A case of a 45-year-old Japanese man with a splenic inflammatory pseudotumor is described. This benign lesion is rarely reported in the world literature. We preoperatively could not rule out the possibility of a malignant neoplasm, due to the fact that the tumor had grown in size after a 2-year observation. However, after performing a splenectomy, a histological examination of the mass revealed an inflammatory process. Inflammatory pseudotumors often pose diagnostic difficulties because the clinical and radiological findings tend to suggest a malignancy. The clinical and pathological features of such previously reported cases are also reviewed.