Parathyroid carcinoma radiographically mimicking a carotid body tumour

Abstract

Parathyroid carcinoma is a rare malignancy and is a cause of primary hyperparathyroidism in less than 1% of cases. The authors present a case in which a lesion, radiologically suggestive of a carotid body tumour, but with the peroperative appearance of a vagal schwannoma had the definitive pathological diagnosis of parathyroid carcinoma. Surgeons should be aware of unexpected malignant lesions involving the parathyroid glands.

Benign neck masses can present diagnostic difficulties when fine needle aspiration combined with appropriate imaging is contraindicated or non-diagnostic. When dealing with rare benign but highly vascular lesions, definitive diagnosis may only be available after formal histological examination, although this can be safely achieved only after definitive surgery. The authors present a case in which a lesion radiologically suggestive of a carotid body tumour, but with the peroperative appearance of a vagal schwannoma, had the definitive pathological diagnosis of parathyroid carcinoma.

Case report

A 71-year-old woman presented with a lump in the right side of her neck. She had a history of hypertension, mitral valve disease and anaemia. Examination demonstrated a 6 cm mass but no other cervical lymphadenopathy, right vocal cord palsy and medial displacement of the right tonsil. A CT scan ( Fig. 1 ) of the mass demonstrated characteristics indicating a carotid body tumour. Haematological investigations were normal. During surgery the common carotid was identified and controlled, and the tumour peeled relatively easily from the entire carotid tree, which was not typical of a carotid body tumour. The mass encased a macroscopically abnormal vagus and hypoglossal nerve that had to be sacrificed in the resection as was the internal jugular vein. Initial postoperative recovery was uneventful but complicated by a late pneumonia requiring admission to the Intensive Therapy Unit. The histopathology demonstrated this to be parathyroid carcinoma. A CT scan of the neck, thorax and abdomen was performed and there were no evidence of disseminated neoplastic disease. Parathyroid hormone levels were found to be within the normal range. Calcium, urea and electrolytes were normal. The postoperative period was complicated with recurrent chest infections. Following multidisciplinary discussion with the patient and her family, the patient declined critical care support for severe respiratory distress and succumbed to pneumonia.

Fig. 1
CT scan of the lesion preoperatively.

Discussion

Parathyroid carcinoma is a very rare malignancy and is a cause of primary hyperparathyroidism in less than 1% of cases . It occurs equally in men and women . Although these tumours are slow growing, they have high propensity to recur locally and recurrent disease is difficult to eradicate . Patients may present with a palpable neck mass . Hoarseness occasionally occurs in these patients, suggesting recurrent laryngeal nerve involvement. Imaging studies commonly used to investigate suspected parathyroid carcinoma are ultrasound, sestimibi scanning, CT and magnetic resonance imaging (MRI) . When parathyroid carcinoma is suspected before operation fine needle aspiration cytology is contraindicated because of the risk of tumour seeding and dissemination . Histologically, a thick capsule, fibrous trabaculae, a trabecular growth pattern and occasionally nuclear pleomorphism are found . Surgery should include resection of the parathyroid en bloc with the adjacent structures, although there is no proof that more extensive surgery is correlated with a more favourable prognosis . Carotid body tumour develops from the paraganglionic cells of the carotid body, which is located at the bifurcation of the common carotid where it can invade or exert pressure on neighbouring vascular and neural tissues . A case of parathyroid carcinoma mimicking the presentation of a carotid body tumour is described. Carcinoma of the parathyroid is a rare endocrine tumour that can be difficult to diagnose. Despite its rarity parathyroid carcinoma should be considered in the differential diagnosis of lesions presenting posterior to the carotid bifurcation. The authors emphasize that surgeons should be aware of unexpected malignant lesions involving the parathyroid glands.

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Feb 8, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Parathyroid carcinoma radiographically mimicking a carotid body tumour
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