The nodular cancers arise from a pre-existing lesion. A pearly nodule first forms, which slowly grows until in from six months*' to one year's time the growth has attained a diameter of 1 cm. and an elevation above the skin of about the same. The lesion is roughly semiglobular in shape, may be slightly um-bilieated, and is very hard and firm to the touch (Figs. 24, 25). """\e color is pinkish-white or grey, and there are dilated vessels ning into the tumor. Later, ulceration may take place in the ter (Figs. 26, 27), and the neoplasm run any of the courses already described under the heading of the flat rodent ulcer. This type is in reality simply a modification of the rolled-edge rodent ulcer type.
Histologically, the lesion at first shows the characteristics of the Carcinoma basocellulare solidum, but later changes to some of other types, as has already been described, the only difference being that the changes are comparatively slow, and that cysts rarely form.
Fig. 26.-This large basal-celled cancer of the hand sprang from a seborrheic keratosis. Notice a healed lesion upon the middle linger. This is an unusual tumor, for neoplasms of the hands are usually of the splno-celled type. (Sutton's collection).
Gummata and benign epithelial, fibroid, or cystic tumors must not be mistaken for this type of growth.