Sclerosing angiomatoid nodular transformation mimicking a splenic metastasis from rectal cancer: A case report.

Sclerosing angiomatoid nodular transformation (SANT) is a rare, benign lesion of the spleen. Preoperative diagnosis of SANT without pathological examination poses significant challenges, particularly in patients with a previous history of malignancy. The present study describes the case of a 53-year-old woman that presented to our institution with general fatigue and anemia. Based on a diagnosis of rectal cancer, the patient underwent curative surgery. Postoperatively, with minor leakage and the need for endoluminal drainage, the patient was monitored without adjuvant chemotherapy. A total of 1 year post-operation, enhanced computed tomography (CT) revealed a low-density lesion measuring 7 mm in the spleen. While metachronous metastasis was considered, there was no accumulation of 18F-fluorodeoxyglucose, and the levels of tumor markers, such as carcinoembryonic antigen and carbohydrate antigen 19-9, remained unremarkable. Regular surveillance through contrast-enhanced CT was performed. Over a period of 3 years, the tumor gradually increased to 25 mm. After a diagnosis of metachronous metastasis from rectal cancer, the patient opted for surgery, and laparoscopic splenectomy was performed successfully. Histopathological examination of multiple angiomatoid nodules in the fibrosclerotic stroma confirmed the diagnosis of SANT. The postoperative course of the patient was uneventful. In cases of SANT following a prior malignancy, splenectomy should be considered for both diagnostic and therapeutic purposes.