Focal mass lesions of the spleen are considered rare. The mass lesions of the spleen usually include malignant and benign tumors, true, false, and parasitic cysts, abscesses, hematomas, and spleen infarctions. Hemangiomas are considered the most common benign neoplasms. Abscesses or spleen infarctions have severe symptoms, pronounced laboratory test changes, disturb the patient and force him to seek help. In contrast, small benign and sometimes malignant neoplasms are asymptomatic for a long time and often are incidental findings. A 38-year-old patient with splenomegaly was admitted to the thoracic surgery center of the Private healthcare institution, Central Clinical Hospital "RZD-Medicine". Abdominal computed tomography showed an enlarged spleen. The blood tests were within the reference values. Given the large size of the spleen, the need to exclude marginal zone lymphoma, clinical presentation, and the risk of spleen rupture, a splenectomy was performed.