RESUMO
Pheochromocytoma is a chromaffin cell-derived adrenal medullary tumour and usually presents with paroxysms of hypertension, palpitations, sweating and headache due to excessive catecholamine release. These tumours can also secrete a variety of bioactive neuropeptides and hormones other than catecholamines, resulting in unusual clinical manifestations. We report a female in her mid-30s who presented with fever, anaemia, thrombocytosis and markedly elevated inflammatory markers. The fever profile, including cultures, was negative. Contrast-enhanced CT of abdomen showed a large solid-cystic right adrenal lesion with elevated plasma-free normetanephrine levels suggestive of pheochromocytoma. The fever persisted despite empirical antibiotics and antipyretics. Interleukin-6 (IL-6) levels were elevated (41.2 pg/mL (3-4 pg/mL)). She was initiated on naproxen (NPX) at a dose of 250 mg two times per day. The patient responded to NPX, and after stabilisation, she underwent an adrenalectomy. There was a complete resolution of fever with normalisation of IL-6 levels postoperatively.