European Journal of Cardiovascular Medicine

Sclerosing angiomatoid nodular transformation (SANT) of the spleen is a rare, benign, non-neoplastic vascular lesion. Fewer than 200 cases have been reported in the literature, and its exact incidence and prevalence remain uncertain. The entity was first described by Martel et al. in 2004, who characterized it as a distinctive benign vascular lesion well demarcated from the surrounding splenic parenchyma.

Grossly, SANT presents as coalescing red-brown nodules embedded within a dense fibrous stroma, giving a multinodular appearance on low-power microscopy. Histologically, the angiomatoid nodules consist of irregular, slit-like or round vascular spaces lined by plump endothelial cells and interspersed with spindle-shaped stromal cells. The nodules are often surrounded by concentric collagen fibers, with scattered inflammatory cells and hemosiderin-laden macrophages. Atypia and mitotic activity are minimal, and necrosis is absent.

Immunohistochemically, SANT demonstrates three distinct vascular profiles within the angiomatoid nodules: CD34⁺/CD8⁻/CD31⁺ capillaries, CD34⁻/CD8⁺/CD31⁺ sinusoids, and CD34⁻/CD8⁻/CD31⁺ small veins — a pattern that mimics the normal red pulp vasculature. These features distinguish SANT from other splenic vascular lesions, such as littoral cell angioma, conventional hemangioma, and hemangioendothelioma. The morphologic appearance, characteristic immunophenotype, and benign course support its interpretation as a non-neoplastic, reactive vascular process.

A 51-year-old woman presented with upper abdominal pain for eight days and fever for two days following minor blunt abdominal trauma from an accidental fall. On examination, there was tenderness in the epigastric region without guarding or rigidity.

Laboratory investigations revealed the following:

• Total leukocyte count: 6,600/mm³
• Platelet count: 1.86 × 10⁵/mm³
• Hemoglobin: 11.6 g/dL
• INR: 1.5
• Random blood sugar: 126 mg/dL
• Liver and renal function tests: within normal limits
• Viral markers: negative

Ultrasonography of the abdomen showed a normal-sized spleen (9.5 cm) with a well-defined, irregular, heterogeneously hypoechoic collection (4.7 × 5.4 × 4.4 cm) along the upper pole, suggestive of an organized lesion without peritoneal or diaphragmatic breach.

Contrast-enhanced computed tomography (CECT) of the abdomen demonstrated a mildly enhancing, well-circumscribed lesion in the upper and mid-pole of the spleen, measuring 4.2 × 5.4 × 4 cm. The lesion showed heterogeneous enhancement in the arterial and venous phases with non-enhancing areas centrally. There was no evidence of calcification, hemorrhage, or vascular invasion.

Figure 1:

After appropriate preoperative workup, the patient underwent elective laparoscopic splenectomy.

Gross examination of the resected spleen revealed a solitary, firm, gray-white mass (5 × 4 × 4 cm) centrally located and clearly demarcated from the surrounding splenic parenchyma. The cut surface showed multiple peripheral nodules resembling hemangiomatous areas.

Figure 2

Histopathological examination showed multiple variably sized angiomatoid nodules separated by dense sclerotic stroma with mixed inflammatory infiltrates. The nodules comprised irregular vascular channels containing intravascular and extravasated red blood cells. Adjacent splenic parenchyma revealed sinusoidal congestion. These findings were diagnostic of sclerosing angiomatoid nodular transformation of the spleen.

Figure 3:

The postoperative course was uneventful. The patient received routine post-splenectomy vaccinations (pneumococcal, meningococcal, and Haemophilus influenzae type b) and was discharged on postoperative day 5 in stable condition. She remains asymptomatic on follow-up.

Among benign splenic lesions, hemangioma is the most common, followed by hamartoma and littoral cell angioma. SANT was initially misclassified under these categories and variably described as “splenic cord capillary hemangioma” or “multinodular hemangioma.” Silverman and LiVolsi (1978) first reported such lesions as splenic hamartomas, and later Falk et al. (1993) referred to them as “splenic cord capillary angioma.” Martel et al. subsequently redefined SANT as a distinct clinicopathological entity.

Radiologically, SANT often appears as a well-circumscribed, hypointense lesion on non-contrast CT, with progressive, centripetal “spoke-wheel” enhancement after contrast administration — a feature also demonstrable on MRI. Despite these imaging characteristics, differentiation from other splenic lesions such as lymphoma, metastasis, or angiosarcoma remains difficult preoperatively. Therefore, definitive diagnosis requires histopathological and immunohistochemical correlation.

The pathogenesis of SANT remains uncertain, though reactive or inflammatory processes involving the red pulp vasculature have been proposed. The benign clinical course and absence of recurrence or metastasis support this hypothesis.

Sclerosing angiomatoid nodular transformation is an uncommon, benign vascular lesion of the spleen that poses a diagnostic challenge due to nonspecific clinical and radiologic findings. Histopathological and immunohistochemical evaluation are essential for confirmation. Splenectomy remains the treatment of choice, serving both diagnostic and curative purposes.

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