Splenic hamartomas are very rare lesions commonly found incidentally on imaging. They are most often solitary but may be present as multiple nodules in patients with tuberous sclerosis or Wiskott-Aldrich syndrome.
The recently-described sclerosing angiomatoid nodular transformation (SANT) of the spleen, a non-neoplastic vascular entity 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 and compounded by a mixture of normal splenic structures such as white and red pulp. Focal fibrosis and cystic areas can be seen.
The pathological differential diagnosis includes hemangioma, Littoral cell angioma, lymphangioma, hemangioendothelioma, sclerosing angiomatoid nodular transformation (see terminology), angiosarcoma. A definite diagnosis can be difficult due to the overlap of features, however, positivity for CD8 is a key feature that differentiates hamartoma from other vascular lesions of the spleen.
As hamartomas represent a focal disorganized overgrowth of splenic parenchyma, they tend to have similar echogenicity, attenuation, and signal intensity to the background normal parenchyma 7.
Most splenic hamartomas are hypoechoic solid masses but can be heterogeneous due to hemorrhage or cystic changes 7. They are hypervascular on color Doppler ultrasound and post-contrast administration.
On computed tomography, hamartomas appear as isodense or hypodense solid masses and demonstrate heterogeneous contrast enhancement relative to the adjacent normal parenchyma.
MRI is the preferred imaging technique for the differentiation of hamartomas from hemangiomas, showing:
- T1: most lesions are isointense
- T2: most lesions are heterogeneously hyperintense
T1 C+ (Gd):
- it is typical to show vivid enhancement on immediate post-contrast 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
Possible differential considerations include
- 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. (2013) Journal of ultrasonography. 13 (52): 50-64. doi:10.15557/JoU.2013.0004 - Pubmed
- 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
- 7. Lee HJ, Kim JW, Hong JH, Kim GS, Shin SS, Heo SH, Lim HS, Hur YH, Seon HJ, Jeong YY. Cross-sectional Imaging of Splenic Lesions: RadioGraphics Fundamentals | Online Presentation. (2018) Radiographics : a review publication of the Radiological Society of North America, Inc. 38 (2): 435-436. doi:10.1148/rg.2018170119 - Pubmed
- 8. J Sim, H In Ahn, H Han et al. Splenic hamartoma: A case report and review of the literature. (2013) World Journal of Clinical Cases. 1 (7): 217. doi:10.12998/wjcc.v1.i7.217 - Pubmed
Related Radiopaedia articles
- 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)