On the natural history and comparative pathology of the blue naevus.

In man the epidermis is the final destination for most of the melanocytes which are of neural crest origin, and they migrate to a variety of sites. Dermal melanocytic distribution, conspicuous in some lower animals, has a very restricted normal distribution in man, and of the variety of anomalies which exist the blue naevus is the most frequently encountered. It is comparable to the common melanocytoma of dog and hamster. More widespread dermal melanocytoses are rare, and a unique case in which death from melanoma supervened, recently recorded by the author, is an example of a syndrome the only parallel to which appears to be equine melanotic disease, a disorder of aging, greying horses. It is argued on comparative grounds that the newly described syndrome and equine melanotic disease are examples of a neurochristic disorder involving the cephalad segments and dermal melanocytes.