Congenital Melanocytic Nevi Syndrome With Leptomeningeal Melanoma

Abstract

The incidence of congenital melanocytic nevi (CMNs) is 1% to 6% for small- to intermediate-size nevi to 1 in 500,000 for giant size nevi. Large and satellite CMNs are known to be associated with neurocutaneous melanosis and central nervous system malformations such as Dandy-Walker malformation, defects of the vertebra-skull, and intraspinal lipomas. We hereby present a case of CMN syndrome in an 18-year-old girl with leptomeningeal melanoma, evaluated with MRI, adequately staged, and screened with FDG PET.

Transformed Giant Congenital Melanocytic Nevus on 18F-FDG PET/CT

“…The risk factors for giant congenital melanocytic nevus to have malignant transformation include being present at birth, larger nevi (>50 cm), axial locations, multiple satellite lesions, dark patches, deep dermal neurogenic elements, or a blue nevus component. [6][7][8][9] Subsequent pathology from the biopsy of the lesion in the right lower lobe of the lung confirmed malignant melanoma. It is known that when giant congenital melanocytic nevus was discovered at, or shortly, after birth, 6%-50% will develop to melanoma by the age of 2 years and 80% of those by the age of 7 years.…”

“…Further medical history inquiry uncovered that giant congenital melanocytic nevus was diagnosed at the patient’s birth. The risk factors for giant congenital melanocytic nevus to have malignant transformation include being present at birth, larger nevi (>50 cm), axial locations, multiple satellite lesions, dark patches, deep dermal neurogenic elements, or a blue nevus component 6–9 . Subsequent pathology from the biopsy of the lesion in the right lower lobe of the lung confirmed malignant melanoma.…”

18F-FDG PET/CT Findings of Leptomeningeal Metastasis in Nasopharyngeal Carcinoma

“…Also noted are FDG-avid left cervical and supraclavicular nodal metastasis on MIP image. Traditionally, CSF cytology and MRI have been used in the diagnosis of leptomeningeal metastasis 9–11 . PET/CT has shown utility in this case by accentuating the extent of disease.…”