Correlating architectural disorder and cytologic atypia in Clark (dysplastic) melanocytic nevi.

Histological architecture is very important in the pathological diagnosis of Clark (also known as atypical or dysplastic) melanocytic nevi. However, few studies have attempted to quantify architectural features or to correlate them directly with cytology. In 166 consecutive Clark nevi, the presence or absence of the following features in the intraepidermal or junctional component was recorded: (1) Architecture: circumscription, symmetry, cohesiveness of nests, suprabasal melanocytes, confluence, and single-cell proliferation; (2) Cytology of melanocytes: round/euchromatic nuclei, nuclear enlargement, cell enlargement, and prominent nucleoli. Each criterion was given a value of 0 or 1, and a summation score was obtained for both architecture and cytology in each case. The chi-square test was used to determine the significance of relationships among these parameters. The degrees of architectural disorder and of cytologic atypia were positively correlated (P = .026). Scores for both parameters were distributed over a wide range of values and were concentrated toward the low-middle portion of the spectrum. Several particular architectural and cytologic variables showed significant interdependence. Clark nevi exhibit a broad spectrum of architectural disorder and cytologic atypia, which, according to our data, generally are closely related features. Because some cases displayed a relatively high score for one parameter but a low score for the other, quantification of both parameters permits a more complete histopathologic evaluation of these lesions and may provide additional information for their clinical management.