Neurotized nevi of the oral mucosa: an immunohistochemical and ultrastructural analysis of nevic corpuscles.
BACKGROUND
Nevic corpuscle (NC), a stacked lamellar structure reminiscent of Meissner corpuscle, is frequently observed in dermal melanocytic nevi. Although the heading 'neurotized' is classically used for these nevi, the exact neural nature of NC has been a topic of considerable debate. Neurotized nevi have received little attention in the dental literature, and there was no information on NC in oral melanocytic nevi.


METHODS
Six cases of oral intramucosal nevi with a significant number of NC (two completely and four partially neurotized nevi) were examined immunohistochemically and ultrastructurally.


RESULTS
NC was composed of closely piled laminar cells devoid of visible melanin. NC and associated spindle nevus cells were immunopositive for S-100 protein but negative for HMB-45, myelin basic protein and epithelial membrane antigen. Within NC, no reactivity for neurofilament protein, protein gene product 9.5 or peripherin was evident. Numerous CD34-positive dendritic cells were located between nevus cells and often encircled NC. Ultrastructurally, NC consisted of concentrically layered elongated cells with a slender lamellated cytoplasm rich in thin filaments and pinocytotic vesicles. Their cytoplasmic processes were focally covered by external basal lamina and continuous to spindle nevus cells. Occasional NC cells contained a few melanosomes. There was no interposed axon in NC.


CONCLUSIONS
Despite the close resemblance to Meissner corpuscle, NC showed no axonal supply. NC cells lacked terminal Schwannian differentiation and appeared to be modified melanocytes with some perineurial ultrastructural characteristics. The presence of CD34-positive cells, presumably corresponding to endoneurial fibroblasts, further supports an organizational relationship of NC and peripheral nerve sheath elements.
Ide
F
F
Division of Pathology, Department of Diagnostic and Therapeutic Sciences, Meikai University School of Dentistry, Saitama, Japan. idef@dent.meikai.ac.jp
Mishima
K
K
Yamada
H
H
Saito
I
I
Tanaka
A
A
Kusama
K
K
D000328:Adult; D018952:Antigens, CD34 / Q000032:analysis; D000951:Antigens, Neoplasm / Q000032:analysis; D003593:Cytoplasm / Q000648:ultrastructure; D003713:Dendritic Cells / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007381:Intermediate Filament Proteins / Q000032:analysis; D008465:Mechanoreceptors / Q000473:pathology* / Q000648:ultrastructure; D008543:Melanins / Q000032:analysis; D008544:Melanocytes / Q000473:pathology; D058950:Melanoma-Specific Antigens; D020460:Melanosomes / Q000648:ultrastructure; D008562:Membrane Glycoproteins / Q000032:analysis; D008875:Middle Aged; D009061:Mouth Mucosa / Q000473:pathology* / Q000648:ultrastructure; D009062:Mouth Neoplasms / Q000473:pathology* / Q000648:ultrastructure; D018396:Mucin-1 / Q000032:analysis; D004676:Myelin Basic Protein / Q000032:analysis; D009363:Neoplasm Proteins / Q000032:analysis; D009419:Nerve Tissue Proteins / Q000032:analysis; D016900:Neurofilament Proteins / Q000032:analysis; D009506:Nevus / Q000473:pathology* / Q000648:ultrastructure; D064531:Peripherins; D009418:S100 Proteins / Q000032:analysis; D043222:Ubiquitin Thiolesterase / Q000032:analysis; D014617:Vacuoles / Q000648:ultrastructure
D018952:Antigens, CD34; D000951:Antigens, Neoplasm; D007381:Intermediate Filament Proteins; D008543:Melanins; D058950:Melanoma-Specific Antigens; D008562:Membrane Glycoproteins; D018396:Mucin-1; D004676:Myelin Basic Protein; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D016900:Neurofilament Proteins; C578994:PRPH protein, human; D064531:Peripherins; D009418:S100 Proteins; C482860:UCHL1 protein, human; D043222:Ubiquitin Thiolesterase