A clinicopathologic and immunohistochemical analysis of melanotic neuroectodermal tumor of infancy.
OBJECTIVE
The purpose of this study was to review the features of 8 cases of melanotic neuroectodermal tumor of infancy (MNTI) of the jaws with respect to the expression of NB84, CD99, PGP 9.5, specific cytokeratins, and Ki-67, markers not previously reported in this entity.


METHODS
A clinicopathologic and immunohistochemical analysis of MNTIs in 8 children was undertaken.


RESULTS
Patients were aged 2(1/2) months to 14 months. Seven were males. Seven lesions affected the maxilla. Microscopically, collections of larger, melanocyte-like cells were admixed with smaller, neuroblast-like cells. All MNTIs contained melanin; although most showed cellular atypia, mitoses were infrequent (<2 per 10 high-power fields). However, in one lesion in which the melanocyte-like cells appeared less differentiated, 7 mitoses per 10 high-power fields were counted. The larger cells expressed cytokeratins 7 (4/8), 8 (8/8), 18 (6/8), and 19 (3/8); PGP 9.5; neuron-specific enolase (6/8); S100; HMB45; and chromogranin A (2/8). The small cells expressed CD56 (7/8), neuron-specific enolase (7/8), synaptophysin (3/8), PGP 9.5 (3/8), and chromogranin A (2/8). No MNTIs expressed NB84. The most mitotically active tumor was the only one to show membrane expression of CD99 (by both cell populations), have a detectable Ki-67-positive fraction (25% in both the large- and small-cell components), behave aggressively, and require bilateral maxillectomy. All other MNTIs responded to local excision, and none metastasized.


CONCLUSIONS
Most MNTIs are benign and respond to conservative excision. Histology is an unreliable means of predicting clinical behavior, but this study has identified some morphologic and phenotypic features that may indicate a more aggressive lesion.
Barrett
A W
AW
Oral and Maxillofacial Pathology Unit, Eastman Denatal Institute for Oral Healthcare Sciences, University College, London, United Kingdom. A.Barrett@eastman.ucl.ac.uk
Morgan
M
M
Ramsay
A D
AD
Farthing
P M
PM
Newman
L
L
Speight
P M
PM
D000071443:12E7 Antigen; D015703:Antigens, CD / Q000032:analysis; D014408:Biomarkers, Tumor / Q000032:analysis; D015815:Cell Adhesion Molecules / Q000032:analysis; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D007223:Infant; D007573:Jaw Neoplasms / Q000737:chemistry / Q000473:pathology*; D007633:Keratins / Q000032:analysis; D019394:Ki-67 Antigen / Q000032:analysis; D008297:Male; D008938:Mitosis; D017600:Neuroectodermal Tumor, Melanotic / Q000737:chemistry / Q000473:pathology*; D010751:Phosphopyruvate Hydratase / Q000032:analysis; D013869:Thiolester Hydrolases / Q000032:analysis; D043222:Ubiquitin Thiolesterase
D000071443:12E7 Antigen; D015703:Antigens, CD; D014408:Biomarkers, Tumor; C061828:CD99 protein, human; D015815:Cell Adhesion Molecules; D019394:Ki-67 Antigen; D007633:Keratins; D013869:Thiolester Hydrolases; D043222:Ubiquitin Thiolesterase; D010751:Phosphopyruvate Hydratase