(12.13) A NET with Unknown Primary Masked as a Lipid Poor Adrenal Adenoma

Friday, May 10, 2024

12:30 PM – 12:45 PM CDT

Location: ePoster Showcase, Empire Ballroom Foyer, Level 2

Submitter(s)

Gunjan Umarji, MD (she/her/hers)

Fellow
Thomas Jefferson university
Philadelphia, Pennsylvania, United States

Introduction : Neuroendocrine tumors (NETs) of unknown primary account for 12–22% of patients diagnosed with NET and < 5% of cancers of unknown primary. NETs of unknown primary sites, especially well-differentiated NETs, often present initially with liver metastases, and most represent gastroenteropancreatic NETs.

Case(s) Description : A 69-year-old female was found to have an adrenal incidentaloma on a non-contrast CT abdomen, reported as a left 2 x 2 cm indeterminate nodule. The nodule was deemed nonfunctional based on a negative hormonal workup. 1 year later, an MRI abdomen with and without contrast reported a 2.1 x 1.6 cm left adrenal nodule without macroscopic fat or microscopic lipid, without avid enhancement, and without T2 hyper-intensity likely representing a lipid-poor adenoma, with no change. After being lost to follow-up, seven years later, patient presented to ER with left upper quadrant abdominal pain. In the interim, she had a stroke and became wheelchair bound. CT abdomen with contrast showed a poorly circumscribed, heterogeneous, 5.6 x 6.9 x 5.6 cm soft tissue mass on left adrenal with central hyper-density, mild heterogenous enhancement 43 HU pre-contrast to 63 HU post-contrast, abutment of the left renal artery and vein inferiorly and mild thickening of the superior left diaphragmatic crus adjacent to the mass. Multiple sub-centimeter hypoattenuating lesions throughout the liver and new scattered subsolid pulmonary nodules were seen. After ruling out pheochromocytoma, an adrenal biopsy showed a well-differentiated, grade 2 NET with immunohistochemical staining positive for CD 56, synaptophysin and Ki-67 of 20% proliferation rate. Biopsy of liver metastatic nodule showed similar pathology and immunohistochemical staining as left adrenal mass. Oncological decision was made for active surveillance given her significant comorbidities, low grade tumor and asymptomatic state. Three months later, she was hospitalized for lower extremity swelling, found to have a size increase in the adrenal and liver lesions. Repeat liver biopsy showed no transformation to high-grade NET. Patient passed away in hospice care before palliative chemotherapy could be administered.

Discussion :

The median overall survival for unknown primary is the lowest for any regional NET site at 33 months. We present an unfortunate but interesting case of an elderly female presenting with a left “lipid poor” adrenal adenoma, which enlarged over time with hepatic metastases resulting in a final diagnosis of NET of adrenal with unknown primary.