Cervical paraganglioma mimicking a thyroid nodule with recurrent nerve involvement

Diagnosis of recurrent laryngeal nerve paralysis associated with an ipsilateral thyroid nodule is highly suggestive of thyroid cancer. We report a case with these initial findings in which a much more uncommon condition was diagnosed: a solitary, sporadic, non-functioning cervical paraganglioma.

The patient was a 38-year-old woman with an unremarkable family history. Her clinical history only included bronchial asthma for which drug treatment was not currently being administered. She had experienced no asthma attacks in recent years.

The patient reported dysphonia for approximately 3 months, and was therefore initially seen at the otolaryngology outpatient clinic. Laryngoscopy revealed left vocal cord paralysis. A computed tomography (CT) scan showed a nodular lesion, approximately 3 cm in size, apparently dependent on the most caudal portion of left thyroid lobe, with posterior and descending extension almost to the sternal manubrium. There were signs of left recurrent nerve paralysis and dilation of the ipsilateral laryngeal ventricle. Thyroid function was normal. Ultrasound examination with fine needle aspiration (FNA) for cytological study of the nodule was requested. Ultrasonography revealed a single 33 mm, hypoechoic thyroid nodule in a very inferior and posterior position at the left thyroid lobe. FNA was performed with difficulty because the nodule was not readily accessible, and the material collected was insufficient for diagnosis.

Because of the suspected signs of the nodule and the difficulty in performing FNA, a repeat FNA was not done, and surgical lesion resection was performed instead. A left hemithyroidectomy was performed, and a nodule adherent to the pharyngolaryngeal muscles that had destroyed the left recurrent nerve was found and resected. Perioperative examination of the surgical specimen revealed suspected medullary thyroid cancer. A total thyroidectomy and excision of the central and left cervical lymph nodes were therefore performed. The final pathological diagnosis, once the tissue was shown to be neuroendocrine in nature but negative for calcitonin at immunohistochemistry, was a 2.7 cm paraganglioma adherent to the lower pole of the left thyroid lobe with no signs of malignancy. Thyroid parenchyma was normal, and the lymph nodes were negative for malignant cells.

Subsequent repeated measurements of fractionated metanephrines and catecholamines in acidified 24-h urine were normal. A metaiodobenzylguanidine (MIBG) total body scan was negative, and a CT scan of the chest and abdomen ruled out other paragangliomas. The patient was therefore diagnosed with a solitary benign cervical paraganglioma, probably non-functioning based on the absence of adrenergic symptoms during tumor manipulation.

Despite the absence of a family history, a genetic study was performed to rule out mutations in succinate dehydrogenase (SDH) genes, initially SDHA and SDHC and, after negative testing, SDHB and a genetic study for von Hippel–Lindau disease. All of these tests were negative.

The patient is currently receiving replacement therapy for postoperative hypothyroidism. Vocal cord paralysis has been well compensated and remains asymptomatic.

Paragangliomas are neuroendocrine tumors arising from the extra-adrenal chromaffin tissue of the autonomic nervous system that may occur in the base of the skull, the neck, the chest, and the abdomen. Cervical tumors account for 0.012% of all human tumors and for 0.6% of head and neck tumors.¹ Most paragangliomas are highly vascularized, benign, and non-functioning. Malignancy is established based on the presence of lymphatic or hematogenous dissemination, rather than on histological findings in the specimen.² Surgical resection is the treatment of choice, and associated chemotherapy or radiotherapy may be performed in malignant cases.² It is estimated that up to 30% of cervical paragangliomas may be familial.¹ Genetic study is therefore recommended, because a positive study involves a risk of developing new tumors and may have implications for the screening of relatives. The genetic changes most closely related to the development of cervical paragangliomas are those occurring in SHD genes, particularly SDHD and SDHC,³ but a significant number of SDHB mutations have also been documented in the Spanish population.¹ They may also be part of von Hippel-Lindau disease and neurofibromatosis type 1. Genetic study of these conditions may therefore be considered if suggested by other clinical data.

To sum up, cervical paragangliomas are uncommon tumors that should be considered in differential diagnosis of neck masses.