Phaeochromocytomas are catecholamine-producing tumours derived from the sympathetic or parasympathetic nervous system. The clinical presentation is variable, ranging from adrenal incidentalomas to patients with hypertensive crisis or, rarely, with myocarditis and multiple organ failure. We present the case of a 54-year-old patient admitted to the emergency room due to sudden onset of dyspnoea and tachycardia; after a few minutes, due to the onset of oxygen desaturation and loss of consciousness, he was intubated; a coronary angiography was performed which revealed no significant stenosis; the diagnostic hypothesis therefore led us to think of a genesis of the clinical presentation due to a myocarditis which was then confirmed by cardiac MRI. The aetiology was also clarified by performing abdominal CT and urinary and serum dosage of catecholamines. Phaeochromocytoma confirms itself as an excellent simulator, which is why it is defined as the "great mimic" and is one of the diagnostic hypotheses to think about in young patients with acute multiorgan failure not explained by other causes.

Contributions: VN and MUS helped in conception and design of the study, MUS, VN and PV did data collection, VN and MUS did analysis and interpretation of data; MUS and VN contributed to drafting the work and revising it critically for important intellectual content. All authors approved the final version for publication and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Conflict of interest: The authors declare they have no competing interests, and all authors confirm accuracy.

Grant support & financial disclosures: None

Ethical Consideration, informed consent, and Consent for publication: Informed consent was signed by patient. All mentioned ethical aspects and related consents were taken into consideration during the conduct of this study.