Concurrent Juvenile Myelomonocytic Leukemia and Gliomas in Patients With Neurofibromatosis Type 1.

Neurofibromatosis 1 (NF1) is the most common cancer predisposition syndrome and is characterized by a wide range of clinical manifestations, including increased risk of developing various types of malignancies. We report nine patients with NF1 who presented with concurrent diagnoses of juvenile myelomonocytic leukemia and low-grade glioma, a rare combination. One notable feature of this cohort is that eight patients (89%) harbored nonsense germline NF1 variants. This case series highlights the emergence of synchronous or metachronous malignancies in children with NF1 and provides a rationale for heightened awareness of this phenomenon.