Metastatic Non-small Cell Lung Cancer Masquerading as Metastatic Renal Cell Cancer: A Case Report

Abstract

SESSION TITLE: Cancer Case Report Posters IISESSION TYPE: Case Report PosterPRESENTED ON: Sunday, March 23, 2014 at 01:15 PM - 02:15 PMINTRODUCTION: Clear cell features are most common in carcinomas of lower urinary tract or female reproductive system and rare in lung carcinomas. CASE PRESENTATION: A 61-year-old woman, with 30-pack-year smoking history, presented with progressive severe headaches. Brain MRI revealed an enhancing mass within the right temporal lobe and basal ganglia, associated with vasogenic edema, uncal herniation, and brainstem compression, consistent with multifocal glioma versus metastasis. Coricosteroids were initiated for the cerebral edema. She underwent stereotactic right temporal tumor resection and was discharged home on postoperative day (POD)#1. Pathology revealed metastatic carcinoma with clear cell features (positive for CK7 and CD10; negative for RCC, CK20, and TTF-1) suggesting renal cell carcinoma. After fractionated radiation to the intracranial surgical bed, staging workup revealed right upper lobe lung mass, right paratracheal mediastinal mass, and right thyroid nodule, but no renal lesion. CT-guided right lung mass needle biopsy revealed non-small cell carcinoma (positive for CK7, TTF-1, CK20; negative for CD10) consistent with pulmonary primary, clinical stage-3A. She underwent robotic-assisted video-thoracoscopic right upper lobectomy, right paratracheal mediastinal mass resection, and mediastinal lymph node dissection. Frozen section of the right paratracheal mass revealed metastatic carcinoma with clear cell features, favoring renal cell cancer. Operative (skin-to-skin) time was 171 min; estimated blood loss was 200 mL. Progressive postoperative headaches prompted brain MRI, which was consistent with leptomeningeal carcinomatosis and confirmed on lumbar puncture. Ultrasound-guided right thyroid needle biopsy revealed papillary carcinoma. She required bronchoscopy on POD#5 for mucus plugging and leukocytosis. She was discharged on POD#8. Final pathology revealed 4.5-cm poorly-differentiated carcinoma with clear cell changes and extensive necrosis and 5.5-cm right paratracheal mediastinal metastasis, pT2aN2. She was readmitted on POD#15 for Ommaya reservoir placement for subsequent intrathecal chemotherapy. DISCUSSION: Clear cell features seen on histology are usually diagnostic of renal cell carcinoma, but final diagnosis of primary tumor cell origin is dependent on immunohistochemistry. CONCLUSIONS: We present a case of metastatic non-small cell lung cancer masquerading as metastatic renal cell carcinoma to the mediastinum and brain.Reference #1: None. DISCLOSURE: The following authors have nothing to disclose: Eric Toloza, Anna Cheng, Domenico Coppola, Yuan Shan, Carla Moodie, Joseph Garrett, Diana Krblich, Nam Tran, Soner Altiok, Prudence SmithNo Product/Research Disclosure Information.