Historical Perspective: Crotty et al., 1992

 
In an article that appeared in 1992 about "Malignant melanoma in childhood: A clinicopathologic study of 13 cases and comparison with Spitz nevi," K. A. Crotty and coworkers48 contrasted 13 de novo melanomas in children 13 years of age or younger with those in a control group of 17 nevi in children of the same age, all of whom lived in New South Wales, Australia. Fifteen were deemed by them to be Spitz's nevi, one a "combined blue and nevocellular nevus", and one a "compound nevus." The authors performed a computerized analysis on "320 clinical and histological variables" and, predicated on the findings, sought to establish clinical features and histopathologic findings that would allow a distinction to be made between Spitz's nevus and melanoma. The clinical features that were helpful to them in coming to a diagnosis of melanoma were these:
 
"The [clinical] features proportionally more common in malignant melanomas were bleeding, ulceration, itching, black color, and variegated or mottled color."
 
With respect to the histopathologic findings that favored melanoma rather than Spitz's nevus they said this:
 
"Those features proportionally in favor of the melanomas . . . include mitosis within 0.25 mm of the dermal margin of the melanoma, a dermal mitotic rate exceeding 2 mm,2 ulceration, surface exudate, large pigment granules, and clear-cell differentiation. Similarly, those features proportionally favoring Spitz's nevi . . . include absence of mitosis, predominance of spindle cells, and diffuse maturation in the dermis."
 
The experience with melanomas in children led Crotty and collaborators to summarize their findings in this way:
 
"Of the 13 children with malignant melanoma in this series, 6 died with their disease 1 to 13 years after diagnosis. The thickness of the 4 fatal primary melanomas available for study ranged from 1.6 mm to 5.5 mm (median 2.9 mm) . . . Absence of mitosis, predominance of spindle cells, and diffuse maturation favored Spitz's nevus. The median thickness of the Spitz's nevi was 0.7 mm."
 
Unfortunately, none of the criteria employed by Crotty et al. for differentiation histopathologically of Spitz's nevus from melanoma pertain to architectural pattern, in particular to silhouette, which, despite the negative comments about it by Allen in 199146 (no reason for that opinion was given by him), we consider to be of great importance in deciding whether a neoplasm is benign or malignant, the reason being, as stated previously, that the silhouette of a neoplasm is the representation morphologically of its behavior biologically.