Other types of eruption are less common, and are met with from the third month onwards. A _pustular_ eruption, not unlike that of acne, is sometimes a prominent feature, but is not characteristic of syphilis unless it affects the scalp and forehead and is associated with the remains of the papular eruption. The term _ecthyma_ is applied when the pustules are of large size, and, after breaking on the surface, give rise to superficial ulcers; the discharge from the ulcer often dries up and forms a scab or crust which is continually added to from below as the ulcer extends in area and depth. The term _rupia_ is applied when the crusts are prominent, dark in colour, and conical in shape, roughly resembling the shell of a limpet. If the crust is detached, a sharply defined ulcer is exposed, and when this heals it leaves a scar which is usually circular, thin, white, shining like satin, and the surrounding skin is darkly pigmented; in the case of deep ulcers, the scar is depressed and adherent (Fig. 39). [Illustration: FIG. 39.--Syphilitic Rupia, showing the limpet-shaped crusts or scabs.] In the later stages there may occur a form of creeping or _spreading ulceration of the skin_ of the face, groin, or scrotum, healing at one edge and spreading at another like tuberculous lupus, but distinguished from this by its more rapid progress and by the pigmentation of the scar. _Condylomata_ are more characteristic of syphilis than any other type of skin lesion. They are papules occurring on those parts of the body where the skin is habitually moist, and especially where two skin surfaces are in contact. They are chiefly met with on the external genitals, especially in women, around the anus, beneath large pendulous mammæ, between the toes, and at the angles of the mouth, and in these situations their development is greatly favoured by neglect of cleanliness. They present the appearance of well-defined circular or ovoid areas in which the skin is thickened and raised above the surface; they are covered with a white sodden epidermis, and furnish a scanty but very infective discharge. Under the influence of irritation and want of rest, as at the anus or at the angle of the mouth, they are apt to become fissured and superficially ulcerated, and the discharge then becomes abundant and may crust on the surface, forming yellow scabs. At the angle of the mouth the condylomatous patches may spread to the cheek, and when they ulcerate may leave fissure-like scars radiating from the mouth--an appearance best seen in inherited syphilis (Fig. 44).