An infectious disease caused by Treponema pallidum Syphilis, 'the great imitator', is among the most fascinating of skin diseases.

Stages. The clinical presentation of syphilis is extremely diverse and may occur decades after initial infection. Syphilis, if untreated, may pass through four stages: primary, secondary, latent and late. The first two stages are contagious. They seldom last more than 2 years and do not exceed 4 years. Latency may last from 5 to 50 years. Only 25-30% of patients present with late, chronic. in many countries they are now rare.

Course of untreated syphilis • 24% developed mucocutaneous relapses • 11 % died of syphilis • 16% developed benign late manifestations, usually cutaneous nodules or gummata • 10% developed cardiovascular syphilitic lesions • 6% developed neurosyphilis. It would appear therefore that long before the arsenicals and penicillin were introduced, at least 60% of people with syphilis lived and died without developing serious symptoms of their infections.

Primary syphilis Initial lesions are papular but rapidly ulcerate The primary chancre appears at the site of initial treponemal invasion of the dermis. In most cases, there is only a single chancre Initial lesions are papular but rapidly ulcerate It may occur on any skin or mucous membrane surface and is usually situated on the external genitalia. The typical primary sore appears as a regularly edged, regularly based, hard and button-like ulceration measuring up to 1 cm in diameter.

In men, the chancre most usually occurs on the glans penis, Less common sites are the pubic region primary lesion may be on or in the cervix. The most common sites for a vulvar chancre are the labia minora or majora

Unless secondarily infected, primary sores are not painful. The ulcer is often surrounded by a narrow, red border1-2 mm wide. This marks the limits of the inflammatory reaction and is most productive of T. pallidum. 'Kissing' ulcers, sometimes hourglass in shape, are not Uncommon If the infection is inoculated into pre-existing lesions such as anal fissure , genital herpes or balanitis, the chancre may assume the shape of these conditions

Without treatment, the chancre persists for a period that can vary considerably, but seldom, if ever, exceeds 3 months As a rule, it heals spontaneously in 3-8 weeks. In about one-third of cases, it leaves a regularly edged, slightly depressed, thin, depigmented, atrophic scar

Extragenital chancres may be found on the lips

Secondary syphilis Secondary syphilis is the stage when generalized manifestations occur on the skin and mucous membranes. Serological tests are always positive in immunocompetent persons The manifestations of generalized treponemal dissemination first appear at around 8 weeks. Rashes in secondary syphilis have three common features: 1 they do not itch 2 they are coppery red 3 the lesions are symmetrically distributed

Constitutional symptoms consist of fever, headache, and bone and joint pains that are more pronounced at night

Macular syphilide (roseolar rash). It appears as symmetrical, coppery red, round and oval Spots The patients should be examined in daylight

pattern of depigmented spots on a hyperpigmented background. Such a leukoderma syphiliticum is most commonly located on the back or sides of the neck

Papular syphilide. The papule is the basic lesion of secondary syphilis. Individual papules seldom exceed 0.5 cm in diameter. The typical papule is firm and round, although the largest may be oval. Early papules tend to be shiny, but gradually a thin layer of scale forms and is quickly shed. This is the typical papulosquamous syphilide .

In the late phases of a papular syphilide, nummular lesions, 1-3 cm in diameter and covered by massive layers of scales, may closely resemble psoriasis. Because the underlying lesions are exuding serum, the scales are easily removed. Psoriasiform papules of the palms and soles are especially common in black people

may resemble granuloma annulare, annular sarcoid or scaly varieties of tinea.

On macerated skin surfaces and mucous membranes, eroded weeping papules with a tendency to hypertrophy often appear

On the genitals, for example, at the penoscrotal junction, there may be small eroded papules or hypertrophic, papules (condylomata lata).

Hypertrophic papules between the toes may resemble severe tinea pedis

Patchy hair loss is characteristic of syphilis. Syphilitic alopecia. Patchy hair loss is characteristic of syphilis. The hair falls leaving small, scattered, irregularly thinned, 'motheaten' patches of semi-baldness.

Tertiary syphilis After a period of latency of up to 20 years, manifestations of late syphilis can occur. Late skin syphilis appears in two types: the superficial or nodular syphilide and a deeper gummatous syphilide

Nodular or tubercular syphilide . The lesions are protruding, firm, coppery red nodules (larger than 0.5 cm diameter). The nodules appear in groups with a tendency to a circinate arrangement , that is forming interwoven circles and part of circles.

Gumma . The characteristic lesions of tertiary syphilis appear 3-10 years after infection and consist of granulomas or gummata. They have a tendency for central necrosis and ulceration and for peripheral healing with tissue-paper scarring. They most often originate in the subcutis, growing in all directions

Gummata which start in bone or muscle also tend to ulcerate the skin, and their true origin may be difficult to determine

Standard non-treponemal tests. The non-treponemal tests detect IgM and IgG antibodies to lipoidal material released from damaged host cells and to lipoidal-like antigens of T. pallidum . There are 4 tests available .(VDRL) . The rapid plasma reagin (RPR) test and toluidine red unheated serum test (TRUST) The unheated serum reagin (USR) test is similar to the VDRL

Treponemal antigen tests. Specific treponemal antibody tests are used for confirmatory testing. They detect antibodies to antigenic determinants of treponemes. The fluorescent treponemal antibody absorption (FTA-ABS) test and the FTA-ABS double-staining (FTA-ABS DS) test are both indirect immunofluorescent tests.