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Pheochromocytoma is an uncommon neuroendocrine tumour arising from the chromaffin cells associated with increased catecholamine production. More than 85% of the tumours are infradiaphragmatic in location, with para-aortic region being the most common site.1
Extra-adrenal pheochromocytoma (EAP) accounts for 10%–15% of pheochromocytoma in adults and 30%–40% in children.2 EAP is sporadic and tends to be larger than the adrenal counterpart at the time of detection.3
Herein, the authors report a rare case of occult bladder EAP that evaded initial imaging modalities due to diagnostic pathway loopholes. A 6-year-old girl had presented with a 1-year history of hypertension, diaphoresis and episodic postmicturition headache. Urinalysis revealed elevated norepinephrine, epinephrine and vanillylmandelic acid levels, highly suspicious for pheochromocytoma. The contrast CT scan of the abdomen and ultrasound (US) for renal artery stenosis performed at another hospital did not include the pelvis in the scanned region and were otherwise unremarkable. Fluorodeoxyglucose-positron emission tomography (PET) showed absent pelvic uptake. The I131-metaiodobenzylguanidine scan was negative. The diagnosis was finally suggested on C11 l-3,4-dihydroxyphenylalanine PET scan of which a focus of increased uptake was noted at the anterior bladder.
A pelvic US demonstrated a 6 cm hypoechoic intramural mass at the dome of the urinary bladder with preserved epithelial lining (figure 1). Colour Doppler imaging (figure 2) revealed prominent peripheral vessels which extended to the rest of the bladder wall. No vascular communication with the adjacent bowel loops was seen. The histopathological diagnosis of EAP was confirmed after an uneventful surgical resection of the bladder tumour.
Although rare, urinary bladder pheochromocytoma should be considered as one of the possible extra-adrenal sites.
The authors recommend the inclusion of pelvic imaging as part of the routine protocol for the screening of pheochromocytoma.
This case illustrates the high-spatial resolution and multiplanar capability of ultrasound evaluation, which mirrored the intraoperative findings in this case.
Contributors VSHC and DLHC contributed to the drafting of the manuscript. SYH contributed to the acquisition of the sonographic images and supervision of the manuscript. WWML supervised the writing of the manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
Patient consent for publication Not required.