Molecular stability overrides size in giant pediatric pheochromocytoma

Pheochromocytoma is a rare but potentially life-threatening tumor in children, and its diagnosis may be challenging due to variable clinical presentations. We aimed to describe the diagnostic process and clinical outcomes of a child with a giant pheochromocytoma presenting with severe hypertension and metabolic abnormalities.

A 16-year-old female with a three-year history of hypertension and hyperglycemia, previously diagnosed with essential hypertension and type 2 diabetes mellitus, was found to have a 12.4 cm adrenal mass weighing 280 g. Congenital total hemihypertrophy provided an additional clinical clue. Biochemical evaluation demonstrated marked catecholamine excess, impaired glucose regulation (HbA_1c: 6.4 %), low HOMA-IR (2.39), and markedly elevated plasma renin activity (60.8 ng/mL/h), consistent with secondary hyperaldosteronism. Following open total adrenalectomy, biochemical normalization and favorable radiological follow-up were achieved. Despite the large tumor size and multifocal lymphovascular invasion, preserved succinate dehydrogenase subunit B (SDNB) expression and a low Ki-67 proliferation index (2-3 %) were observed.

This case highlights the importance of considering pheochromocytoma in children with persistent hypertension and atypical metabolic findings. Tumor size and individual histological features may not fully reflect biological behavior; integrated assessment incorporating molecular markers may improve risk stratification and clinical management.