In 1948, Carleton and Biggs shared with colleagues their experience with a 14-year-old girl who had numerous bluish bruise-like spots, some superficial and some deep-seated, referred to by them as "diffuse mesodermal pigmentation." [5] Pigmented spots on the sclerae had been present since birth. The histopathologic findings were chronicled in these lines:

"In the dermis there is a widespread infiltration of dendritic or bipolar cells containing fine brown pigment granules . . . These cells are congregated around blood vessels and sweat ducts, but in addition they are scattered through the dermis in among the collagen fibers and in neither biopsy is there any suggestion of circumscription such as is seen in a blue nevus." [6]

Although the authors stressed the adnexocentricity and angiocentricity of the cells pigmented, they attached no importance to that phenomenon. They also seemed to think that "circumscription" is a criterion necessary for diagnosis of blue nevus.

In their discussion, the authors compared the changes in the lesion in their patient with those of equine melanotic disease, the differences noted by them being as follows:

"This picture [in horses] is obviously much more intensive than in the case we are recording. One cannot assert that there is no involvement of the deeper mesodermic tissue in our case, but the absence of melanin in the urine suggest that this involvement, if present, is not widespread." [6]

On the basis of these differences, the coworkers concluded that: " . . . this case represents a diffuse abnormality in mesodermal pigmentation, not exactly comparable with any hitherto described condition . . ." [6] Not even equine melanotic disease! They went on to say that "This picture [in horses] is obviously much more extensive than in the case we are recording." [6]