Adult-onset neurocutaneous melanosis with Dandy–Walker malformation

Neurocutaneous melanosis (NCM) is characterized by diffuse or focal proliferation of melanin-producing cells over the skin or leptomeninges. Even without malignant transformation, the prognosis is poor after symptomatic progression of NCM, resulting from either mass effect in central nervous system or hydrocephalus. We reported a 26-year-old female patient with rapid deterioration after the onset of NCM. Despite no solid tumor formation, elevated cerebrospinal fluid protein content, which complicated shunting procedure, associated with hydrocephalus played the key role in clinical deterioration. Adult onset of NCM with Dandy–Walker malformation was never reported in our literature review. Diagnosis and treatment for such disease entity are discussed.