Sclerosing angiomatoid nodular transformation (SANT), cord capillary haemangioma, multinodular haemangioma

Definition

Epidemiology

SANT is a splenic lesion of adults, more common in women.

Clinical features

The lesion presents as an asymptomatic splenic mass or with abdominal pain. Some cases are associated with fever, leukocytosis, polyclonal gammopathy or raised ESR. Identical changes to SANT may occur in proximity to metastatic adenocarcinoma or sarcoid.

Macroscopic appearances

There is a single circumscribed mass. The cut surface is fibrotic, with multiple red-brown nodules. Necrosis is absent.

Histopathology

There are multiple angiomatoid nodules within a fibrotic stroma. The angiomatoid nodules consist of slit-like, round or irregular vascular spaces lined by plump endothelial cells. Variable numbers of mononuclear inflammatory cells are present. Atypia and mitotic activity are lacking. The fibrotic areas are hyalinised and may calcify.

Immunohistochemistry

Three different types of blood vessels are present:

	normal equivalent	CD34	CD31	CD8
narrow well-formed capillaries in a lobular pattern	cord capillaries	+	+	-
open vascular spaces	sinusoids	-	+	+
a complex meshwork of vascular spaces and single cells	small veins	-	+	-

All vessels are negative for CD21, CD35 and CD68.

SMA, CD31 and CD68 stain conglomerates of spindle cells between the vessels. Desmin, CD21 and CD35 are negative.

Ultrastructure

The endothelial cells have pinocytotic vesicles but lack Weibel Palade bodies.

Differential diagnosis

Haemangioma: composed of a single type of vessel. Vessels are often cavernous and are identical to those found in soft tissues. They do not form angiomatoid nodules. They are usually CD31+/CD34+/CD8-.
Littoral cell angioma: composed of a single type of vessel, corresponding to sinusoidal lining cells. It forms multiple separate nodules. The lining cells are plump and may form pseudopapillae. Sclerosis is lacking. The cells are CD31+/CD34-/CD8-.
Hamangioendothelioma is very rare in the spleen. The cells show atypia.
Splenic hamartoma is composed of disorganized red pulp. The margins are poorly defined. An angiomatoid nodular pattern is lacking.
Inflammatory pseudotumour appears identical to the internodular zones of SANT.

Management

Prognosis

The clinical course is benign, all cases being cured by splenectomy.

References

Martel, M., W. Cheuk, et al. (2004). "Sclerosing angiomatoid nodular transformation (SANT): report of 25 cases of a distinctive benign splenic lesion." Am J Surg Pathol 28(10): 1268-79.

This page last revised 2.11.2004.