INTERLEUKIN-6-PRODUCING PHEOCHROMOCYTOMA AS A NEW REASON FOR FEVER OF UNKNOWN ORIGIN: A RETROSPECTIVE STUDY.

OBJECTIVE

To explore the fever of unknown origin (FUO) in patients with interleukin-6 (IL-6)-producing pheochromocytoma.

METHODS

Patients with pheochromocytoma were enrolled from June 2014 to April 2017. Clinical characteristics were recorded including sex, age, 24-h urinary catecholamines (norepinephrine, epinephrine, dopamine), tumor size, axillary temperature (AT), white blood cells (WBC), and serum IL-6 and high-sensitivity C-reactive protein (hsCRP) levels. IL-6 secretion by pheochromocytoma was analyzed by immunohistochemistry (IHC).

RESULTS

We identified 29 cases of pheochromocytoma (7 with high AT and 22 with normal AT). Serum IL-6 and hsCRP levels were increased in the high AT group compared with the normal AT group (both P = .001). After pheochromocytoma resection, AT and IL-6 and hsCRP levels decreased significantly ( P<.001, P = .002 and P = .003, respectively). IHC revealed significantly higher IL-6 expression in the high AT group ( P = .002).

CONCLUSION

IL-6-producing pheochromocytoma should be included in the differential diagnosis of FUO.

ABBREVIATIONS

AT = axillary temperature; CT = computed tomography; FUO = fever of unknown origin; IHC = immunohistochemistry; IL-6 = interleukin-6; hsCRP = high-sensitivity C-reactive protein; WBC = white blood cells.