Clinical Profile:

A 45 year old woman came with the complaints of a swelling over right side neck associated with difficulty in swallowing since six months . The patient also had history of hoarseness of voice since two months. She gave history of palpitations and sweating on and off. During this period, the patient gave history of increased BP readings. 

Radiological findings:

The sonogram of the neck shows an heterogeneously hypoechoic lesion in the right side of neck between the right ICA and ECA at the bifurcation of right common carotid artery. There is  extensive vascularity within the lesion. 

A four angiogram followed by embolisation was performed. (Fig 4)

Radiological diagnosis:

Carotid body tumor

              Figure 5: Post operative photograph of the tumour mass show the tumour measuring 2.9x3.8cm in its width and length respectively. 

              Figure 6: Histopathology of the tumour shows eosinophilic finely granular cytoplasm giving salt and pepper appearance

Treatment :

The tumor was  removed surgically. Following surgery, the patient made an uneventful recovery and was discharged without any symptoms.

Pathological diagnosis:

Paraganglioma

Timeline :

Discussion

A Carotid body tumour, also known as a chemodectoma or carotid body paraganglioma, is a highly vascular glomus tumour that arises from the paraganglion cells of the carotid body. It is located at the carotid bifurcation with characteristic splaying of the ICA and ECA (1). 

• Typically, carotid body tumours are diagnosed in the 4th to 5th decades and have a female predilection like the other paragangliomas of the head and neck 

• They are the most common type of paraganglioma of the head and neck (account for 60-70%). In approximately 10% of cases, they are bilateral.

• A small number are familial (7-10%), and in such cases, they are frequently multicentric (35-50%) .When familial, they are usually autosomal dominant in inheritance, and associated with 

o Multiple endocrine neoplasia: MEN IIa and MEN IIb

o Phakomatoses

o Tuberous sclerosis complex (TS)

o Neurofibromatosis type 1 (NF1)

o Non Hippel-Lindau disease (vHL)

o Carney triad

Cross-sectional imaging studies can be used to diagnose the lesion and to depict its relationships with the neighbouring vessels.

• CT shows An ovoid avidly enhancing structure at the inferomedial aspect of the carotid bifurcation within the above range should be considered a normal carotid body. When the carotid body measures >6 mm, a small carotid body paraganglioma should be suspected and further evaluated.

• The main characteristics in MR imaging are multiple serpentine and punctuate hypointense foci, related to signal voids in the intratumoral vessels (2).

• The lesions are predominantly T2 hyperintense, more conspicuous when fat saturation is added. T1-weighted sequence findings include a heterogeneous signal inside the lesion, with small areas of hyperintense necrosis and hypointense flow voids. T1 weighted images after the administration of Gadolinium contrast may show the so called “salt and pepper” sign, with the enhancing tumour and slow-flow vessels being the “salt” and the fast-flow small vessels with flow-voids being the “pepper”. The "salt and pepper" sign is also described on T2 images: the "pepper" component represents the small vessels fast-flow voids and the "salt" component represents the tumour matrix, haemorrhage and slow-flow vessels (3).  

•   On DSA, the splaying of the carotid vessels (lyre sign) is identified with an intense blush in tumour with an “early vein” seen due to arteriovenous shunting. The ascending pharyngeal artery is the main contributing supply(4)

Treatment options include (5):

- Embolization: before surgery, reduces the size of the tumour and facilitates the procedure.

- Radiation therapy: is an alternative treatment in cases like bilateral, unresectable and residual tumours, in patients who refuse surgery.

Surgery: The morbidity related to resection of vagal and jugular paragangliomas is significantly higher compared with carotid body tumours, because of the location and surgical approach.

References: 

1. Rao, A (1999) Paragangliomas of the Head and Neck: Radiologic-Pathologic Correlation. Radiographics 19:1605-1632 (PMID: 10555678)

2. Gaillard F, Niknejad M, El-Feky M, et al. Carotid body tumor. Reference article, Radiopaedia.org (Accessed on 25 Dec 2022) https://doi.org/10.53347/rID-4629

3. Carotid Body Tumors: Objective Criteria to Predict the Shamblin Group on MR Imaging.S. Arya, V. Rao, S. Juvekar, A.K. Dcruz 

4.. Paragangliomas of the Head and Neck: Radiologic-Pathologic Correlation Archana B. Rao, Kelly K. Koeller, Carol F. Adair

5. Carotid body tumour : MRI imaging and diagnostic pearls. Servicio Radiodiagnóstico. Complejo Hospitalario Clínico Universitario Santiago de Compostela. Santiago de Compostela, Spain. Unidad de Diagnóstico por Imagen. Complejo Hospitalario Universitario de Vigo. Vigo, Spain.

Acknowledgement :

We are grateful to the Departments of Surgery and Pathology for providing us the images of the operative specimen and histology respectively.