Sclerosing Angiomatoid Nodular Transformation of the Spleen: A Case Report.

Background Sclerosing angiomatoid nodular transformation (SANT) of the spleen is a non-tumorous benign lesion that originates in the spleen and It is rare. Case presentation A 59-year-old man visited his physician for a checkup. Ultrasonography showed a mass in the spleen, and the patient was referred to our hospital. He tested negative for tumor markers and soluble interleukin-2 receptor (sIL-2R). Abdominal computed tomography revealed a 51-mm hypovascular mass that was slowly enhanced from the portal venous to the equilibrium phases, at the inferior extremity of the spleen. Abdominal magnetic resonance imaging showed a spoke-wheel pattern. Fluorodeoxyglucose positron emission tomography indicated a mild tumor accumulation, with a standardized uptake value max of 5.3. These results led to the suspicion of SANT, angioma, and angiosarcoma. Because the onset of malignant diseases could not be excluded, laparoscopic splenectomy was performed. A brown, round mass, without a capsule but with clear boundaries, was macroscopically observed on the cut surface. In addition, white fibrosis was found in the mass. Histopathological examination revealed nodular angioma lesions, and the proliferation of fibrotic interstices and inflammatory cells was observed between the lesions. Immunohistological examination revealed proliferation in the 3 types of narrow capillaries inside angiomatoid nodules;CD31+/CD34+/CD8-, CD31+/CD34-/CD8+, and CD31+/CD34-/CD8- cells; therefore, the patient was diagnosed with SANT. Conclusions Here, we reported one patient who developed the typical symptoms of SANT. SANT is easily diagnosed by histopathological examination; however, its causes remain unknown. More cases with SANT are required for further analysis.