The only recently described entity sclerosing angiomatoid nodular transformation (SANT) of the spleen, a non-neoplastic vascular entity described and named in 2004 5 may be a fibrosing variant of splenic hamartoma 6.
Splenic hamartomas are very rare with only 3 described in a series of 200 000 splenectomies.
Hamartomas are normally an incidental finding at imaging, surgery or autopsy. They can occur in any age group. Symptoms occur from mass effect if they grow large.
Hamartomas are solitary or multiple, round, well-circumscribed, unencapsulated bulging nodules compressing the adjacent normal splenic parenchyma. Focal fibrosis and cystic areas can be seen.
The pathological differential diagnosis includes haemangioma, Littoral cell angioma, lymphagioma, haemangioendothelioma, sclerosing angiomatoid nodular transformation (see above), angiosarcoma. A definite diagnosis can be difficult due to overlap of features, however positivity of CD8 is a key feature that differentiates hamartoma from other vascular lesions of the spleen.
Most splenic hamartomas are hyperechoic solid masses, with or without cystic changes in ultrasonogram, and are hypervascular in both colour Doppler ultrasound and angiogram.
On computed tomography, hamartomas appear as isodense or hypodense solid masses and demonstrate heterogeneous contrast enhancement relative to adjacent normal parenchyma.
MRI is the preferable imaging technique for its distinction from haemangiomas.
- T1: most lesions are isointense
- T2: most lesions are heterogeneously hyperintense
dynamic enhanced MRI
- it is typical to show faint heterogeneous enhancement on immediate postcontrast-enhanced images (key features in the differentiation between hamartomas and hemangiomas)
- on delayed postcontrast images, hamartoma enhances in a relatively uniform and intense fashion +/- with central hypovascular areas
- normal appearance of the spleen
- pseudolesion of the spleen: inhomogeneous splenic enhancement
splenic lesions and anomalies
- congenital anomalies
- mass lesions
- infiltrative processes
- incidental splenic lesion (approach)
- 1. Lee H, Maeda K. Hamartoma of the spleen. Arch. Pathol. Lab. Med. 2009;133 (1): 147-51. doi:10.1043/1543-2165-133.1.147 - Pubmed citation
- 2. Abbott RM, Levy AD, Aguilera NS et-al. From the archives of the AFIP: primary vascular neoplasms of the spleen: radiologic-pathologic correlation. Radiographics. 2004;24 (4): 1137-63. Radiographics (full text) - doi:10.1148/rg.244045006 - Pubmed citation
- 3. Luna A, Ribes R, Caro P et-al. MRI of focal splenic lesions without and with dynamic gadolinium enhancement. AJR Am J Roentgenol. 2006;186 (6): 1533-47. doi:10.2214/AJR.04.1249 - Pubmed citation
- 4. Walczyk J, Walas MK. Standards of the Polish Ultrasound Society- update. Spleen examination. J Ultrason 2013; 13: 50-64.
- 5. Martel M, Cheuk W, Lombardi L et-al. Sclerosing angiomatoid nodular transformation (SANT): report of 25 cases of a distinctive benign splenic lesion. Am. J. Surg. Pathol. 2004;28 (10): 1268-79. Pubmed citation
- 6. Falk GA, Nooli NP, Morris-Stiff G et-al. Sclerosing Angiomatoid Nodular Transformation (SANT) of the spleen: Case report and review of the literature. Int J Surg Case Rep. 2012;3 (10): 492-500. doi:10.1016/j.ijscr.2012.06.003 - Free text at pubmed - Pubmed citation