Figure 1
Teaching Case
SectionAbdominal imaging
Case TypeClinical Cases
Authors
Savastano S1, Famengo B2, Costantini A1, Trupiani S2, D’Amore E2
Department of Radiology1 and Pathology2, Ospedale San Bortolo, Vicenza, Italy
Connected authors
64 years, male
An asymptomatic 64-year-old man was evaluated with an abdominal CT because of a splenic mass incidentally detected at an ultrasonographic examination of the abdomen. His past history was unremarkable except for an endoscopic resection of an in situ cancer of the bladder. Routine laboratory tests were within normal limits.
Sclerosing angiomatoid nodular transformation of the spleen
Haemangioma
Hamartoma
Littoral cell angioma
Haemangiopericytoma
Lymphoma
Metastases
CT examination showed a round 3.5-cm-diameter mass of the spleen iso-hypoattenuating on non-enhanced images. The mass was hypoattenuating in the arterial phase, inhomogeneously enhancing in the portal phase and isoattenuating in the equilibrium phase (Fig.1). No other abnormalities were detected on CT examination. F-18 FDG CT-PET demonstrated a moderate activity of the splenic mass (standard uptake value 3.4) (Fig. 2). Because of the indeterminate nature of the mass, a laparoscopic splenectomy was undertaken. The operation was uneventful and the patient is in good conditions after two-year-follow up. Grossly the lesion was a nodular mass with fibrotic appearance encompassing brownish nodules (Fig. 3a). Microscopically the nodules were composed of vessels lined by endothelial cells, ovoid-spindle cells and extravasated erythrocytes (Fig. 3b). A dense hypocellular fibrous stroma separated the nodules. CD34 and CD31 immunostaining highlighted the vascular and single cells components.
Sclerosing angiomatoid nodular transformation (SANT) of the spleen is a rare recently described vascular entity of unknown origin with peculiar pathological and immunohistochemical features [1]. Pathogenetic hypothesis relies on an abnormal red pulp response to an exaggerated stromal proliferation due to disruption of small vascular outflow tracts, inducing vascular transformation of lymphatic sinuses [1,2]. SANTs of the spleen are frequently associated with neoplasms, leukemia, abdominal calcifying fibrous tumours or chronic diseases [1,2]. Lesions can be solitary or multicentric and variable in size, up to 9 cm in diameter [3]. Natural history is unknown, but increasing in size can be observed in follow up studies [4,5]. The SANT of the spleen can be asymptomatic and incidentally detected, but patients can complain of non-specific abdominal pain and discomfort or splenomegaly [1,2,4]; outcome is favourable after splenectomy [1,2,4,5].
The SANT of the spleen sonographically appears as a heterogeneous hypoechoic nodule or as isoechoic mass surrounded by a hypoechoic rim [6-8]; contrast-enhanced ultrasonography can show a diffuse enhancement or a spoke wheel enhancing pattern [7,8].
The SANT is hypo-isoattenuating on non-enhanced CT, sometimes with a central nodular calcification [3-5,9-12]. On dynamic CT the lesion can show different patterns: no definitive enhancement, hypoattenuation or inhomogeneous hyperattenuation in the arterial phase with a progressive centripetal enhancement in the portal phase with or without a spoke wheel pattern; on delayed images the SANT appears isoattenuating to the spleen, but larger masses can show a central scar [3,5-7,9-12].
Signal of the SANT is usually heterogeneously hypointense on T1 and T2 weighted MRI; a haemorrhagic component can sometimes be demonstrated [3,4,10,11,13].
Enhancement pattern on dynamic MRI resembles pattern of dynamic CT, but it seems more sensitive in detecting a radiating enhancement [3,11].
The SANT of the spleen shows a hypermetabolic activity with F18-FDG PET-CT, but it does not exhibit a macrophagic activity with 99mTC-sulfur colloid [3,4,6].
Since percutaneous biopsy of the spleen is not a popular procedure among radiologists, and because of uncertainties of imaging findings, diagnosis of a SANT of the spleen is usually achieved after splenectomy. Nevertheless radiologist should become familiar with this new entity, which should be considered in the differential diagnosis of splenic nodules; a spoke wheel pattern on dynamic imaging may suggest the proper diagnosis.
The SANT of the spleen sonographically appears as a heterogeneous hypoechoic nodule or as isoechoic mass surrounded by a hypoechoic rim [6-8]; contrast-enhanced ultrasonography can show a diffuse enhancement or a spoke wheel enhancing pattern [7,8].
The SANT is hypo-isoattenuating on non-enhanced CT, sometimes with a central nodular calcification [3-5,9-12]. On dynamic CT the lesion can show different patterns: no definitive enhancement, hypoattenuation or inhomogeneous hyperattenuation in the arterial phase with a progressive centripetal enhancement in the portal phase with or without a spoke wheel pattern; on delayed images the SANT appears isoattenuating to the spleen, but larger masses can show a central scar [3,5-7,9-12].
Signal of the SANT is usually heterogeneously hypointense on T1 and T2 weighted MRI; a haemorrhagic component can sometimes be demonstrated [3,4,10,11,13].
Enhancement pattern on dynamic MRI resembles pattern of dynamic CT, but it seems more sensitive in detecting a radiating enhancement [3,11].
The SANT of the spleen shows a hypermetabolic activity with F18-FDG PET-CT, but it does not exhibit a macrophagic activity with 99mTC-sulfur colloid [3,4,6].
Since percutaneous biopsy of the spleen is not a popular procedure among radiologists, and because of uncertainties of imaging findings, diagnosis of a SANT of the spleen is usually achieved after splenectomy. Nevertheless radiologist should become familiar with this new entity, which should be considered in the differential diagnosis of splenic nodules; a spoke wheel pattern on dynamic imaging may suggest the proper diagnosis.
References
[1] Martel M, Cheuk W, Lombardi L, et al (2004) Report of 25 Cases of a Distinctive Benign Splenic Lesion. Am J Surg Pathol 28:1268–1279 (PMID: 15371942)
[2] Kuo TT, Chen TC, Lee LL (2009) 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. Pathol Int 59:844–850 (PMID: 20021608)
[3] Thacker C, Korn R, Millstine J et al (2009) Sclerosing angiomatoid nodular transformation of the spleen: CT, MR, PET, and 99mTc-sulfur colloid SPECT CT findings with gross and histopathological correlation. Abdom Imaging 35:683-689 (PMID: 19862569)
[4] Koreishi AF, Saenz AJ, Fleming SE, Feldstein JT (2009) Sclerosing Angiomatoid Nodular Transformation (SANT) of the Spleen: A Report of 3 Cases. Int J Surg Pathol 17:384-389 (PMID: 19666947)
[5] Langer R, Dinges J, Dobritz M, et al (2009) Sclerosing angiomatoid nodular transformation of the spleen presenting as a rapidly growing tumour in a patient with rectal cancer. BMJ Case Reports doi:10.1136/bcr.11.2008.1191
[6] Lee D, Wood B, Formby M, Cho T (2007) F-18 FDG-avid sclerosing angiomatoid nodular transformation (SANT) of the spleen: case study and literature review. Pathology 39:181-183 (PMID: 17365838)
[7] Gutzeit A, Stuckmann G, Dommann-Scherrer C (2009) Sclerosing angiomatoid nodular transformation (SANT) of the spleen: sonographic finding. J Clin Ultrasound 37:308–311 (PMID: 19170123)
[8] Cao JY, Zhang H, Wang WP (2010) Ultrasonography of sclerosing angiomatoid nodular transformation in the spleen. World J Gastroenterol 16:3727-3730 (PMID: 20677348)
[9] Li L, Fisher DA, Stanek AE (2005) Sclerosing angiomatoid nodular transformation (SANT) of the Spleen: addition of a Case with focal CD68 staining and distinctive CT features. Am J Surg Pathol 29:839-841 (PMID: 15897756)
[10] Lee JC, Lien HC, Hsiao CH (2007) Coexisting sclerosing angiomatoid nodular transformation of the spleen with multiple calcifying fibrous pseudotumors in a patient. J Formos Med Assoc 106:234–239 (PMID: 17389168)
[11] Karaosmanoglu DA, Karcaaltincaba M, Akata, D (2008) CT and MRI findings of sclerosing angiomatoid nodular transformation of the spleen: spoke wheel pattern. Korean J Radiol 9:S52-S55 (PMID: 18607127)
[12] Zeeb LM, Johnson JM, Madsen MS, Keating DP (2009) Sclerosing angiomatoid nodular transformation. AJR 192:W236-238 (PMID: 19380529)
[13] Chikkappa MG, Morrison C, Lowe A, et al. (2009) Case report and magnetic resonance images of sclerosing angiomatoid nodular transformation (SANT) of the spleen. BMJ Case Reports doi:10.1136/bcr.07.2009.2131
Case information
| URL: | https://eurorad.org/case/9426 |
| DOI: | 10.1594/EURORAD/CASE.9426 |
| ISSN: | 1563-4086 |
Figure 2
