Immune Thrombocytopenia Successfully Controlled by Dissection of an Enlarged Mediastinal Lymph Node Metastasis from Squamous Cell Carcinoma of Unknown Primary: A Case Report

INTRODUCTION: Immune thrombocytopenia (ITP) is an autoimmune hematologic disorder characterized by a reduced platelet count resulting from immune-mediated platelet destruction and/or impaired thrombopoiesis. This condition is often associated with malignant tumors, making perioperative management crucial to maintain hemostasis during and after surgery. Herein, we report a case of ITP successfully controlled following surgical dissection of a large mediastinal lymph node metastasis originating from squamous cell carcinoma of unknown primary. CASE PRESENTATION: A 57-year-old man with poorly controlled ITP was found to have progressively enlarging mediastinal lymph nodes on chest CT over 4 months. The largest lymph node measured 72× 37× 31 mm. The patient received preoperative intravenous immunoglobulin therapy (0.4 g/kg/day) for 4 days, after which mediastinal lymph node dissection was safely performed without hemorrhagic complications. The platelet count improved transiently after surgery. Histopathology revealed metastatic poorly differentiated squamous cell carcinoma, but imaging failed to identify a primary lesion, leading to a diagnosis of squamous cell carcinoma of unknown primary. CONCLUSIONS: With appropriate preoperative management, the platelet count was effectively controlled, allowing safe removal of the large mediastinal lymph node. As the platelet level improved postoperatively, prednisolone tapering was initiated. Given that recurrent malignancy may precipitate a decline in platelet count, close follow-up is warranted.