Misdiagnosis of lymphoma as vasculitis: A case report.

NK/T-cell lymphoma (NKTCL) is a highly aggressive malignant tumour with a very poor prognosis, which often poses diagnostic difficulties due to the non-specificity of its clinical presentation. NK/T-cell lymphoma with eosinophilic hyperplasia syndrome is extremely rare. This article describes a patient with NKTCL misdiagnosed as vasculitis who presented with sinusitis, abdominal pain, anorexia, and lung shadows. Additionally, the patient exhibited extremely high eosinophilia levels, which led to a further misdiagnosis of eosinophilic granuloma. We describe the clinical features, diagnostic methods and differential diagnosis of lymphoma and highlights the importance of a multidisciplinary approach in accurate diagnosis and treatment.