The various manifestations in the skin are the results of the action of the syphilitic vims. The lesions, like those elsewhere, are either simply inflammatory, or they have the characters of the gumma, forming in the latter case more or less definite tumours composed of granulation tissue. Even the purely inflammatory lesions have a tendency, when they have persisted long, to present considerable new-formation of granulation tissue. The syphilitic lesions of the skin may be divided into the primary, secondary, and tertiary.

(A) The Hard Chancre

The Hard Chancre has been already described. It is characterized by a hard indurated base due to an infiltration or replacement of the soft and pliant cutis vera by granulation tissue.

(B) Skin Eruptions Of Secondary Stage. Syphilides

Skin affections are the principal manifestations of this stage, and as the virus is in the blood the manifestations occur as a rule over the skin as a whole, although circumstances may determine a certain local selection. The eruptions are for the most part symmetrical, and they present a peculiar tendency to occur in round patches of a definite size. These patches, by healing in the centres and extending at the periphery, frequently assume a circular or serpiginous outline.

The syphilitic eruptions of the secondary stage are somewhat similar in character to the simple inflammatory eruptions, and they are commonly designated by similar names. There is, however, more tendency in the syphilides to the development of granulation tissue in the skin, and hence the papular forms of eruption are more frequent. Whilst there is a certain order of frequency which usually obtains, yet there is no absolute fixedness in the rotation of the syphilides. In the earliest periods there is usually a generalized hyperemia of the skin (Syphilitic erythema or roseola). A more local development of elevated papules, generally in groups, constituting the syphilitic lichen, is the usual form to follow. In these papules, the corium, especially its superficial layers, and to a certain extent the epidermis, are infiltrated with round cells; generally there is desquamation of epidermis, and this is sometimes very prominent. Occurring in the palms of the hands and soles of the feet this desquamation is so characteristic as to give rise to the designation syphilitic psoriasis, the resemblance to psoriasis being increased by the fact that the papules after a time coalesce and there is thus produced a generally raised surface.

The Condyloma (Plaque muqueuse, mucous tubercle) is a further and usually a later development of the papule. It occurs generally in situations where two surfaces of the skin are in contact and are thus kept moist, as in the neighbourhood of the genital organs, in the axilla, beneath the mamma, etc. We have here a very marked and extensive infiltration of the papillary layer of the skin with round cells, so that an elevated surface is formed. Sometimes there is a special elongation of the papillae, so that a warty surface is produced, giving rise to the Pointed condyloma. Sometimes the condyloma breaks down on the surface and an ulcer forms.

The syphilitic papules sometimes develop into pustules or vesicles. The pustule forms by the epidermis being raised from the surface. while a fluid inflammatory exudation occurs between it and the corium, which latter remains infiltrated with round cells. The pustule of vesicle and its infiltrated base may enlarge so as to produce a broad bleb on a red raised base (Syphilitic pemphigus). The blebs often dry-in and form raised crusts (Rupia). In these cases the pustules are as if on the surface of condylomata. This is still more the case in Pemphigus neonatorum, which is one of the manifestations of hereditary syphilis. Here the corium is affected somewhat as in the condyloma, but the infiltration has more the characters of granulation tissue. In the condyloma the structure of the skin remains to a great extent, but it is infiltrated with round cells, which are mostly leucocytes. In pemphigus neonatorum, however, the tissue is replaced by a vascular tissue in which are many large cells, the condition approaching to that of the minima. On the surface of this the epidermis is raised, forming a vesicle or pustule.

(C) The Gumma

This is, as we have seen, a special tertiary manifestation. It begins as a hard swelling in the cutis. It increases in size and raises the surface, sometimes forming a tumour of considerable dimensions. The gumma, which may be multiple, is prone to ulceration. The Gummatous ulcer somewhat resembles the hard chancre, being an indolent ulcer with a hard base. There may be extensive destruction of the skin by the gradual extension of the ulcer.