Patterns of infantile hemangiomas: New clues to hemangioma pathogenesis and embryonic facial development

OBJECTIVES. Large facial infantile hemangiomas have higher rates of complications than small localized hemangiomas, more often require treatment, and can be associated with neurological, ophthalmologic, and cardiac anomalies (PHACE syndrome). The anatomic patterns of these hemangiomas are often referred to as '' segmental '' despite a lack of precise anatomic definitions. Our study aims to define '' segmental '' hemangiomas based on clinically observed patterns. Our secondary goal is to relate the observed patterns to currently accepted developmental patterns to gain insight into hemangioma pathogenesis and craniofacial development. METHODS. Photographic data were extracted from a large cohort of patients with infantile hemangiomas. We mapped 294 hemangiomas and recorded common morphologic patterns. Anatomic descriptions of the most common patterns were described and compared with accepted concepts of craniofacial development. RESULTS. Four primary segments were identified (Seg1-Seg4). Seg2 and Seg3 correspond with the previously recognized maxillary and mandibular prominences. Seg1 and Seg4 differ from standard human embryology texts. The frontotemporal segment, Seg1, encompasses the lateral forehead, anterior temporal scalp, and lateral frontal scalp. The segment Seg4, encompassing the medial frontal scalp, nasal bridge, nasal tip, ala, and philtrum, is substantially narrower on the forehead than the previously described frontonasal prominence. CONCLUSIONS. The patterns provide new clues regarding facial development. The observed patterns resemble previously described facial developmental units on the lower face but are distinctly different on the upper face. The patterns suggest that neural crest derivatives may play a role in the development of facial hemangiomas. Finally, these patterns (Seg1-Seg4) help standardize the nomenclature of facial segmental hemangiomas to analyze more effectively hemangioma risks and behavior.