CBL Syndrome With Granular Cell Tumor and café au lait macules: Expansion of the Phenotype

CBL syndrome is a RASopathy with phenotypic variability including neurodevelopmental differences, cardiac defects, growth delay, dysmorphic and cutaneous findings, hematologic, immunologic, and vascular manifestations, and predisposition to juvenile myelomonocytic leukemia (JMML). We present a patient with a germline likely pathogenic variant in CBL with ten café au lait macules and a recurrent granular cell tumor. Granular cell tumors have not been described in this condition. This case broadens the recognized clinical spectrum of CBL syndrome and challenges the existing genetic testing approach for patients with greater than six café au lait macules.