A rare case of laryngeal paraganglioma presenting as a neck mass

Clinical History

A 40-year-old female patient presented with a swelling on the left side of the neck for 6 months which was slowly increasing in size. Mild dull aching pain was present over the swelling. There was mild difficulty in swallowing. No history of fever, cough or night sweats.

Imaging Findings

CECT scan of the neck shows a bi-lobed intensely enhancing soft tissue lesion, on the left side of the neck at the level of C4, with intra and extra-laryngeal components. The internal component is in the pre-epiglottic fat, abutting the aryepiglottic fold medially. It breaches the thyrohyoid membrane, with an extra-laryngeal component extending anteromedial to sternocleidomastoid and posteroinferior to the left submandibular gland. Laterally, it reaches the deep fascia.
MRI shows that the lesion is isointense on T1WI and hyperintense on T2WI with marked post-contrast enhancement. MR angiogram shows rapid wash-in and early wash-out of contrast.
DSA shows shows early intense tumour blush in the arterial phase with rapid washout in the venous phase. It is seen to be supplied by feeders from branches of the superior thyroid artery.
These findings are suggestive of a laryngeal paraganglioma with extralaryngeal extension.
The lesion was excised and the diagnosis confirmed on histopathological examination.

Discussion

Paragangliomas of the head and neck represent rare tumours of neural crest origin (0.6 % of head and neck tumours). They arise from paraganglion cells scattered throughout the body. The most common type is the carotid body tumour. Others include glomus tympanicum, glomus jugulare and glomus jugulotympanicum.
The larynx contains two groups of paired paraganglia: superior and inferior [1]. Their physiological role is unknown. They serve possibly as extracarotid chemoreceptors or have some effect on respiration via the larynx.
Laryngeal paragangliomas are extremely rare and since being first described in 1955 fewer than 80 such cases have been reported [2]. Laryngeal paraganglioma presenting as a neck mass are rarer still, and only 1 such case has been reported previously from a review of the existing literature [3].
Laryngeal paragangliomas are three times commoner in women than men and have been described in patients from 5-83 years of age (median 44 years) [4]. The vast majority (90%) occur in the supraglottic larynx, presumably arising from the superior pair of laryngeal paraganglia. The rest occur in the subglottis and glottis. Two percent of laryngeal paragangliomas are malignant [5].
They usually present with hoarseness or dysphagia, and a submucosal mass in the region of the aryepiglottic fold/ false vocal cord. Our case is unique due to the fact that the patient presented with a neck swelling, and dysphagia and hoarseness was characteristically absent.
Contrast enhanced CT (CECT) shows soft tissue density tumours with significant post contrast enhancement. This may be inhomogeneous in larger lesions with areas of necrosis and haemorrhage.
MRI shows an iso to hypointense mass on T1 weighted imaging with “Salt and pepper” MR appearance (in lesions >2cm) owing to scattered signal voids (salt=haemorrhage and pepper=flow voids). T2 weighted imaging shows a hyperintense mass with flow voids. Dynamic MRI scanning shows a sharp filling peak and rapid washout with characteristic “dropout” effect. DSA shows intense arterial phase tumour blush with rapid washout in early venous phase [6].
Surgical excision is the treatment of choice for laryngeal paragangliomas [1]. Preoperative angiography and embolisation may be performed to reduce vascularity and aid excision. Selective neck dissection is not usually done due to the benign nature of these lesions. However, recurrence may occur in 17% of cases [4, 5].
Even though laryngeal paragangliomas are extremely rare, they should be considered in the differential of a hyperenhancing soft tissue lesion in the larynx.

Differential Diagnosis List

Final Diagnosis

Laryngeal paraganglioma with extralaryngeal extension.Histopathology report (HPR) - Paraganglioma.

URL:	https://www.eurorad.org/case/13542
DOI:	10.1594/EURORAD/CASE.13542
ISSN:	1563-4086