Sclerosing angiomatoid nodular transformation of the spleen

Abstract

Sclerosing Angiomatoid Nodular Transformation (SANT) of the spleen is a rare benign lesion of the spleen with unknown etiology. SANT is classically considered to be a female-predominant disease, with most of the patients in the 30- to 60-year age group. Most lesions are found incidentally on imaging. Although SANT has specific imaging findings, the differential diagnosis from other splenic tumors or malignant lesions is very difficult. Histopathologically, these tumors reveal multiple confluent angiomatoid nodules; these nodules are surrounded by concentric collagen fibers exhibiting an inflammatory and myofibroblastic response and are accompanied by numerous erythrocytes and siderophages. The nodules are populated by endothelial cells, phenotypically recapitulating normal splenic vasculature, such as sinusoids, capillaries, and small veins. Nuclear atypia is minimal, mitotic figures are extremely rare, and necrosis is consistently absent. This lesion has a unique immunohistochemical profile characterized by CD34(-)CD31(+)CD8(+) sinusoids, CD34(+)CD31(+)CD8(-) capillaries, and CD34(-)CD31(+)CD8(-) small veins. CD68 is positive in macrophages. Splenectomy is a useful and effective technique for the management of SANT. SANT patients have a good prognosis, with no recurrence after splenectomy. In this review, we discuss the current knowledge of SANT of the spleen and its clinical relevance.