The patient is a 44 year old female who was found to have an incidental heterogeneously enhancing splenic mass on CT scan. A follow up CT scan 2 years later demonstrated a solid appearing splenic mass with peripheral enhancement on the arterial phase and progressive enhancement on the portal venous phase. The size had increased from 1.6 cm to 2.9 cm so a splenectomy was performed.

GROSS DESCRIPTION

The spleen grossly weighed 123 grams. Within the lower pole, there was a well circumscribed, red and tan, 3.1 x 2.7 x 2.2 cm mass which abutted the capsule. The remaining splenic parenchyma was unremarkable.

 Other stains:

CD68 - highlighted numerous positive cells
ALK - negative
CD21 - negative
IgG4 - negative
Bartonella - negative
HHV8 - negative
EBV - negative

 The diagnosis of the splenic mass is Sclerosing Angiomatoid Nodular Transformation (SANT).SANT is a recently recognized nonneoplastic vascular lesion of the spleen.The nodules are surrounded by
a variable lymphoplasmacytic infiltrate, spindle cells, and collagenous stroma. The vascular nodules display a complex mixture of endothelial phenotypes resembling splenic sinusoids (CD34-/CD31+/CD8+), capillaries (CD34+/CD31+/CD8-), and small veins (CD34-/CD31+/CD8-).However,the noticeable stromal sclerosis and the presence of plasma cells, which may shares histopathological features associated with IgG4-related sclerosing disease;although the IgG4 is negative in this case.Recently,Diebold et al described that SANT was concomitant within all the splenic Inflammatory Pseudotumour(IPT)they had studied,which were not follicular dendritic cell or myofibroblastic tumours.Thus,they recommended careful examination for angiomatoid nodules in all suspected cases of splenic IPT.

Refferences:

1.Martel M, Cheuk W,et al.Sclerosing angiomatoid nodular transformation (SANT): report of 25 cases of a distinctive benign splenic lesion. Am J Surg Pathol. 2004 ;28:1268-79.

2.Kuo TT,Chen TC,et al.Sclerosing angiomatoid nodular transformation of the spleen(SANT): Clinicopathological study of 10 cases with or without abdominal disseminated calcifying fibrous tumors, and the
presence of a significant number of IgG4+ plasma cells.Pathology International 2009; 59: 844–850

3.Diebold J,Tourneau AL,et al.Is sclerosing angiomatoid nodular transformation (SANT) of the splenic red pulp identical to inflammatory pseudotumour?Report of 16 cases.Histopathology 2008, 53, 299–310.