Intracystic catecholamine variations in cystic pheochromocytoma.

Purpose: Approximately 20% of pheochromocytomas are cystic in nature. However, research on the correlation between catecholamine and metanephrine fractions in cystic fluid and peripheral blood is limited. This study investigated the relationship between catecholamine fractions and their metabolites in peripheral blood and cystic fluid.

Methods: Five patients with pathologically diagnosed cystic pheochromocytomas were included in the analysis. Catecholamine fractions and their metabolites in the cystic fluid were measured. The relationship between phenylethanolamine N-methyltransferase (PNMT) expression in tumor tissues and catecholamine fractions of cystic fluid was also assessed.

Results: The elevated patterns of catecholamine and metanephrine fractions in the cystic fluid were consistent with those observed in the peripheral blood of two patients. However, in two other patients. discordance was observed, with normetanephrine predominance in the peripheral blood despite adrenaline/metanephrine and noradrenaline/normetanephrine elevations in the cystic fluid. Immunohistochemical analysis revealed that PNMT expression in tumor tissues and the elevated pattern of catecholamine fractions in the peripheral blood were consistent in all patients, except for one patient with non-elevated peripheral blood catecholamines. However, in cystic fluid, the predominantly catecholamine fraction did not consistently align with PNMT expression.

Conclusion: In cystic pheochromocytoma, the elevation patterns of catecholamine fractions in cysts may not align with those in the peripheral blood and may differ relative to PNMT expression in tumor tissues.