Systemic inflammation associated with splenic metastasis from lung adenocarcinoma successfully treated via splenectomy: A case report

Background The spleen plays a crucial role in immune regulation. Although splenic metastases are rare, abnormal immune responses within the metastatic lesions can occasionally trigger systemic inflammation. Here, we report a case of lung adenocarcinoma with splenic metastasis that induced a cytokine storm-like state and severe anemia, which were drastically resolved by splenectomy. Case Presentation A man in his 70s was diagnosed with stage IVB lung adenocarcinoma (cT1cN3M1b) with high PD-L1 expression (Tumor Proportion Score, 100%). Although pembrolizumab initially led to a partial response, the patient later developed an isolated progression of splenic metastasis. This progression was accompanied by persistent systemic inflammation, characterized by high C-reactive protein (CRP) levels, fever, and secondary anemia, which was refractory to multiple lines of chemotherapy and antibiotics. Laparoscopic splenectomy was performed, which identified the splenic metastasis as the primary source of inflammation. Pathological analysis revealed the histological transformation of pleomorphic carcinoma. Postoperatively, the inflammatory markers and anemia improved rapidly, and the patient’s performance status recovered significantly. Conclusion Although splenic metastasis from lung cancer is typically asymptomatic, this case demonstrated that it can drive drug-resistant systemic inflammation via excessive immune activation. Surgical debulking of the responsible organ has proven to be an effective strategy for controlling tumor-induced systemic inflammation.