ELEVATED METANEPHRINES IN A NORMOTENSIVE FILIPINO WOMAN WITH A LATERAL NECK MASS

Abstract

INTRODUCTION
Schwannomas are benign biochemically non-secretory neoplasms that originate from the myelin sheaths of nerves. Functioning schwannomas, especially that of the head and neck, are exceedingly rare with only a few published in the literature. This case aims to report the uncommon presentation of a patient with a neck schwannoma in an adult female with elevated urine metanephrines.

CASE
A 33-year-old Filipino female, non-hypertensive, was admitted for a two-year history of progressively enlarging non-tender pulsatile right lateral neck mass, without any symptoms. The patient underwent aspiration biopsy revealing no malignant cells. Contrast-enhanced CT Scan demonstrated well-defined heterogeneously enhancing soft tissue mass in the right paracervical area, with an initial impression of paraganglioma or nerve sheath tumor. To discriminate further, urine metanephrine was ordered and demonstrated high results (3.997 mg, 5.018 mg; Reference: 0-1.00 mg/24hr) on two occasions. Gadolinium-enhanced MRI showed the 6.3x3.9x4 cm mass as isointense on T1WI and hyperintense on T2WI. Despite normotension, terazosin was administered for pre-operative alpha blockade. She underwent excision of the tumor without post-operative complications. On follow-up, the histopathology and immunohistomorphologic features confirmed the mass as a Schwannoma. Four weeks later, the patient remained normotensive and repeat urine metanephrines yielded normal results (0.670 mg, 0.192 mg).

CONCLUSION
Surgery, which remains to be the cornerstone of treatment, heralded the biochemical remission of the urine metanephrines in the patient. Although there were no identified neuroendocrine elements in the histopathology, the decrease in urine metanephrines after tumor removal likely points to a secretory schwannoma.