Parapharyngeal space neoplasm: pleomorphic adenoma or carcinoid tumour?

We present a case of a parapharyngeal tumour whose preoperative study suggested that it was a neuroendocrine tumour but the final pathologic analysis revealed a pleomorphic adenoma. A female patient aged 36 presented with a mass (5×4,5×2 cm) located in the parapharyngeal space, incidentally identified in a sella turcica MRI, for Cushing syndrome suspicion. Simultaneously, was found a slight elevation of urinary catecholamines. The neck MRI and CT revealed a parapharyngeal mass with heterogeneous characteristics that could correspond a neurogenic tumour. An angiogram showed no appreciable vascularization. A somatostatin receptor scintigraphy revealed a slight increased uptake in the topography of parapharyngeal mass and a body scintigraphy with MIBG I123 showed no alterations. The parapharyngeal mass was approached by a transcervical incision and surgery progressed uneventfully. The histological result was a pleomorphic adenoma. Strangely, the urinary catecholamines became normal after surgery. In suspected parapharyngeal tumours patients should undergo assessment with a neck CT scan or MRI to determine the size and characteristic of the tumour and its relationship to surrounding structures. Tumours found in the prestyloid space rarely need further investigation as almost all arise from the deep lobe of the parotid or minor salivary glands. Poststyloid space tumours need more investigation to exclude paraganglioma. Although the surgical specimen was not subjected to an immunohistochemical analysis, the histological results did not raise doubts that it was a pleomorphic adenoma. The urinary catecholamines’s evaluation is exposed to multiple variables that can influence the result. The preoperative elevated values may not be sufficient to doubt the histological result. Since the salivary glands easily uptake radioactivity in somatostatin receptor scintigraphy, the results also have to be analyzed in a judicious way. However, there is no explanation for the urinary catecholamine values alteration, which resolved with surgery.

Key words: parapharyngeal space; pleomorphic adenoma; neuroendocrine tumours; catecholamines; somatostatin receptor scintigraphy

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Jan 21, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Parapharyngeal space neoplasm: pleomorphic adenoma or carcinoid tumour?
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