CASE REPORT
A 70-year-old male presented with mild throat and chest discomfort for four months. A chest x-ray was performed which demonstrated a left upper lobe opacity. On further imaging, contrast-enhanced computed tomography (CECT) chest demonstrated a heterogeneously enhancing oval soft tissue density lesion (3x3x2.9 cm) with a lobulated outline and slight speculation at places involving the apicoposterior segment of the upper lobe of the left lung. Bronchoscopy demonstrated normal findings. He had a history of renal cell carcinoma for which he underwent a right nephrectomy 16 years ago, vertebral fusion surgery 24 years ago, and cholecystectomy 17 years ago. He did not have a history of smoking. The patient was then re-evaluated at our center with a CECT chest and abdomen which showed a 3x3x3.2 cm lesion in the left upper lobe of the lung without enlarged mediastinal lymph nodes. There was no visible recurrence in the right kidney bed. (Figure-1)
CT-guided tru-cut biopsy from the upper lobe of the left lung lesion was diagnosed as clear cell tumor favoring clear cell carcinoma. Later after a month, wedge resection of the left upper lobe of lung was done (Figure-2). Grossly, circumscribed tumor of maximum dimension of 3.5 cm was noted (Figure 3). Histologic sections showed tumor cells arranged in solid sheets and nests. These tumor cells were pleomorphic, polygonal in shape with delineated cell membrane, central nuclei with vesicular chromatin and abundant clear to eosinophilic cytoplasm. Some of the cells showed prominent eosinophilic nucleoli (Figure 4A and 4B). Immunohistochemistry was done to further confirm the diagnosis. On, immunohistochemistry, tumor cells were positive for cytokeratin (CK AE1/AE3), paired box gene (PAX8) , cluster of differentiation 10 (CD10), vimentin, and weakly focal positive PAX2 and negative for CK7, CK20, thyroid transcription factor 1 (TTF1) and P40 (Figure 5). The histomorphological features along with immunohistcohemical analysis favored the diagnosis of metastatic clear cell renal cell carcinoma.
The postoperative period was uneventful. The patient was stable without any new symptoms at seven months of follow-up.