Based on the imaging findings, a preliminary diagnosis of left adrenal pheochromocytoma was made. Possible differentials included paraganglioma, ganglioneuroma and gastrointestinal neuroendocrine tumor. 

The patient went on to have robot-assisted laparoscopic left adrenalectomy.

Preoperative laboratory investigations: plasma metanephrine >5000 ng/l (reference range: <90), and normetanephrine >5000 ng/l (reference range: <129). 

Pathology report:
Size: 20 x 14.0 x 10.0 cm. Weight: 813 grams. Lymphovascular, capsular and adjacent organ invasion: not identified. Margins: free of tumor. Mitosis: > 3/10 HPF. Regional lymph node status: No lymph node submitted. Distant metastasis: not applicable. pTNM stage (by the 8th edition of AJCC): pT2NxMx. 

The adrenal tumor shows classical morphology of pheochromocytoma with extensive central necrosis. The residual viable tumor show atypical worrisome features consistent with malignancy, based on PASS and GAPP pathological grading system. Based on the PASS score, the tumor can accrue up to 17 points: mitosis >3/10 HPF: (2), atypical mitosis: (2), necrosis: (2), diffuse sheats (large nests/diffuse growth): (2), cellular spendling: (2), high cellularity: (2), hyperchromasia: (1), marked nuclear pleomorphism: (1), celluar monotony: (2) and capsular invasion: (1).  According to the GAPP scoring system the tumor corresponds to poorly differentiated type (score=10): Histological pattern: Large and irregular cell nest: (1), pseudo-rosette: (1), high cellularity: (2), Comedo necrosis: (2), Capsular Invasion: (1), Ki-67: (>3%): (2), catecholamine type: norepinephrine: (1).

Diagnosis: pheochromocytoma with malignant features. 

Two weeks after the left adrenalectomy: plasma metanephrine <50 ng/l and normetanephrine 151+ ng/l.