Response to "CT-guided fine needle aspiration cytology diagnosis of extra-adrenal pheochromocytoma".

Sir,

The authors have done a laudable work in re-addressing the issue of fine needle aspiration cytology (FNAC) role in extra-adrenal paraganglioma (EAP) in their article.[1] I have few comments to put forth in this regard. First, paraganglioma and pheochromocytoma are clinically, biochemically, and pathologically similar, except for unique phenyl-ethanolamine N-methyl transferase (PNMT) expression and epinephrine synthesis in the former.[2] Second, the diagnosis of catecholamine secreting tumors (CST) relies on demonstration of elevated plasma/urinary metanephrines,[3] and not preoperative cytology. FNAC of these tumors are highly non-specific due to significant overlap with other pathologies and degenerative changes such as cystic, hemorrhagic, and necrotic changes.[4]

Third, the statement that “FNAC is not necessarily contraindicated” for the diagnosis of paraganglioma, in my view is fallacious. Evidence suggests that FNAC in a known case of CST is contraindicated and indeed it has to be ruled out before contemplating FNAC.[3] Moreover, FNAC apart from the risk of hemorrhage can lead to hypertensive crises, which can be fatal if not dealt with or anticipated.[5] Fourth, the phenomenon of capsular breach and metastatic spread after FNAC of EAP is possible, in view of high rate of malignancy in EAP.[5] Finally, diagnosis of EAP on FNAC is more incidental and not an intentional event. In view of above facts, FNAC has a limited role of suggesting a neuro-endocrine tumor in an undiagnosed and unsuspected retroperitoneal mass and not recommended in routine practice.