Computerized tomography without contrast of the abdomen demonstrates a heterogeneous lobulated mass (Fig 1A, arrowhead) with central necrosis that appears to originate in the suprarenal area and extend to the renal hilum (Figs. 1B and 1C) with displacement of the right kidney posteriorly (Fig. 1A, arrow) and inferiorly with focal compression of the inferior vena cava (Fig. 1C, arrow).
Hematoxylin and eosin stained section of a core biopsy of the suprarenal mass shows apparently bland adrenal cortical tissue (Fig 2A). Epithelial membrane antigen (EMA) (Fig. 2B) demonstrates focal positivity. Inhibin alpha is positive in many cells (Fig. 2C). Synaptophysin is negative (Fig. 2D), while vimentin is diffusely positive (Fig. 2E).
The resection specimen consisted of a 12 cm tan-yellow lobulated mass encompassed by abundant adipose tissue. A large area of hemorrhage and necrosis is seen centrally (Fig. 3A). Closer inspection reveals a portion of normal appearing adrenal tissue containing two circumscribed nodules similar in gross appearance to the large mass within the adrenal tissue (Fig. 3B, arrows).
Sections from the resection specimen containing tumor at low power show a neoplasm consisting predominantly of clear cells in a nested and trabecular pattern with interlacing fine vascularity (Fig 4A). Higher power view shows mostly centrally placed nuclei with somewhat clumped chromatin, mild pleomorphism and visible but not overly prominent nucleoli (Fig. 4B). The tumor appears to abut sections of adrenal gland (Fig. 4C) and in some sections corresponding to the nodules seen grossly is totally encompassed by adrenal tissue (Fig. 4D). Variably focal and scattered immunoreactivity is seen with cytokeratin AE1/AE3 (Fig. 4E), CAM5.2 (Fig. 4F), synaptophysin (Fig. 4G), and EMA (Fig. 4H). More numerous positive cells were seen with inhibin alpha (Fig. 4I) and CD10 (Fig. 4J). Vimentin showed strong focal immunoreactivity (Fig. 4K) and accentuated very focal areas with tubule formation (Fig. 4L). Low and higher power views of immunostaining with RCC revealed weak and focal positivity (Figs. 4M and 4N, respectively).
CD10 (Fig. 5A) and RCC (Fig. 5B) show more distinct positivity within the neoplasm (left half) compared to adjacent adrenal tissue while conversely inhibin alpha (Fig. 5C) and synaptophysin (Fig. 5D) demonstrate contrasting positivity within the adrenal portion compared to the neoplasm. Ki67 proliferation marker demonstrated increased nuclear staining in the neoplasm compared to the adrenal tissue (Fig. 5E and 5F). Overall, proliferation index was less than 5 percent.
Electron microscopy showed distortion secondary to formalin fixation. Rough endoplasmic reticulum, occasional lipid droplets and mitochondria (Fig 6A, arrows) were seen. Mitochondria showed lamellar cristae (Fig. 6B)