P2.241: More than a Birthmark: A Newborn’s Diagnosis of Neurocutaneous Melanosis

Introduction: The giant congenital melanocytic nevus (GCMN) is a hyperpigmented lesion present at birth, associated with an increased risk of malignant melanoma and neurologic abnormalities. We present a case of a newborn whose presenting dermatological findings resulted in a rare diagnosis of neurocutaneous melanosis.

Case Description: The patient is a female infant born at 39 weeks gestation with no significant prenatal history, with findings of diffuse hyperpigmented skin lesions covering approximately 80% of her face and body at the time of delivery (Fig 1). Nevi of varying thickness, some with hair, covered the back, trunk, face, and extremities in a bathing suit distribution. Due to concern for underlying pathology, the patient was admitted to the NICU, with consultations to neurology and dermatology. Initial head sonogram and ultrasound of the spinal canal on day of life (DOL) 1 were normal. A gadolinium-enhanced magnetic resonance imaging scan of the brain and spine revealed multiple paraspinal masses and one intraspinal mass from T9 to T11 causing leftward spinal cord displacement. Genetic testing was deferred, as this was thought to have resulted from a somatic mutation. Patient underwent a fontanelle tap for CSF collection on DOL 12. Pathology showed no evidence of a neoplastic process. On DOL 15, head circumference was noted to have increased from 35 cm to 37 cm over the course of 2 days, with spinal and head ultrasound showing new spinal mass, indicative of disease progression. A ventriculoperitoneal shunt was placed on DOL 22, to relieve hydrocephalus. A family meeting was held, and options including pursuit of biopsy versus hospice care were discussed. After comprehensive tumor board discussion, an interdisciplinary decision was made to proceed with scheduled multilevel thoracic laminectomy for tumor resection of compressive spinal lesion.

Discussion: The incidence of GCMN in newborns, reported between 0.2% and 2.1%, is quite low, yet the presence of this lesion increases the risk of neurocutaneous melanosis and malignant melanoma. GCMN are the result of unregulated proliferation of melanoblasts, which migrate from the neural crest to the skin, mesentery, eyes, ears, and leptomeninges. They are thought to arise from post-zygotic mutations such as NRAS (Q61) and BRAF (V600). Satellite lesions, and involvement of the midline of the trunk have been associated with an increased risk of CNS involvement. The standard in diagnosis includes magnetic resonance imaging of the brain and spinal cord. Symptoms such as increased intracranial pressure, hydrocephalus, and seizure can present indicate a poorer prognosis. Currently, the management of children with GCMN is controversial, as there is no standard treatment.

Conclusion: Early recognition of association of the GCMN with development of melanoma or neurocutaneous melanosis is of importance in management of potential complications of CNS involvement.