Rhabdomyosarcoma as the first presentation in Neurofibromatosis Type 1: case series and review of the literature.

Neurofibromatosis Type 1 (NF1) is a neurocutaneous syndrome characterized by multiple café-au-lait macules, neurofibromas, and predisposition to malignancies, including rhabdomyosarcomas (RMS). Somatic NF1 mutations occur in RMS and other cancers, and ∼1% of patients with RMS have NF1. We describe three patients who presented prior to one year of age with RMS and were subsequently diagnosed with NF1. Compared to sporadic RMS, patients with this cancer predisposition syndrome are diagnosed younger, genitourinary sites are more common, and tumors are almost exclusively the embryonal subtype. Genomic sequencing of the tumor was initiated in one patient, and we identified a second sequence variant in NF1. The identification of molecular drivers in tumors is changing the nature of pediatric oncology by informing therapeutics targeted to specific molecular pathways and selecting patients who are likely to harbor germline variants in cancer predisposition genes who would benefit from a Medical Genetics assessment.

Porokeratotic eccrine ostial and dermal duct nevus associated with an 11 megabase 3p deletion.

Porokeratotic eccrine ostial and dermal duct nevus (PEODDN) is a rare eccrine hamartoma; the etiology is incompletely understood. A patient presented with congenital, widespread PEODDN. Clinical assessment, histopathologic, cytogenetic, and molecular genetic investigations on affected cells were pursued. Histopathology confirmed PEODDN, and chromosomal microarray on affected tissues identified a mosaic 3p26.3p25.3 deletion in affected tissues. This 11Mb deletion encompasses 47 OMIM genes. We propose that this and other chromosomal deletions may be implicated in some cases of PEODDN, suggesting locus heterogeneity and underscoring the importance of incorporating cytogenetic and molecular investigations into the multidisciplinary care of individuals with suspected mosaic genetic skin disorders.