Vascular tumors
Sclerosing angiomatoid nodular transformation

Reviewer: Vijay Shankar, M.D. (see Reviewers page)

Revised: 11 September 2015, last major update January 2014

Copyright: (c) 2003-2015, PathologyOutlines.com, Inc.

PubMed Search: sclerosing angiomatoid nodular transformation of the spleen

Cite this page: Sclerosing angiomatoid nodular transformation. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/spleensclerosingangiomatoid.html. Accessed February 21st, 2018.
Definition / general
  • Sclerosing Angiomatoid Nodular Transformation (SANT): rare benign lesion of spleen with unknown etiology (Arch Pathol Lab Med 2013;137:1309)
  • Also called multinodular hemangioma
  • 2/3 women, mean age 48 years, range 30-60 years
  • Probably reactive, not neoplastic
  • May be splenic hamartomas which have undergone an unusual form of sclerosis, with a peculiar reactionary transformation of red pulp due to an exaggerated stromal response
Clinical features
  • Presents as asymptomatic splenic mass, abdominal pain or splenomegaly
Radiology images
  • Abdominal ultrasound, CT scans and MRI shows hypodense, sometimes multinodular splenic mass
  • CT or MRI with contrast cannot distinguish SANT from the surrounding spleen parenchyma
Prognostic factors
  • More aggressive if early age of onset
Case reports
  • Splenectomy is standard treatment
  • Indications for splenectomy included increase in mass size, marked splenomegaly, or lingering suspicion of malignancy
Clinical images

Well-circumscribed highly vascularised lesion

Expansible low density mass

5-cm tumor in hilus

Hypointensity of tumor

Splenic lesion at medial aspect

Lesion in lower spleen

Hypoenhancing mass

Solid tumor

Laparoscopic view

Gross description
  • Bosselated mass, solitary lesion, 3-17 cm, sharply demarcated from remaining spleen
  • Composed of coalescing red-brown nodules in dense fibrous stroma
Gross images

Well-defined nonencapsulated lesion

Well-demarcated, unencapsulated, dark brown mass

0.3–0.5 cm red-brown multinodular lesions

Splenic resection

Case of the Week #364

Microscopic (histologic) description
  • Micronodular appearance of slit-like, round or irregular shaped vascular spaces lined by plump endothelial cells with interspersed ovoid or spindle cells
  • Smaller nodules surrounded by concentric collagen fibers
  • Also numerous red blood cells
  • Stroma contains myxoid to dense fibrous tissue with scattered myofibroblasts, inflammatory cells
  • No/minimal atypia, no/rare mitotic figures, no necrosis
Microscopic (histologic) images

Angiomatoid nodules

Slit-like, round irregular-shaped vascular spaces

Concentric rims of collagen fibrils

CD31 highlights the abundant vascular structures

CD34 highlights the capillaries

CD8 highlights occasional sinusoid-like spaces

CD68 highlights scattered single cells

Case of the Week #364:

H&E images




Positive stains
  • 3 types of vessels:
    • Capillaries: CD34+/CD31+/CD8-
    • Sinusoids: CD34-/CD31+/CD8+
    • Small veins: CD34-/CD31+/CD8-
    • CD68 is positive in macrophages
Electron microscopy description
  • Small vascular spaces lined by endothelial cells with pinocytotic vesicles but no Weibel-Palade bodies