Endocrine Abstracts

Introduction: Tumors derived from the extra-adrenal paraganglionic system are rare (incidence: 0.8/100,000 people/year). In this group, 85% are located in the abdomen, 12% in the thorax, and 3% in the head and neck region (HNPC).

Case report: A 46-year-old man, ex-smoker, with a personal history of arterial hypertension, multifactorial secondary polycythemia (obesity, OSA syndrome, hypertrophic cardiomyopathy). Family history: one brother with paraganglioma. The patient presented symptoms of asthenia and neck pain.

Complementary tests: Laboratory: Hb: 20.5 g/dl; Hct: 59.6%; Ca: 12.7 mg/dl; PTH: 353 pg/ml; Calc. urine: 398 mg/24 h; Normetanephrines in urine: 599 mcg/24 h.

Neck CT scan: Bilateral laterocervical masses on both carotid bifurcation. The mass on the right side is 2.4x1.7x3.9 cm and the mass on the left side is 6.5x3.2x7.5 cm.

Scintigraphy (octreotide): laterocervical masses which express somatostatin receptors. The lesion on the right side shows more metabolic activity.

Diagnosis: Bilateral HNPG, clinically silent, which does not extend beyond the cervical region.

Evolution: The patient was operated to treat the HNPG.

Genetic study: Exons 1 to 8 of the SDHB gene, exons 1 to 6 of gene SDHC and exons 1 to 4 of gene SDHD were studied with PCR and BigDye sequencing. No pathogenic mutations or variants of unknown origin were found in the regions analyzed.

Discussion: In this patient is probably a familial paraganglioma syndrome (bilateralism and one brother with a similar condition). The genetic study performed did not come to any final conclusion on the origin of the disease (it did not analyze the SDHAF2 gene, whose mutation is typical in HNPG). The pathogenesis of HNPG is not completely known. The mutation of some specific genes (HID, SDH and VHL) create a similar effect to the stimulation of paraganglionic cells due to chronic hypoxia. Mutations of VHL and SDH are related to these routes of cell hypoxia, and the tumors present associated angiogenesis and a decrease of oxidative metabolism. It is important to mention that HNPG lack histological or molecular markers for malignancy. Up to 50% of all malignant HNPG can be initially classified as benign. Currently, the only clinical predictors for the appearance of metastasis are the presence of the SDHB mutation and a tumor size over 5 cm. Our patient meets the second condition, and therefore will be subject to strict monitoring.