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Rapidly involuting congenital hemangioma; congenital hemangioma; congenital non-progressive hemangioma.
Rapidly involuting congenital hemangioma is a rare benign tumor similar to infantile hemangioma. Its name comes from its particular natural course: it is fully developed at birth and then completely involutes, usually in the first year . These congenitally fully developed lesions have generally been assumed to be clinical variants of more typical, postnatally developing hemangiomas . While infantile hemangiomas are a very common lesion seen in infants and young children, congenital hemangiomas are rare. Two types of congenital hemangiomas exist: rapidly involuting congenital hemangiomas and noninvoluting congenital hemangiomas .
Hemangiomas are the most common tumors of infancy. Infantile hemangiomas occur in 4% to 10% of white infants, and they are 3 to 5 times more commonly seen in female infants, most frequently in whites and less commonly in those of African or Asian descent . Congenital hemangiomas are much more rare.
Pathogenesis of congenital hemangiomas is not very well understood. Some authors believe that they could originate from either invading angioblasts that differentiate toward a placental phenotype or form embolized placental cells. Erythrocyte type glucose transporter isoform 1 (GLUT1), a glucose transporter enzyme, is uniquely expressed on endothelial cells of hemangiomas but not in surrounding normal vascular endothelium . Lymphatic endothelial hyaluronan receptor-1 (LYVE-1), a specific marker for normal and tumor-associated lymphatic vessels, was strongly expressed in tumor cells of infantile hemangiomas but was absent during involution. That is why some authors believe that endothelial cells in proliferating infantile hemangioma are arrested in an early developmental stage of vascular differentiation . Some overlapping clinical and pathologic features can be found among rapid involuting congenital hemangiomas, non-involuting congenital hemangiomas and infantile hemangiomas. These observations support the hypothesis that these vascular tumors may be variations of a single entity ab initio, but it is unknown whether the progenitor cell for these uncommon congenital vascular tumors is the same as for common infantile hemangioma .
Usually hypoechoic lesions mostly confined to the subcutaneous fat with diffuse vasculature. Some of the vessels show a venous flow signal, while others demonstrated low resistant arterial flow . Large and irregular feeding arteries are in disorganized patterns, arterial aneurysms, direct arteriovenous shunts, and intravascular thrombi are present . Sonographically detectable hemangiomas are usually of the cavernous type, which involve not only cutaneous vessels but also larger venous sinusoids in the deep dermis and subcutaneous tissues. The most common appearance is that of a solid mass with an echotexture similar to placenta, but cystic hemangiomas have also been reported . Hemangiomas do not change bony anatomy in the region.
Images 1, 2. Transverse sections through the skull showing tumor (hemangioma) in nuchal region with rich vascularisation.