A Noonan-like pediatric patient with a de novo CBL pathogenic variant and an RNF213 polymorphism p.R4810K presenting with cardiopulmonary arrest due to left main coronary artery ostial atresia

Noonan syndrome-like disorder: Case report and review of the literature

Of patients with a Noonan syndrome phenotype, only about 1% are found to be related to pathological variants in CBL, also known as Noonan syndrome-like disorder (NSLD). We present a case of a 4-year-old boy diagnosed with NSLD, presenting with multiple melanocytic nevi and superficial neurofibromas. A literature review identified common cutaneous findings of NSLD, for example, café-au-lait macules (22%), juvenile xanthogranuloma (16%), and thin hair (10%). As there are no documented cases of neurofibromas associated with NSLD, and only a single report of multiple melanocytic nevi, inclusion of these features in the phenotype may be warranted and mitigate the necessity for future biopsies in other children.

Long-term remission of infantile Takayasu arteritis associated with germline CBL syndrome after allogeneic hematopoietic stem cell transplantation: A case report and literature review

Takayasu arteritis (TA) is a large-vessel vasculitis that rarely presents in infancy. Casitas B-lineage lymphoma (CBL) syndrome is a rare genetic disorder due to heterozygous CBL gene germline pathogenic variants that is characterized by a predisposition to develop juvenile myelomonocytic leukemia (JMML). Vasculitis, including TA, has been reported in several patients. Herein, we describe a patient with CBL syndrome, JMML, and TA, developing long-term remission of this vasculitis after allogeneic hematopoietic stem cell transplant (HSCT), and perform a literature review of CBL syndrome with vasculitis or vasculopathy. We report a female patient with growth delay, developmental issues, and congenital heart disease who was admitted at 14 months of age with massive splenomegaly, lymphadenopathy, fever, and hypertension. Body imaging studies revealed arterial stenosis and wall inflammation of the aorta and multiple thoracic and abdominal branches. Whole exome sequencing revealed a pathogenic variant in CBL with loss of heterozygosity in blood cells, diagnosing CBL syndrome, complicated by JMML and TA. Allogeneic HSCT induced remission of JMML and TA, permitting discontinuation of immunosuppression after 12 months. Six years later, her TA is in complete remission off therapy. A literature review identified 18 additional cases of CBL syndrome with vasculitis or vasculopathy. The pathogenesis of vasculitis in CBL syndrome appears to involve dysregulated T cell function and possibly increased angiogenesis. This case advances the understanding of vascular involvement in CBL syndrome and of the genetic, immune, and vascular interplay in TA, offering insights for treating CBL syndrome and broader TA.