A 69-year-old man developed bilateral polyarthritis, edematous extremities, and skin desquamation on the fingers and ears. He did not meet the criteria for any connective tissue disease, including rheumatoid arthritis. An examination revealed advanced lung cancer. His systemic manifestations were attributed to paraneoplastic Bazex syndrome and remitting seronegative symmetrical synovitis with pitting edema (RS3PE) syndrome. Treatment with pembrolizumab (an anti-programmed death-1 antibody) for lung cancer relieved his symptoms and shrank the lung tumor. Bazex and RS3PE syndromes are rare paraneoplastic diseases. We herein report this unique case of synchronous development of these two paraneoplastic syndromes in the presence of advanced lung cancer.
A 71-year-old woman with abnormal pulmonary shadows and multiple enlarged thoracic lymph nodes was diagnosed with stage IIB lung adenocarcinoma, pulmonary sarcoidosis, and sarcoidosis-associated lymphadenopathy after biopsies from multiple organ sites. She also had rapidly progressive renal dysfunction, microhematuria, and high myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) concentrations. A renal biopsy revealed granulomatous tubulointerstitial nephritis and necrotizing glomerulonephritis with crescent formation. She was diagnosed with nephritis caused by both sarcoidosis and ANCA-associated vasculitis. Oral prednisolone was administered to treat her nephritis, resulting in improvement in both her renal dysfunction and her sarcoidosis-associated lymphadenopathy.