Age related changes in brain MR appearance in the course of neurocutaneous melanosis.

BACKGROUND: Patients with giant congenital melanocytic nevi (GCMN) have increased risk of neurocutaneous melanosis (NCM). Brain MRI is mandatory in GCMN.

OBJECTIVES: To present the age related changes in brain MRI in children with NCM during several-year follow-up.

METHODS: In 7 NCM children following data were analyzed: main nevus localization, surgical treatment phase, histology of excised nevi, time of NCM diagnosis, number of MRI studies, neurological symptoms, changes of melanin deposits in brain during follow-up.

RESULTS: Four children had bathing trunk nevus, two main nevus on back, one on head. Surgical excision is finished in 3 patients, 4 are in the course of multistage surgery. In one melanoma arising in GCMN was diagnosed. Six patients are neurologically healthy, one suffers from seizures. Age of patients at first MRI ranged from 12days to 7 years. All patients underwent more than one MRI. Follow-up period ranges from 2.5 to 8.5 years. Most of T1-hyperintense foci in brains regressed with time. In one case new lesion appeared, in one more lesions were visible on second MRI.

CONCLUSIONS: In all patients with NCM on subsequent MRI image changes were found with respect to original location and size of melanin deposits in CNS. Changes of NCM appearance on MRI with advancing age of patients reflect natural history of this disorder. Theory of gradual disappearance of intracerebral melanin deposits with age seems to be more likely than theory of their worse visualization on MRI with time.