Is sclerosing angiomatoid nodular transformation (SANT) of the splenic red pulp identical to inflammatory pseudotumour? Report of 16 cases

Abstract

To report 16 cases of sclerosing angiomatoid nodular transformation (SANT) of the splenic red pulp. Patients were selected in two phases. An initial group of seven patients was diagnosed with SANT based on the presence of angiomatoid nodules. Sheets of inflammatory fibrosis were found in three patients, resembling inflammatory pseudotumour (IPT); nine further cases of IPT were reviewed. Angiomatoid nodules were detected, leading to the diagnosis of SANT in all cases. The splenic mass (10-150 mm in diameter) was polycyclic, composed of multiple small nodules of loose connective tissue comprising myofibroblasts and a dense network of capillaries as well as some remnants of sinuses. Collagenous fibrosis surrounded them. Bands or large sheets of fibrosis, infiltrated by various inflammatory cells, particularly polytypic plasmacytes, resembling IPT, were present in 10 cases. SANT of the red pulp is a distinct benign pseudotumorous lesion of the spleen characterized by the presence of angiomatoid nodules. We observed such angiomatoid nodules in all our cases of splenic IPT, which were not follicular dendritic cell or myofibroblastic tumours. We therefore recommend careful examination for angiomatoid nodules in all suspected cases of splenic IPT.