Endocrine Abstracts

Introduction: Chemodectomas of carotid glomus secret mainly catecholamines and/or ACTH. These tumours are very rare cause of ectopic secretion of parathormone (PTH), althought this possibility should be taken into consideration. Therefore, diagnosis of primary hyperparathyroidism (PHPT) as a cause of hypercalcemia in patients with chemodectoma tumours is problematic and may lead to inappropriate diagnosis and treatment. Presented patient is a 64-years old female with non-operative chemodectomas of carotid glomus diagnosed in 1999 with confirmed SDHD mutation. The patient was treated with external beam radiation, and followed-up because of chronic hypercalcemia coexisting with the tumours. In 2010 the patient was hospitalized because of hypercalcemic crisis with serum calcium (Ca) reaching 3.5 mmol/l and PTH values up to 900 pg/ml. The patient required intravenous bisphosphonates administration, which was ineffective. Magnetic resonance (MRI), ultrasound and tomography did not reveal the occurrence of parathyroid adenoma, therefore the diagnosis of ectopic PTH excretion by chemodectoma was formulated. Difficulties in imaging lesions on the neck by ultrasound and MRI may be partially explained by the fact that the patient underwent subtotal thyroidectomy due to nodular goiter in 1987. In 2015 ultrasound examination showed hypoechogenic focal leasion with increased vascularization measuring 18×28×35 mm in the right thyroid bed. Fine needle aspiration suggested presence of parathyroid cells and concentration of PTH in wash-outs of the needle after Fine Needle Aspiration Biopsy (FNAB-PTH washouts) confirmed this suspicion. Patient was qualified to surgery and operated on in December 2015. Histopathological examination confirmed diagnosis of parathyroid adenoma (diameter of 40 mm) and PTH-positive immunohistochemical staining. Chemodectoma tumours are followed-up and show no progression (MRI imaging) and catecholamine/ACTH activity is stable.

Conclusions: Present case is an example of difficulties of PHPT diagnosis masked by coexisting paragangliomas. Suspicion of paraneoplastic syndrome mislead diagnostic process, and as a result imaging concentrated mainly on the radiological follow-up of the chemodectomas.