Pustular Syphilid (Syphilis Pustulosa)

Pustular syphilid is much rarer than macular or papular syphilid. It develops in weakened patients and in individuals abusing alcohol. It is predominantly localized on the scalp, in the small of the back, and on the legs. Pustular syphilids are often combined with papular syphilids. Several variants of pustular syphilids are distinguished which must be differentiated with pustular lesions, mainly those caused by staphylococcal flora.

In impetigo syphilitica a pustule forms in the centre of the papule and rapidly dries to a crust. The absence of a tendency of the lesion to peripheral growth and coalescence, the absence of subjective disturbances, the information gained from the medical history, the results of serological blood tests, and other clinical manifestations of the secondary period of syphilis enable the physician to make a differential diagnosis with impetigo vulgaris.

Acne syphilitica resembles acne vulgaris clinically. In making the diagnosis one should take into account the absence of seborrhoeic phenomena (comedones in particular), localization of the eruption also on areas not typical of seborrhoea, and other symptoms of the secondary period of syphilis.

Varicella syphilitica occurs in weakened patients as a rule and is characterized by the formation of a spherical pustule the size of a small pea. The centre of the pustule dries very rapidly to a crust and is retracted (in this the morphological lesion resembles the smallpox pustule), and a swelling of brownish-red infiltration forms around the lesion. There are usually a few lesions (10-20) and the process lasts a considerable length of time (5-7 weeks) as a rule and leaves no scars. Smallpox and chickenpox, with which a differential diagnosis has to be made, are characterized by an acute course, the severe general condition of the patient, the absence of an infiltrate around the pustules, by an abundance of lesions and the absence of other symptoms of secondary syphilis, a negative blood test for Wassermann's reaction among others.

Ecthyma syphilitica is a rare but severe manifestation of pustular syphilid. There are usually a few lesions (up to ten). They are prevalently localized on the anterior aspect of the legs, less frequently on the trunk, limbs and scalp. Ecthyma syphilitica is considered to be evidence of a malignant course of syphilis and occurs in weakened individuals suffering from tuberculosis and in persons abusing alcohol; it develops no earlier than six months after infection. The clinical picture is marked by a deep pustule, covered with a thick greyish-brown crust, as if pressed into the skin. An ulcer forms under the crust leaving a smooth scar after healing. A hard copper-red infiltrate forms on the periphery of the lesion, which does not occur in ecthyma vulgaris. The favoured localization of ecthyma syphilitica is the anterior aspect of the legs, whereas the common forms of ecthyma are usually found in the small of the back and on the buttocks. Besides, a diffuse redness is encountered around the lesion in ecthyma vulgaris; it may, however, also be found in ecthyma syphilitica complicated by secondary infection. The diagnosis is also difficult to make because in ecthyma syphilitica the serological reactions are often negative as the result of the body's anergy.

Rupia syphilitica is a variant of ecthyma in which a layered conical crust forms. Peripheral growth of the lesion and the presence of a large ulcer under the crust are characteristic features. Rupia develops no earlier than a year after the onset of the disease and, like ecthyma, is evidence of the malignant course of syphilis in the patient.