The usefulness of single and combined clinical characteristics for the diagnosis of dysplastic naevi.

A total of 761 melanocytic lesions were studied to elucidate the usefulness of clinical features for the diagnosis of dysplastic naevi. Characteristics associated with high (irregular border, irregular pigmentation), intermediate (black coloured areas, largest diameter greater than 0.5 cm, change of size, change of colour) and low diagnostic efficiency could be defined. Combinations of criteria had high sensitivities: at least one of the following four criteria was positive in 96% of the dysplastic naevi and in all melanomas with less pronounced clinical characteristics: irregular border, irregular pigmentation, greatest diameter greater than 0.5 cm, black coloured areas. A lesion is therefore unlikely to be a dysplastic naevus or a melanoma if all these criteria are absent. When change of size and change of colour were analysed in addition to the features mentioned above a sensitivity of 0.96 was found for at least two of these six criteria. At least three of these six criteria were observed in all melanomas with less pronounced clinical characteristics. However, a rather low specificity (0.19 for at least one of four positive criteria, 0.20 for at least two of six positive criteria) indicated that dysplastic and non-dysplastic naevi cannot be clinically differentiated with acceptable certainty. With less stringent histological criteria approximately twice as high specificities were found. Specificities were about twice as high in a subgroup of patients with at least one proven dysplastic naevus besides the lesion under diagnostic consideration. This facilitates the identification of individuals at risk of developing a melanoma.

Architectural features in melanocytic lesions with cellular atypia.

According to the quantity of single atypical melanocytes at the dermoepidermal junction 334 nevi were assigned to 3 groups: (1) with pronounced nuclear and cellular atypia (n = 73); (2) with moderate atypia (n = 127), and (3) without atypical melanocytes (n = 134). Three architectural features were almost exclusively observed in groups 1 and 2 with cellular and nuclear atypia: atypical localization of melanocytes in the epidermis, irregular distribution of melanocytes in the junctional zone and atypical nests of melanocytes. A combination of 2 or 3 of these features was seen in 76% of the nevi with pronounced cellular and nuclear atypia, in 28% of those with moderate atypia and in none of those without atypical melanocytes. Regarding 4 other criteria only minor but still statistically significant differences were found between the 3 groups of nevi. We conclude that these 4 other criteria, i.e. inflammatory infiltrate, lamellar and/or concentric fibroplasia, persisting lentiginous hyperplasia and dust-like pigment in melanocytes and nevus cells are not helpful for the diagnosis of a dysplastic nevus because of their low specificity. Minimal requirements for the diagnosis of a dysplastic nevus are suggested.

Ultrastructural morphometry of cultivated smooth muscle cells from normotensive and hypertensive rats.

Cultivated aortic smooth muscle cells (SMC) derived from normotensive and hypertensive rats were analyzed by transmission electron microscopy and ultrastructural morphometry. SMC cultures obtained from hypertensive rats showed an increase in cell size and a higher percentage of large, often polynuclear cells. The stereological data of mitochondria, rough endoplasmic reticulum (RER) and secondary lysosomes were determined by measuring area according to the "Delesse principle". The organelle contents of small and large cells of each group were only slightly different. Significant changes were found between SMC from normotensive and hypertensive rats: The volume density Vv of mitochondria per unit cytoplasm volume was increased up to 48% in small and 50% in large SMC from hypertensive rats compared to those of control animals. The numerical density Nv of secondary lysosomes per unit cytoplasm volume was increased up to 68% in small and 267% in large SMC from hypertensive rats. The content of rough endoplasmic reticulum varied tremendously between the individual cells. All these stereological data represent relative parameters of cell organelles relative to the unit cytoplasm volume. Therefore the differences between the absolute values would be even higher since SMC from hypertensive rats are shown to have a higher mean cell size and volume. We conclude that the effect of experimental hypertension, resulting in an activation of SMC, persists even when the cells are transferred to in vitro conditions.