Synchronous pure adrenal lipoma and clear cell renal cell carcinoma with sarcomatoid differentiation in a patient with a history of breast cancer: a case report.

The finding of an adrenal mass in a patient with a history of extra-adrenal malignancy represents a diagnostic dilemma, in which metastasis is usually the primary suspicion. Pure adrenal lipomas are extremely rare benign tumors (<5% of adrenal neoplasms) that can coexist with other malignancies. We present the case of a 66-year-old female with a history of infiltrating ductal carcinoma of the breast treated in 2023. During her surveillance protocol, a computed tomography scan revealed a right renal mass and an ipsilateral adrenal lesion with fat density. Given the clinical suspicion of a second primary renal tumor and possible metastatic activity, a right radical nephrectomy was performed. Histopathological analysis confirmed a high-grade clear cell renal cell carcinoma (Grade 4, sarcomatoid features) pT1a, and a synchronous pure adrenal lipoma, definitively ruling out metastasis and myelolipoma. This case underscores the importance of an accurate radiological-pathological correlation to avoid diagnostic bias in complex oncological patients.