Neurocutaneous melanosis presenting with hydrocephalus and malignant transformation: case-based update

Area of Science:

• Neurology
• Dermatology
• Pediatrics

Background:

• Neurocutaneous melanosis (NCM) is a rare congenital disorder characterized by congenital melanocytic nevi and leptomeningeal melanosis.
• It results from congenital dysplasia of melanin-producing cells in the skin and leptomeninges.
• Management of cutaneous and neurological manifestations remains challenging with poor outcomes for neurological involvement.

Observation:

• A 5-month-old boy with a giant congenital melanocytic nevus and hydrocephalus presented with confirmed leptomeningeal melanosis.
• The patient underwent ventriculoperitoneal shunt placement for hydrocephalus and received trametinib.
• Despite initial improvement, the patient later developed neurological deterioration, succumbing to malignant transformation of leptomeningeal disease.

Findings:

• Diagnosis of NCM was based on MR imaging, CSF cytology, and clinical presentation.
• Symptomatic NCM is refractory to conventional treatments like radiotherapy and chemotherapy, indicating a poor prognosis.
• Trametinib, a MAPK/Erk kinase inhibitor, was administered for 7 months.

Implications:

• Early investigation of patients with large or multiple congenital nevi is recommended.
• MR imaging is the preferred diagnostic tool for NCM.
• A multidisciplinary approach is essential for optimal management of NCM patients, given the complexity and poor prognosis of neurological manifestations.