Lung cancer with a rare kidney inflammation, successfully treated with steroids and radiation

What happened, in summary

A 63-year-old man was admitted after 3 months of repeated high fevers. He also developed small areas of redness on his face and limbs. Chest imaging found several enlarged lymph nodes in the mediastinum, although no clear primary mass was visible in the lungs. Bronchoscopic biopsy of a lymph node showed metastatic adenocarcinoma. The cells were positive for TTF-1 and CK7 and negative for CK20, supporting a lung origin. EGFR mutation testing was negative.

During the same evaluation, his kidney function worsened quickly. Creatinine rose from 0.56 to 3.59 mg/dL within weeks, and urine protein reached 9.21 g/gCr. Kidney biopsy showed severe crescentic inflammation without ANCA antibodies, consistent with ANCA-negative pauci-immune glomerulonephritis.

Prednisolone 40 mg daily was started and then gradually reduced over several months. The fever, swelling, kidney function, and urinary protein all improved. Because the kidney injury made standard chemotherapy difficult, the lung cancer was treated with 60 Gy of radiation directed at the mediastinal disease.

The enlarged cancerous nodes shrank significantly after radiation. He was followed without evidence of renewed kidney inflammation. Five years after discharge, he remained alive without progression of the lung cancer or kidney disease. His course showed long-term control using radiation for the cancer and corticosteroids for the associated kidney problem.

The absence of a visible lung mass made the diagnosis less straightforward, but the lymph-node markers supported a lung primary. Long follow-up showed durable control without chemotherapy.