Sclerosing Angiomatoid Nodular Transformation of the Spleen: A Case Report Highlighting Diagnostic Challenges and the Role of Immunohistochemistry.

Sclerosing angiomatoid nodular transformation (SANT) of the spleen is a rare, benign vascular lesion that poses significant diagnostic challenges owing to its nonspecific clinical and radiological features. We herein report the case of a 35-year-old male who presented with chronic left hypochondrial pain and was found to have a splenic mass with poor enhancement on computed tomography (CT) and an increased fluorodeoxyglucose uptake on positron emission tomography-CT. Total splenectomy was performed, and a histopathological examination revealed well-demarcated angiomatoid nodules with varying vascular channels, fibrosclerosis, and hemosiderin deposition. Immunohistochemistry revealed a characteristic tri-phenotypic vascular profile of CD34+/CD31+/CD8- capillaries, CD8+/CD31+/CD34- sinusoid-like vessels, and CD31+ venules. Additional investigations ruled out associations between Epstein-Barr virus (EBV) and IgG4-related diseases. This case underscores the critical role of histopathology and immunohistochemistry in accurately diagnosing SANT and differentiating it from other splenic vascular tumors. We also emphasize the importance of considering SANT in the differential diagnosis of splenic masses, even in younger patients presenting with persistent unexplained abdominal pain.