Concurrence of linear epidermal nevus and nevus flammeus in a man with optic pathway glioma: coincidence or phacomatosis?

Association of Schimmelpenning Syndrome with Astrocytoma (WHO Grade 3): Case Report

Schimmelpenning syndrome, or epidermal nevus syndrome, is a rare, neurocutaneous disorder characterized by skin abnormalities, such as epidermal nevi, and involvement of the central nervous system, including intracranial tumors. There are only a few reported cases of intracranial tumors associated with Schimmelpenning syndrome. In most cases, a single nucleotide mutation in the RAS family proto-oncogenes, like HRAS or KRAS genes, can result in the genetic mosaicism that is responsible for the clinical manifestations of this syndrome. The authors present a case report of a woman with Schimmelpenning syndrome who sought medical help with complaints of progressive headache and dizziness. The radiological and histopathological findings indicated an astrocytoma, IDH-mutant (WHO grade 3). The molecular analysis revealed pathogenic changes in the oncogenic HRAS gene with a prevalence of 31%. The patient underwent surgical treatment and had no neurological sequelae. By presenting such a clinical case, attention is paid to the interrelationship between genetic syndromes and intracranial tumors.

Is Schimmelpenning Syndrome Associated with Intracranial Tumors? A Case Report

Schimmelpenning syndrome is a rare, well-defined constellation of clinical phenotypes associated with the presence of nevus sebaceous and multisystem abnormalities most commonly manifested as cerebral, ocular, and skeletal defects [1]. A single nucleotide mutation in the HRAS or KRAS genes resulting in genetic mosaicism is responsible for the clinical manifestations of this syndrome in the majority of cases. We report a case of an adolescent boy with Schimmelpenning syndrome with a multifocal pilocytic astrocytoma. No HRAS or KRAS gene mutations were noted in the tumor on genetic sequencing. However, glial tumors have been associated with genetic mutations of RAS upregulation, which may imply a common pathway.

Cutaneous skeletal hypophosphatemia syndrome (CSHS) is a multilineage somatic mosaic RASopathy

BACKGROUND

We recently demonstrated multilineage somatic mosaicism in cutaneous skeletal hypophosphatemia syndrome (CSHS), which features epidermal or melanocytic nevi, elevated fibroblast growth factor (FGF)-23, and hypophosphatemia, finding identical RAS mutations in affected skin and bone.

OBJECTIVE

We sought to: (1) provide an updated overview of CSHS; (2) review its pathobiology; (3) present a new patient with CSHS; and (4) discuss treatment modalities.

METHODS

We searched PubMed for "nevus AND rickets," and "nevus AND hypophosphatemia," identifying cases of nevi with hypophosphatemic rickets or elevated serum FGF-23. For our additional patient with CSHS, we performed histopathologic and radiographic surveys of skin and skeletal lesions, respectively. Sequencing was performed for HRAS, KRAS, and NRAS to determine causative mutations.

RESULTS

Our new case harbored somatic activating HRAS p.G13 R mutation in affected tissue, consistent with previous findings. Although the mechanism of FGF-23 dysregulation is unknown in CSHS, interaction between FGF and MAPK pathways may provide insight into pathobiology. Anti-FGF-23 antibody KRN-23 may be useful in managing CSHS.

LIMITATIONS

Multilineage RAS mutation in CSHS was recently identified; further studies on mechanism are unavailable.

CONCLUSION

Patients with nevi in association with skeletal disease should be evaluated for serum phosphate and FGF-23. Further studies investigating the role of RAS in FGF-23 regulation are needed.