Infantile hemangiomas (IHs) are the most common tumors of childhood. Unlike other tumors, they have the unique ability to involute after proliferation, often leading primary care providers to assume they will resolve without intervention or consequence. Unfortunately, a subset of IHs rapidly develop complications, resulting in pain, functional impairment, or permanent disfigurement. As a result, the primary clinician has the task of determining which lesions require early consultation with a specialist. Although several recent reviews have been published, this clinical report is the first based on input from individuals representing the many specialties involved in the treatment of IH. Its purpose is to update the pediatric community regarding recent discoveries in IH pathogenesis, treatment, and clinical associations and to provide a basis for clinical decision-making in the management of IH.

Objective To identify features associated with multisystem involvement and therapeutic failure in patients with skin Langerhans cell histiocytosis (LCH). Study design We reviewed medical records of 71 consecutive LCH patients with skin involvement evaluated at Texas Children’s Hospital and analyzed clinical features, laboratory results, and presence of circulating cells with the BRAF-V600E mutation, with respect to initial staging and clinical outcomes. Results Skin disease in patients older than 18 months at diagnosis was associated with presence of multisystem disease (OR 9.65, 95% CI 1.17–79.4). Forty percent of patients referred for presumed skin-limited LCH had underlying multisystem involvement, half of these with risk-organ involvement. Patients with skin-limited LCH had 3-year progression-free survival (PFS) of 89% after initial therapy, and none developed multisystem disease. Patients with skin/multisystem involvement had 3 year PFS of 44% with vinblastine/prednisone therapy, and risk-organ involvement did not correlate with failure to achieve non-active disease. Circulating cells with BRAF-V600E were detected at higher frequency in multisystem patients (8/11 skin/multisystem, 1/13 skin-limited, P=0.002). Conclusions Skin-limited LCH requires infrequent therapeutic intervention and has lower risk of progression relative to skin plus multisystem LCH. The less aggressive clinical course and lack of circulating cells with BRAF-V600E mutation in skin-limited LCH suggest a different mechanism of disease origin compared with multisystem or risk-organ disease.

BACKGROUND: Childhood melanocytic tumors represent a diagnostic and therapeutic challenge, and additional research is needed to better define the natural history of these tumors. METHODS: The authors developed a comprehensive, prospective registry called Molecular Analysis of Childhood Melanocytic Tumors for children and adolescents with an atypical Spitz tumor/Spitz melanoma (AST/ SM), conventional or adult-type melanoma (CM), melanoma arising in a giant congenital nevus (MCM), or atypical melanocytic proliferation of other types (OT) to better define the clinical behavior of these lesions by incorporating an integrated clinicopathologic and molecular analysis using centralized pathology review and various platforms, including fluorescence in situ hybridization; array comparative genomic hybridization; and whole genome, exome, and capture targeted panels. RESULTS: From May 2016 to November 2019, 70 children were enrolled with a median age at diagnosis of 9.1 years. Thirty-seven had AST/SM, 17 had CM, 4 had MCM, and 12 had OT. Patients with AST/SM were younger (median age, 7 years), and their tumor most commonly arose in the extremities and trunk. The most common gene rearrangements included MAP3K8 and ALK. None of the 33 patients who underwent a TERT promoter mutation analysis had a mutation, and all patients were alive. Among the CM patients, the median age was 13 years; 11 had a BRAFV600E mutation, and 7 had a TERT promoter mutation. Three patients died of their disease. All 4 patients with MCM harbored an NRASQ61 mutation and died of their disease. The OT group was heterogenous, and all patients survived. CONCLUSIONS: The incorporation of an integrated clinicopathologic and genomic analysis identifies distinct subgroups of pediatric melanocytic lesions that have different clinical behaviors. The integration of this combined diagnostic modality can help to individualize diagnoses and treatments for these patients.

Capsule Summary The authors identify Natural Killer cell deficiency in post-transplant severe combined immunodeficiency patients who developed severe human papilloma virus infections as a long term complication.