Bilateral Adrenal Metastases From Breast Cancer 14 Years After Remission: Diagnostic Value of "Adrenal Thickening".

"Adrenal thickening," a radiologic enlargement of the adrenal gland, with no discrete mass, often benign and nonfunctional, may represent early radiologic sign of malignancy. We present a 64-year-old woman with a history of left lobular breast adenocarcinoma treated with left mastectomy, chemotherapy, radiation, and 4 years of adjuvant hormonal therapy. She remained in remission for 14 years when a new, incidental finding of left adrenal thickening was noted on contrast computed tomography (CT). The patient was asymptomatic, without signs of adrenal hormonal excess. Follow-up imaging revealed bilateral nodular adrenal enlargement with predominant nodules with attenuation >10 Hounsfield units (HU) and high fluorodeoxyglucose (FDG) avidity on positron emission tomography-CT. Biochemical primary adrenal insufficiency was later diagnosed. Biopsy of the adrenal gland confirmed metastatic breast adenocarcinoma. She was initiated on hydrocortisone replacement and combined therapy with ribociclib and letrozole. This case highlights the importance of individualized evaluation of "adrenal thickening," especially in patients with a prior history of malignancy, regardless of the years of remission. Progressive imaging changes and high-risk features such as high FDG avidity and nodules with unenhanced CT attenuation greater than 10 HU should prompt further work-up. Pheochromocytoma must be excluded prior to biopsy due to overlapping imaging characteristics.