2.1 Introduction

Congenital vascular masses may be benign or malignant and are reviewed in this chapter. Vascular lesions that are present at birth may also be detected antenatally via routine ultrasound examination, with further assessment by fetal magnetic resonance imaging if considered necessary. Serial monitoring is necessary to maintain a safe pregnancy and to evaluate flow characteristics, fetal growth or compromise, and size of the abnormality, all of which contribute to rational decision making regarding the timing and type of delivery. In some cases, the affected fetus has been treated medically by transplacental passage of medication administered to the mother (e.g., corticosteroids for high-flow hepatic hemangiomatosis, digoxin for a high-flow congenital hemangioma of the nape ( Fig. 2.1 ).

Whereas “typical” hemangiomas are not apparent at birth and proliferate postnally, rapidly involuting congenital hemangioma (RICH) lesions are present prenatally and gradually involute after birth ( Fig. 2.2 ). ^{1 ,​ 2 ,​ 3 ,​ 4 ,​ 5} The clinical features of the subtypes of hemangiomas are summarized in Table 2.1 . Some RICH lesions are very high flow, even in utero, and can cause a high-output state and fetal or infant distress. Transient thrombocytopenia may also be present postnatally and self-resolves. ^{6 ,​ 7 ,​ 8} Many RICH lesions have a circumferential pale “halo.” Most do not require therapy and improve naturally; however, the subgroup with a symptomatic high-flow component may benefit from embolization. Lesions that ulcerate require medical and local attention. RICHs are often on the nape, scalp, or extremities and have characteristic radiologic findings, with less well-defined margins than typical hemangiomas and high flow, ^{9 ,​ 10 ,​ 11 ,​ 12} and they are benign histologically, typically with plump lobular endothelial cells, which are typically GLUT-1 negative.

Noninvoluting congenital hemangiomas (NICHs), also termed congenital nonprogressive hemangiomas, are histologically and immunophenotypically distinctive from typical hemangiomas of infancy and RICH and are considered to have a differing pathogenesis. ^{13 ,​ 14} They are present at birth and do not involute. On Doppler ultrasound, NICH-type lesions may have high flow clinically. ¹² Histologically benign, these are glucose transporter type 1 (GLUT1) negative and have thin-walled, lobular endothelial cells with arterial shunting.