Benign Melanocytic Tumor in Infancy: Discussion on a Rare Case and Review of the Literature

Abstract

Meningeal melanocytoma is an infrequent neoplasm of the central nervous system (CNS), especially in childhood and infancy. It was first described as an entity different from pigmented meningiomas and schwannomas in 1972, and few cases have been published so far. In this article, a 5-month-old male patient with meningeal melanocytoma is presented. This midline lesion was localized in the posterior fossa and manifested by hydrocephalus. The entire dural origin and extradural growing pattern in addition to the destruction of the adjacent occipital bone were the unexpected presentations since these tumors usually tend to locate on leptomeninges and to extend into the adjacent neural compartment rather than the outside. On the other hand, this case is the only one which had identical lesions in both surrenal glands and the left renal capsule, the structures containing neural-crest-derived cells outside the CNS. The prognostic criteria, differential diagnosis and its embryological aspects are discussed with an extensive review of the related existing literature.

Melanotic Neuroectodermal Tumor of Infancy Discovered after Head Trauma

“…At this site, MNTI must be differentiated from melanotic tumors of the leptomeninges and dura [9, 10]. While melanocytic neoplasms rarely (if ever) occur in infants, some histological features may overlap with MNTIs.…”

“…The cells are relatively uniform without mitotic activity and devoid of the nuclear hyperchromasia of the neuroblastic ‘small blue cell’ component seen in MNTIs. Primary leptomeningeal melanomas also occur in adults (age range 15–71 years) in the spinal cord, posterior fossa and less commonly basal leptomeninges [9, 10]. Primary melanomas usually exhibit cytological anaplasia, prominent nucleoli and brisk mitotic activity (averaging approximately 6 mitoses/10 HPF) that exceeds that which is typically encountered in even rare aggressive MNTIs which, on rare occasions, exhibit mitotic activity in the neuroblastic ‘small cell’ component [4].…”

“…Nonetheless, this difference may be difficult to assess in a limited sample involving dura or fibrotic leptomeninges. Metastatic melanoma occurs primarily in adults and exhibits striking nuclear atypia with prominent nucleoli, extensive necrosis and brain invasion [9, 10]. Both tumors, like MNTIs, exhibit S-100 and HMB-45 immunoreactivity, but rarely synaptophysin immunostaining, which is prominent in the neuroblastic ‘small cell’ component of MNTIs.…”

“…Both tumors, like MNTIs, exhibit S-100 and HMB-45 immunoreactivity, but rarely synaptophysin immunostaining, which is prominent in the neuroblastic ‘small cell’ component of MNTIs. Extremely rare melanotic meningiomas occur almost exclusively in adults and usually exhibit whorls and epithelial membrane antigen immunoreactivity not seen in MNTIs or melanocytic neoplasms [10]. …”

Primary melanocytic neoplasms of the central nervous system

“…The age at diagnosis ranges from 9 to 73 years, with a peak incidence in the fifth decade and a slight female preponderance. 25,28,38 Associated melanotic lesions in the kidneys and adrenal glands and aggressive leptomeningeal spread throughout the neuraxis have been reported [38][39][40] (Table 2).…”