Abstract
Pheochromocytoma (pheo) is adrenal or less frequently extraadrenal tumour of chromafine tissue. Pheos are rare, but cardiovascular and metabolic abnormalities are common.
Unrecognised pheo may lead to fatal hypertensive crisis during anesthesia or other stresses. Proper diagnosis of pheo is thus of utmost importance. 24-h blood pressure (BP) monitoring may contribute to the diagnosis of pheo due to increased BP variability and absence of night BP decline.
Pheo contains large amount of enzyme catechol-O-methyl transpherase (COMT) with subsequent excessive production of COMT metabolites like metanephrines. Measurement of plasma free metanephrines or urinary fraccionated metanephrines has usually higher sensivitivity and specificity compared with plasma or urinary catecholamines.
Morphological diagnosis of adrenal/extraadrenal pheo is based on CT/MR visualisation and 123l-metaiodobenzylguanidin (MIBG) or PET 18F- fluorodeoxyglucose scan. Genetic analysis should be performed in all confirmed pheo cases, especially in younger subjects below 50 years of age in older to detect mutations of following genes: von Hippel-Lindau (VHL), RET-protooncogen, genes encoding B,C and D subunit of mitochondrial sukcinat dehydrogenaze (SDHB, SDHC, SDHD) and neurofibromatosis type I gene.
Pharmacological treatment is based on alpha blockers with subsequent (after 24-48 hours) administration of beta-blockers/especially in patients with tendency to tachycardia/. Following this therapy normalisation of BP is common and laparoscopic excision of pheo tumour can be realised.
Malignant pheos are difficult to treat due to early occurrence of metastasis and lack of response to chemotherapy or in most cases.