Abstract
The author has performed study on the histogenesis of the nevus cells in the nevocellular nevi. In the study, specimens of the intradermal nevi in 124 cases were evaluated histologically and immunohistochemically and the following results were obtained:
1) Findings of hematoxylin eosin staining
It was observed that three types of cells, including type A cells (epidermoid type cells), type B cells lymphoid type cells), type C cells (neuroid type cells) were found to run through an intermediate stage f r (om the upper part to the lower part of the nevocellular structure, although they disclosed different histological structures. In 39 (31.5%) of the 124 cases, Meissner's corpuscle-like cells were confirmed.
2) Findings of immunohistochemical staining
i. Of the type A, type B and type C cells, the S-100 α protein stain was essentially negative. Meissner's corpuscle-like cells were selectively positive by this stain.
ii. Although no particular difference was noted in the staining of S-100 protein between the type A and type B cells, a somewhat greater proportion of positive cells was noted in type C cells. In the Meissner's corpuscle-like cells, a notably higher positive conversion of cells was observed as compared to those of the three other types of cells.
iii. Type A, type B and type C cells compared more or less similarly for the positive ratio of neuronspecific enolase but the ratio was unusually high in the Meissner's corpuscle-like cells.
3) Findings from routine electron microscopic staining
i. Similar to the light microscopic findings, the nevus cells were found to change in shape uninterruptedly from the upper layer to the lower layer of the dermis. Unusually marked changes were noted both in the number and shape of the melanosome and premelanosome in the cytoplasm.
ii. In the Meissner's corpuscle-like cells both melanosomes and premelanosomes were missing but a finding suggestive of a neuroid structure was affirmed.
As noted above, the results of the histological, immunohistological and electron microscopic studies were in support of the general findings suggestive of a gradual shift of the nevus cells from the upper layer to the lower layer in the dermis, which prompted the author to support the so-called “neural crest origin hypothesis”.
