant CBPs may have an indolent course with relatively favorable survival rates if treated appropriately [13].

The prognosis for patients with CBPs is generally favorable, especially for benign tumors that are completely resected. The 5-year survival rate for patients undergoing complete resection of benign CBPs is high, with minimal recurrence. However, malignant CBPs, though rare, have a more challenging prognosis, with metastases typically occurring in the lungs, liver, or bones. The 5-year survival rate for metastatic CBPs is lower, and recurrence may occur even up to 20 years after resection. Malignant tumors are associated with higher rates of complications and metastatic disease. Therefore, long-term follow-up is essential, particularly in patients with known malignant or high-risk tumors, to monitor for recurrence or metastasis. Surveillance typically includes regular imaging, such as CT or MRI, and in some cases, PET scans to assess for distant metastasis [14].

Conclusion

In summary, CBPs are rare, highly vascular tumors that arise from paraganglionic cells at the carotid bifurcation. They often present as painless neck masses and can lead to serious complications if left untreated due to their proximity to critical structures like the carotid arteries and cranial nerves. Diagnosis involves imaging techniques like US, CT, and MRI, with histopathology and genetic testing confirming the diagnosis and assessing the risk of malignancy.

The main treatment for CBPs is surgical resection, especially for symptomatic or malignant cases. For larger or inoperable tumors, radiation therapy is an effective alternative, while active surveillance is appropriate for small, asymptomatic tumors. Long-term follow-up is crucial, especially in malignant cases, to monitor for recurrence or metastasis. Early diagnosis and personalized treatment are essential for optimal outcomes.

Patient consent

Written informed consent was duly obtained from the patient for using her data and images for publication of this case report