Pheochromocytoma-Induced Leukocytosis With Concurrent Severe Eosinophilia: A Case Report

Pheochromocytoma is a rare catecholamine-secreting tumor arising from the adrenal medulla. Despite how rare the tumor is, early recognition is critical due to its potential to cause life-threatening complications. Symptoms include episodic hypertension, headaches, and palpitations. Unusual laboratory findings, such as leukocytosis and eosinophilia, are rarely associated with this condition. We report the case of a 42-year-old female presenting with intermittent headaches, episodic hypertension, palpitations, and other symptoms. Initial laboratory investigations showed significant leukocytosis (19.8 x10⁹/L), thrombocytosis (735 x10⁹/L), and eosinophilia (2.7 x10⁹/L), which later reached 5.10 x10⁹/L. Elevated plasma and urinary metanephrines confirmed the diagnosis of pheochromocytoma. CT abdomen showed a large right adrenal mass (10.2 × 9.4 × 9.0 cm) with cystic and hemorrhagic features. Workup to exclude infectious, allergic, and myeloproliferative causes of eosinophilia and leukocytosis was unremarkable. The patient was stabilized medically with alpha- and beta-blockers and scheduled for preoperative embolization followed by laparoscopic adrenalectomy. Pheochromocytoma may present with atypical hematologic abnormalities such as eosinophilia and leukocytosis. This case highlights a rare association between pheochromocytoma and both eosinophilia and leukocytosis. Possible mechanisms include tumor-related secretion of pro-inflammatory cytokines like IL-6 or catecholamine-mediated bone marrow stimulation. Recognition of such atypical presentations can prevent diagnostic delays and facilitate early intervention. This case also highlights an unusual radiological appearance of pheochromocytoma, a large, cystic adrenal mass with internal hemorrhagic changes in a patient with uncontrolled hypertension. Clinicians should consider the diagnosis of phaeochromocytoma in patients with unexplained secondary hypertension and abnormal white cell counts, in the absence of infection or neoplastic disease.