#Epithelioma# occurs in a variety of forms.  When originating in a small ulcer or wart-for example on the face in old people—­it presents the features of a chronic indurated ulcer.  A more exuberant and rapidly growing form of epithelial cancer, described by Hutchinson as the crateriform ulcer, commences on the face as a small red pimple which rapidly develops into an elevated mass shaped like a bee-hive, and breaks down in the centre.  Epithelioma may develop anywhere on the body in relation to long-standing ulcers, especially that resulting from a burn or from lupus; this form usually presents an exuberant outgrowth of epidermis not unlike a cauliflower.  An interesting example of epithelioma has been described by Neve of Kashmir.  The natives in that province are in the habit of carrying a fire-basket suspended from the waist, which often burns the skin and causes a chronic ulcer, and many of these ulcers become the seat of epithelioma, due, in Neve’s opinion, to the actual contact of the sooty pan with the skin.

The term trade epithelioma has been applied to that form met with in those who follow certain occupations, such as paraffin workers and chimney-sweeps.  The most recent member of this group is the X-ray carcinoma, which is met with in those who are constantly exposed to the irritation of the X-rays; there is first a chronic dermatitis with warty overgrowth of the surface epithelium, pigmentation, and the formation of fissures and warts.  The trade epithelioma varies a good deal in malignancy, but it tends to cause death in the same manner as other epitheliomas.

Epithelial cancer has also been observed in those who have taken arsenic over long periods for medicinal purposes.

[Illustration:  FIG. 102.—­Rodent Cancer of Inner Canthus.]

#Rodent Cancer# (Rodent Ulcer).—­This is a cancer originating in the sweat glands or sebaceous follicles, or in the foetal residues of cutaneous glands.  The cells are small and closely packed together in alveoli or in reticulated columns; cell nests are rare.  It is remarkably constant in its seat of origin, being nearly always located on the lateral aspect of the nose or in the vicinity of the lower eyelid (Fig. 102).  It is rare on the trunk or limbs.  It commences as a small flattened nodule in the skin, the epidermis over it being stretched and shining.  The centre becomes depressed, while the margins extend in the form of an elevated ridge.  Sooner or later the epidermis gives way in the centre, exposing a smooth raw surface devoid of granulations.

[Illustration:  FIG. 103.—­Rodent Cancer of fifteen years’ duration, which has destroyed the contents of the Orbit.

(Sir Montagu Cotterill’s case)]