Endocrine Abstracts

Introduction: The classical triad of pheochromocytoma comprises paroxystic headache, palpitation, and diaphoresis. It is a common cause of secondary hypertension. Glycemic abnormalities are not rare. Hyperglycemia and diabetes can be the presenting features of pheochromocytoma. However, cases of hypoglycemia are also described. Malignant tumors account for about 10% of cases.

Case description: In this report, we present a case of a 41-year-old man referred to the endocrinology department for asymptomatic hypoglycemia as an incidental finding on routine laboratory screening. There was no personal or family medical history, and patient was not taking any medication. An insulinoma was initially suspected, and patient underwent abdominal magnetic resonance imaging. The latter revealed right 24 mm hypervascular adrenal mass and normal pancreatic parenchyma. The blood pressure was normal (110/60 mmHg). The laboratory showed an elevated level of chromogranin A (322 mg/l, (N): <100 mg/l) and elevated urinary metanephrines (814 mg/24 h, (N): 74-297) and normetanephrines (755 mg/24 h, (N): 105-354). The fasting insulin, glucose, and c-peptides were in normal range. PET CT showed a strong surexpression of the somatostatin receptors in right adrenal mass. On a non-contrast-enhanced computed tomographic (CT) scan, density of the lesion was 35 HU. On a contrast-enhanced CT, the value was 100 HU. At this stage, a pheochromocytoma was suspected. Surgical resection was performed. The pathology confirmed a pheochromocytoma. It was described as having a high risk of malignancy because of capsular invasion, presence of nuclear atypia, up to eight mitotic figures in 10 high-power fields (hpf), presence of atypical mitoses, and confluent nodules. There was no invasion of peri-adrenal fat, vascular, lymphatic, or peri-neural tissues. The genetic tests showed no mutation in the SDH, RET, VHL, and NF1 genes. The urinary metanephrines and normetanephrines were in the normal range 2 months after the surgery.

Discussion: In conclusion, we present a case of pheochromocytoma in a patient with incidental asymptomatic hypoglycemia. Our case emphasizes that eight percent of patients with pheochromocytoma are completely asymptomatic. Histopathology results demonstrated a tumor with a high risk of malignancy because of the extensive capsular invasion. Nevertheless in literature, the only indicator of malignancy is the presence of distant metastases. Our case also highlights absence of reliable histopathologic methods to distinguish between benign and malignant tumors. However, certain histologic features are more common in malignancy, including extensive capsular invasion (as present in our patient), tumor necrosis, and vascular invasion.