A CASE OF CLINICALLY AND BIOCHEMICALLY SILENT GIANT PHEOCHROMOCYTOMA

Abstract

INTRODUCTION/BACKGROUND
With the widespread use of computed imaging and genetic testing, up to 60% of pheochromocytomas are diagnosed in the presymptomatic stage, particularly when the lesion is smaller than 3 cm. We report a rare case of clinically and biochemically silent giant pheochromocytoma.

CASE
A 44-year-old Malay male with a two-year history of hypertension was initially admitted to the surgical team for gallbladder empyema. However, abdominal CT showed a lobulated, heterogeneously enhancing mass with an area of necrosis at the right peritoneal region measuring 11 x 13.5 x 15.2 cm. Subsequent ultrasound-guided biopsy of the mass revealed pheochromocytoma. He was then referred to the Endocrine team for further management. No paroxysmal symptoms were reported by the patient and his blood pressure was well-controlled on a single antihypertensive. Laboratory workup including 24-hour urine catecholamines and 24-hour urine metanephrine were not elevated. Thus, 68Ga/Dotatate scan was performed, which demonstrated evidence of somatostatin receptor avid malignancy in the abdominal mass with no evidence of regional or distant metastasis. Following the scan, serum chromogranin A (CgA) was sent and was found to be elevated (2682.4 ng/ml, normal range: 27-94 ng/ml). After adequate alpha- and beta-blockade, he successfully underwent right adrenalectomy with complete removal of the mass with no complications intra- and postoperatively. The HPE of the mass reported the presence of a wellcircumscribed tumour focally encapsulated by a thin fibrous capsule, with the absence of necrosis and invasion of the vascular, adrenal capsular and periadrenal soft tissue, with a Ki-67 proliferative index of 1%. A repeat abdominal CT done two months post-operatively showed no evidence of local recurrence and a normal CgA level (85.8 ng/ml).

CONCLUSION
Surgery is the primary treatment for pheochromocytoma, and pre-operative alpha- and beta-blockade are essential regardless of tumour size and biochemical status. In patients without elevated levels of catecholamines, CgA is the alternative functional diagnostic and surveillance marker.