Catecholamine-induced Myocarditis in a Child with Pheochromocytoma

Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors. The clinical presentation of pediatric PPGLs is highly variable. In cases with pheochromocytoma (PCC), excess catecholamine may stimulate myocytes and cause structural changes, leading to life-threatening complications ranging from stress cardiomyopathy (CM) to dilated CM. Herein, we report the case of catecholamine-induced myocarditis in a child with asymptomatic PCC. A 12-year-and-2-month-old male patient with a known diagnosis of type-1 neurofibromatosis was brought to the emergency department due to palpitations and vomiting. On physical examination, arterial blood pressure was 113/81 mmHg, pulse was 125/min, and body temperature was 36.5 °C. Laboratory tests showed a leucocyte count of 12.8x10³ μL/L and a serum C-reactive protein level of 1.1 mg/dL (Normal range: 0-0.5). Thyroid function tests were normal, while cardiac enzymes were elevated. Electrocardiogram revealed no pathological findings other than sinus tachycardia. The patient was diagnosed with and treated for myocarditis as echocardiography revealed a left ventricular ejection fraction of 48%. Viral and bacterial agents that may cause myocarditis were excluded via serological tests and blood cultures. Blood pressure, normal at the time of admission, was elevated (140/90 mmHg) on the 5^th day of hospitalization. Magnetic resonance imaging revealed a 41x46x45 mm solid adrenal mass. The diagnosis of PCC was confirmed by elevated urinary and plasma metanephrines. The patient underwent surgery. Histopathology of the excised mass was compatible with PCC. It should be kept in mind that, even if there are no signs and symptoms of catecholamine elevation, CM may be the first sign of PCC.