A fraction of deep vascular birthmarks are true deep hemangiomas of infancy

Background: Deeply-located vascular birthmarks have been traditionally regarded as being identical to a deep type of hemangioma of infancy (HOI). However, there is increasing evidence that some venous malformations also mimic these deep type of HOIs clinically. This study investigates how many, if not all, deep vascular birthmarks are deep type HOIs. Methods: Nineteen cases were selected on the basis of the clinical features of deeply-located vascular birthmarks. Hematoxylin-eosin slides were reviewed and immunohistochemistries were performed using CD31, D2-40 and GLUT1 to confirm diagnoses before they were compared with the clinicoradiologic review by specialists other than dermatopathologists. Results: Only 4 patients out of a total of 19 cases were strongly positive for GLUT1 staining and turned out to be true deep HOIs. The remaining were comprised of 6 venous malformations (31.6%), 3 lymphatic malformations (15.8%), 1 glomangioma (5.35%) and 5 tufted angiomas (26.3%). Conclusions: It was demonstrated that all deeply-located vascular birthmarks are not true deep HOIs. It is recommended that diagnosis for HOI be carried out cautiously earlier in life using GLUT1 in addition to clinical features. This would help prevent patients from being misled by anticipating the spontaneous involution in all deeply-located vascular birthmarks.