Pinkus and Mehregan

 
"Criteria for malignancy of a melanotic tumor are several, and some are more significant than others. Presence of mitoses is of primary importance, although some mitotic figures may be found in benign juvenile melanomas and an occasional one even in benign nevi. Absence of mitosis does not rule out malignancy. The next important feature is inflammatory reaction composed of lymphocytes and possibly plasma cells. It is practically always present, but may be absent in rapidly growing tumors and, on the other hand, may also be found in benign juvenile melanoma, nevus incipiens, and Sutton's halo nevus. This reactive infiltrate must not be confused with the acute or granulomatous infiltrate that may be caused in a benign intradermal nevus by infection of a hair root or breakdown of a follicular cyst. Cell size has considerable significance. Cells of malignant melanoma usually are much larger than even the large type A cells of benign nevi, a feature also true for benign juvenile melanoma. One should not be confused by large multinucleated nevus giant cells occurring in benign lesions. Distribution and amount of pigment usually is more variable in malignant melanoma, some nests containing much, others little or none. Particularly characteristic is dustlike pigmentation of large junctional nests. One should not be deceived by the presence of pigmented macrophages, which occur in benign as well as malignant lesions." Pinkus H, Mehregan A. A guide to dermatohistopathology. 2nd Edition. New York: Appleton-Century-Crofts, 1976:471.
 

Brief Critique

 
Pinkus and Mehregan did not add anything to what they wrote about criteria that enable differentiation histopathologically of nevi from melanoma in the first edition of their book. As in the first edition, they admit rightly that none of their criteria, and all of them together, do not permit a distinction to be made between Spitz's nevus and melanoma.