Mapping of Segmental and Partial Segmental Infantile Hemangiomas of the Face and Scalp.

Importance: Recognizing segmental infantile hemangioma (IH) patterns is important for risk stratification and provides clues to pathogenesis. Previously, segmental hemangiomas were mapped to 4 facial regions, 3 corresponding to known facial metameres.
Objectives: To refine existing maps of facial segmental IHs, examine so-called indeterminate hemangiomas as they relate to known segmental patterns, and define a novel pattern of segmental scalp hemangiomas.
Design, Setting, and Participants: This retrospective cohort study was conducted at 4 pediatric dermatology centers (University of California, San Francisco; Indiana University; Medical College of Wisconsin; and Northwestern University/Ann & Robert H. Lurie Children's Hospital of Chicago) using photographic archives of patients younger than 12 years with segmental and indeterminate hemangiomas on the face and scalp. Clinical images were used to map hemangioma distribution onto standardized facial templates. Heat map densiometry identified recurrent patterns that were compared with previously published patterns of facial segmental hemangiomas. Patterns of indeterminate hemangiomas were compared with those of segmental hemangiomas. Data collection took place in 2017, and analysis took place from 2017 to 2019.
Main Outcomes and Measures: Distribution and patterning of segmental and indeterminate IHs of the face and scalp.
Results: A total of 549 IHs were mapped. The borders of the frontotemporal (S1) and frontonasal (S4) segments agreed with previous segmental maps; however, the maxillary (S2) and mandibular (S3) segment borders differed with respect to the preauricular skin. In contrast with previous reports, preauricular skin segregated with the mandibular (S3) rather than the maxillary (S2) segment. Indeterminate hemangiomas occurred within and respected the same borders as segmental hemangiomas. Hemangiomas on the lateral scalp commonly occurred in a C shape extending from the posterior auricular region.
Conclusions and Relevance: This cohort study provides an updated map of facial segmental IHs with redefined maxillary (S2) and mandibular (S3) segment borders. It provides evidence that indeterminate hemangiomas are partial segmental hemangiomas respecting anatomic boundaries of their larger segmental counterparts. A newly recognized C-shaped pattern of segmental scalp hemangioma is reported.