Renal Red Herring

Workup revealed a positive P-ANCA of 1:2560 and myeloperoxidase antibodies (MPO) of >8.0. Proteinase 3 antibodies were negative. While the high P-ANCA titer was suggestive of a possible relapse of Wegener's granulomatosis, imaging of the lesion demonstrated heterogeneous signal on FLAIR with adjacent bony erosion, minimal inflammatory changes, and no sinus disease, which were all atypical of Wegener's granulomatosis. Because there was a compressive optic neuropathy OS and the imaging findings were atypical for orbital involvement from Wegener's granulomatosis, a lateral orbitotomy with biopsy of the orbital mass and lateral decompression of the orbit was performed, for diagnostic and therapeutic purposes. Histologically, the lesion consisted of lobules of clear cells separated by a fine capillary network. The cells had round to oval-shaped nuclei and clear cytoplasm, some with foamy cytoplasmic vacuoles. The nuclei ranged from bland to moderately pleomorphic, with nuclear vacuoles and prominent nucleoli. Immunohistochemical stains were positive for pancytokeratin, AE1/AE3, vimentin, and PAX 8 with weak focal positivity of the RCC marker. Staining was negative for cytokeratin 7. These pathologic findings were consistent with metastatic renal cell carcinoma to the orbit.The patient did not have a prior history of renal cancer. Subsequent CT scan of the chest, abdomen, and pelvis revealed a 11 x 15 x 11 cm right renal mass compatible with renal cell carcinoma. The CT also showed multiple pulmonary nodules and a lytic lesion in the right proximal femur, suspicious for metastases. Cytoreductive nephrectomy was considered, but was not recommended because of the distant metastases and co-morbidities. In addition, he was not a candidate for immunotherapy or for an autologous vaccine trial due to his immunosuppression for underlying Wegener's granulomatosis. He is scheduled to start radiation therapy to the femoral lesion and will undergo pazopanib chemotherapy.