Ectopic adrenal cortical adenoma arising within the kidney in the setting of adrenal–renal fusion: Two cases mimicking renal cell carcinoma and the role of biopsy and ablation

Figures

• 

  Fig. 1. Contrast-enhanced axial CT of the abdomen during portal venous phase shows a 1.5-cm hypoenhancing cortical mass at the upper pole of the left kidney (arrow), measuring 68 Hounsfield units. The lesion is solid, well circumscribed, and inseparable from the adjacent renal parenchyma, with no macroscopic fat or calcifications.

• 

  Fig. 2. Coronal reformatted contrast-enhanced CT image shows the left upper-pole renal mass (arrow) abutting the superior renal cortex. No discrete fat plane is identified between the lesion and the renal parenchyma. The native adrenal gland (not on same slice) appears separate from the renal mass.

• 

  Fig. 3. Coronal contrast-enhanced CT image demonstrates a lipid-rich left adrenal adenoma (arrow), distinct from the renal mass. The presence of a normal native adrenal gland contributed to preprocedural suspicion for renal cell carcinoma rather than adrenal pathology.

• 

  Fig. 4. Coronal T1-weighted fat-suppressed postcontrast MRI demonstrates a hypoenhancing cortical lesion in the upper pole of the left kidney (arrow). The imaging appearance remains suspicious for renal cell carcinoma, with no radiographic features to suggest ectopic adrenal tissue.

• 

  Fig. 5. Axial T1-weighted in-phase (A) and out-of-phase (B) MRI images demonstrate signal loss within the lesion on opposed-phase imaging (arrow), consistent with microscopic intralesional fat. This finding further supported a diagnosis of clear cell renal cell carcinoma.

• 

  Fig. 6. Intraprocedural axial CT image demonstrates CT-guided percutaneous biopsy and microwave ablation of the left renal mass. A microwave antenna was positioned through the center of the lesion. A coaxial biopsy needle is positioned laterally with a visible open biopsy trough (arrow) through the lesion.

• 

  Fig. 7. Hematoxylin and eosin–stained histologic section (low power, 40×) from CT-guided biopsy demonstrates direct continuity between adrenal cortical tissue (left) and renal cortex (right) without an intervening fibrous capsule. This finding is diagnostic of adrenal–renal fusion.

• 

  Fig. 8. Higher-power (200×) hematoxylin and eosin–stained section demonstrates adrenal cortical tissue composed of uniform polygonal cells with abundant clear cytoplasm and small, centrally located nuclei, consistent with adrenal cortical adenoma. No cytologic atypia or malignant features are identified.

• 

  Fig. 9. Contrast-enhanced axial CT of the abdomen demonstrates a 1.5-cm hypoenhancing exophytic mass arising from the upper pole of the right kidney (arrow). The lesion is solid and well circumscribed, measuring 106 Hounsfield units on portal venous phase.

• 

  Fig. 10. Coronal reformatted contrast-enhanced CT image demonstrates the right upper pole renal mass (arrow) projecting exophytically from the renal cortex. No intervening fat plane or capsule is identified between the lesion and adjacent renal parenchyma.

• 

  Fig. 11. Axial T1-weighted in-phase (A) and opposed-phase (B) MRI images demonstrate signal loss within the lesion on opposed-phase imaging (arrow), consistent with microscopic intralesional fat. This finding further increased suspicion for clear cell renal cell carcinoma.

• 

  Fig. 12. Intermediate-power (40x) histologic section highlights the abrupt transition between adrenal cortical tissue and adjacent renal parenchyma, confirming fusion rather than invasion. The absence of a separating capsule helps distinguish adrenal–renal fusion from clear cell renal cell carcinoma.