Sclerosing angiomatoid nodular transformation of the spleen presenting as a rapidly growing tumour in a patient with rectal cancer.

A patient with rectal cancer developed a rapidly growing splenic mass 2 years after cancer treatment. Since a metastatic process could not be ruled out, splenectomy was performed, and the tumour emerged as a sclerosing angiomatoid nodular transformation (SANT) of the spleen. SANT is a rare, recently recognised, non-neoplastic vascular lesion of the spleen that radiologically may be difficult to distinguish from vascular splenic lesions such as splenic hamartoma, haemangioma or littoral cell angioma. However, morphologically and immunohistochemically it is separated from those tumours by its unique nodular angiomatoid proliferation pattern. SANT is considered to be a benign lesion. This case is reported because of its important clinical impact for the differential diagnosis of splenic masses. Data regarding growth rates of these lesions are scarce and a growth progression as in this case, that finally led to the indication for splenectomy due to lingering suspicion of malignancy, is novel.