Kopf and Andrade shared with readers the substance of correspondence they had initiated with Allen in regard to "malignant transformation" of benign juvenile melanoma to malignant melanoma. What follows is the gist of that exchange:

The statement by Allen that "I believe it is a disservice to endow the juvenile melanoma with a special cancerous potential" is curious when one considers the fact that it was his wife, Spitz, who, in 1948, had endowed juvenile melanoma with attributes of cancer when she wrote, without equivocation, that "the term 'melanoma' in this paper as in common usage, has been applied only as an abbreviation for malignant melanoma"⁷ and when one remembers that it was Allen, himself, in 1949, who was equivocal about the biologic behavior of juvenile melanoma, averring as he did then that "it is a remarkable fact that prior to puberty these lesions do not metastasize except in the rarest instances."⁸ Spitz never acknowledged that it was she who, in 1948, set forth the proposition that juvenile melanoma was malignant melanoma, and Allen never referred in his many publications about the subject, some of them 40 years after his first article about the matter appeared in 1949, to the "remarkable fact" that Spitz initially conceived of juvenile melanoma as malignant melanoma.

Allen was asked this question by Kopf and Andrade:

"'Would you comment on your statement (Cancer 6:1-46, 1953) to the effect that in 5.9% of 362 malignant melanomas 'there is noted residual evidence of pre-existing juvenile melanoma'? Does this imply that juvenile melanomas have given rise to malignant lesions?' His reply was: 'The incidence you mention of antedating juvenile melanomas is based, as we indicated, on the finding of a few landmarks suggestive of juvenile melanoma at the periphery of malignant melanomas. As I say, the juvenile melanomas are often difficult enough to diagnose when the entire, unaltered lesion is available for review, so that perhaps the figure of 5.9% is high from the point of view you mention. Again, the basic point, which this particular kind of partial evaluation should not be used to negate out of text, is that the juvenile melanoma is no more grave a lesion than the junctional nevus or compound nevus.'"

Once again Allen dodged; his answer should have been that the statement by him in 1953 was wrong because that which was said by him to be residual juvenile melanoma really was malignant melanoma.¹² Moreover, juvenile melanoma cannot be contrasted neatly with a "junctional nevus or compound nevus" because it may be junctional, compound, or intradermal. Juvenile melanoma, being a specific type of nevus, can be contrasted only with other specific types of nevi, such as those of Unna, Miescher, and Clark.

Based on this dialogue with Allen and on their own review of the literature, Kopf and Andrade came to this position in regard to the character biologically of juvenile melanoma:

On "critical review" it can be asserted, trenchantly, that any benign juvenile melanoma alleged to have metastasized actually was a malignant melanoma misdiagnosed histopathologically as a nevus.