SAT-496 - Symptomatic Pheochromocytoma with Unusual Tumor Size

Introduction: Pheochromocytomas are rare catecholamine-secreting neuroendocrine tumors that arise from the adrenal medulla. There are several reports of silent pheochromocytoma with small adrenal tumor size; however, the usual adrenal tumor size of a symptomatic pheochromocytoma is more than 4 cm in diameter.

Objective: This is a case report of an adrenal pheochromocytoma with a tumor size of 1.5 cm
Case study: A 73-year-old woman presented to the emergency department twice with a history of headache, sweating, and palpitation. She was found to have BP 200/98 mmHg. During the clinic visit, the BP was 113/72 mmHg without any antihypertensive medications. Serum Metanephrine and Normetanephrine were done twice and reported to be high as follows: Metanephrine 177 ng/l ( < 70), Normetanephrine 305 ng/l (NR < 120), and 3-Methoxytyramine < 12 ng/l ( < 18). CT adrenal showed: right adrenal mass measuring 1.4*1 cm, homogeneous, with an average density of 39 Hounsfield units. It has a poor washout of about 10%. It was classified as indeterminate. The left adrenal was unremarkable. Ga-68 DOTATATE whole body PET/CT scan showed an avid right adrenal lesion, which is highly suggestive of pheochromocytoma.
The patient was started on phenoxybenzamine 10 mg daily. She started to suffer from postural hypotension and tachycardia. Then, she was started on bisoprolol 2.5 mg daily. Then she underwent laparoscopic right adrenalectomy. She was admitted for one day in ICU. Her postoperative course was uneventful. She was discharged on no medications.
Histopathology showed a unifocal intra-adrenal 1.5 cm pheochromocytoma with proliferative activity (Ki-67 Labelling Index). The tumor cells showed diffuse positivity for Synaptophysin, Chromogranin, and S-100.

Discussion: Diagnosis of small pheochromocytoma is challenging, especially since biochemical false-positive results are not uncommon. A nuclear scan with Ga-68 Dotatate PET scan might be helpful in the diagnosis.

Conclusion: A small pheochromocytoma might be symptomatic. The correct diagnosis may require integrating biochemical tests, tumor size, and diagnostic radiological features.

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