Stage 4 triple-negative breast cancer: NED after adrenalectomy

What happened, in summary

This 71-year-old woman had a history of triple-negative breast carcinoma, with ER-negative, PR-negative, and HER2-negative disease. She underwent extended radical mastectomy in 2017 followed by adjuvant chemotherapy. During routine follow-up in 2023, her CA15-3 tumor marker became elevated, raising concern for breast cancer recurrence or metastasis. A metastatic workup included chest radiography, bone scan, brain MRI, and contrast-enhanced CT of the chest and abdomen. The imaging found a solid 50 × 36 mm mass in the right adrenal gland, while the other studies did not show metastatic disease. Core needle biopsy of the adrenal lesion suggested pheochromocytoma, and biochemical testing showed elevated serum and urinary normetanephrine and metanephrine, even though she had no symptoms from excess adrenal hormones. She underwent adrenalectomy. The removed adrenal tissue showed two different tumor components. The dominant component had features of pheochromocytoma and stained positive for chromogranin A and synaptophysin. Inside that tissue, pathologists also found a separate nodular focus of pleomorphic cancer cells. Those cells stained positive for cytokeratin, GATA3, and mammaglobin A, confirming metastatic breast carcinoma within the pheochromocytoma. After surgery, CA15-3, metanephrine, and normetanephrine levels normalized. Her case is unusual because the adrenal mass was not simply one tumor: it contained a primary pheochromocytoma and a small metastatic focus from her prior triple-negative breast cancer. The available disease assessment after surgery supported no other detected metastatic sites. The case also shows why biopsy alone did not fully explain the adrenal mass: the sampled tissue suggested pheochromocytoma, while final surgery revealed the hidden metastatic focus.