Contributed by Marie Dvorakova, M.D. and Guoping Cai, M.D.
This 69-year-old man with a past medical history notable for hypertension, chronic renal insufficiency, spinal stenosis and chronic back pain presented with a 40-pound weight loss due to decreased appetite and with intermittent left chest pain radiating to his left back of approximately one month's duration. A week prior to his admission, he became increasingly confused and weak and fell multiple times at home.
The initial workup included head CT and MRI scans to rule out intracranial bleed. They revealed numerous infra- and supratentorial lesions, largest 4.5 cm, involving both cerebellar and cerebral hemispheres with heterogeneous appearance and overall mild enhancement with more avid enhancement at their margins. In the abdomen, a 12 cm left retroperitoneal soft tissue mass enveloping the left kidney was seen. The left adrenal gland was not visualized. No other lesions were seen on chest and pelvic examination.
The radiographic findings were suspicious for a renal tumor with brain metastasis. A fine needle aspiration of the renal mass was performed, which was followed by a core needle biopsy.
The aspirate smears revealed clusters of malignant epithelial cells in a background of necrosis (Images1, 2 and 3). The tumor cells were intermediate in size, pleomorphic, with scant cytoplasm and hyperchromatic nuclei with fine granular chromatin and inconspicuous nucleoli. Occasional nuclear moldings and crush smearing artifact were present. The cell-block sections of the aspirate showed only scant viable tumor cells with necrotic debris (Image 4). The sections of the core biopsy showed sheets and trabecula of viable tumor cells with similar morphology (Images 5 and 6). Mitoses and apoptosis were frequently seen. Positive immunohistochemical stains included Cam5.2, CK7, CD56, and synaptophysin; the neoplastic cells were negative for vimentin, CK20, AE1/3, LCA, chromogranin, TTF-1 and CDX2. The Ki-67 proliferation index was approximately 90%.