Introduction
  Background
 Syphilis is an infectious disease caused by the spirochete 
Treponema pallidum.  Syphilis is transmissible by sexual contact with infectious lesions  from mother to fetus in utero, via blood product transfusion, and  occasionally through breaks in the skin that come into contact with  infectious lesions.
Syphilis  has a myriad of presentations and can mimic many other infections and  immune-mediated processes in advanced stages. Hence, it has earned the  nickname "the great impostor." The complex and variable manifestations  of the disease prompted Sir William Osler to remark that, "The physician  who knows syphilis knows medicine."
Many famous personages  throughout history are thought to have suffered from syphilis, including  Bram Stoker, Henry VIII, and Vincent Van Gogh. Since the discovery of  penicillin in the mid-20th century, the spread of this once very common  disease has been largely controlled, but efforts to eradicate the  disease entirely have been unsuccessful.
 Pathophysiology
 T pallidum  is a fragile spiral bacterium 6-15 micrometers long by 0.25 micrometers  in diameter. Its small size makes it invisible on light microscopy;  therefore, it must be identified by its distinctive undulating movements  on darkfield microscopy. It can survive only briefly outside of the  body; thus, transmission almost always requires direct contact with the  infectious lesion.
T pallidum penetrates abraded skin or  intact mucous membranes easily and disseminates rapidly, although  asymptomatically, via the blood vessels and lymphatics.
Primary  syphilis is characterized by the development of a painless chancre at  the site of transmission after an incubation period of 3-6 weeks. The  lesion has a punched-out base and rolled edges and is highly infectious.  It resolves 4-6 weeks after it forms and does not typically leave a  scar.
Secondary syphilis develops about 4-10 weeks after the  appearance of the primary lesion and has a wide range of presentations.  During this stage, the spirochetes multiply and spread throughout the  body. Systemic manifestations include malaise, fever, myalgias,  arthralgias, lymphadenopathy, and rash. The rash of secondary syphilis  typically consists of macular lesions symmetrically distributed over the  body and may involve the palms, soles, and oral mucosae. Atypical  appearances include papular or even pustular lesions.
Other skin  findings of secondary syphilis are condylomata latum and patchy  alopecia. Condylomata latum are painless, highly infectious gray-white  lesions that develop in warm, moist sites; these are shown in the image  below.

Condylomata lata.

Condylomata lata.
The  alopecia is characterized by patchy hair loss of the scalp and facial  hair, including the eyebrows. Patients with this finding have been  referred to as having a "moth-eaten" appearance. During secondary  infection, the immune reaction is at its peak and antibody titers are  high.Latent syphilis is a stage at which the features of secondary  syphilis have resolved, though patients remain seroreactive. Some  patients experience recurrence of the infectious skin lesions of  secondary syphilis during this period. About one third of untreated  latent syphilis patients go on to develop tertiary syphilis, whereas the  rest remain asymptomatic.
Tertiary syphilis develops over months  to years and involves slow inflammatory damage to tissues including  nerves and blood vessels. The 3 general categories of tertiary syphilis  are gummatous syphilis (also called late benign), cardiovascular  syphilis, and neurosyphilis.
Gummatous syphilis is characterized  by granulomatous lesions, called gummas, which are mainly found in the  skin, bones, and liver, but may affect any organ. They may break down  and form ulcers, eventually becoming fibrotic. These lesions are  noninfectious.
Cardiovascular syphilis occurs at least 10 years  after primary infection. The most common manifestation is aneurysm  formation in the ascending aorta, caused by chronic inflammatory  destruction of the vasa vasorum, the penetrating vessels that nourish  the walls of large arteries. Aortic valve insufficiency may result.
Neurosyphilis  has several forms. If the spirochete invades the central nervous system  (CNS), syphilitic meningitis results. Syphilitic meningitis is an early  manifestation, usually occurring within 6 months of the primary  infection. Cerebrospinal fluid (CSF) shows high protein, low glucose,  high lymphocyte count, and positive syphilis serology.
Meningovascular  syphilis occurs as a result of damage to the blood vessels of the  meninges, brain, and spinal cord, leading to infarctions causing a wide  spectrum of neurologic impairments. Tabes dorsalis develops as the  posterior columns and dorsal roots of the spinal cord are damaged.  Posterior column impairment results in impaired vibration and  proprioceptive sensation, leading to a wide-based gait.
Disruption  of the dorsal roots leads to loss of pain and temperature sensation and  areflexia. Damage to the cortical regions of the brain leads to general  paresis, formerly called "general paresis of the insane," which mimics  other forms of dementia. Impairment of memory and speech, personality  changes, irritability, and psychotic symptoms develop and may advance to  progressive dementia. The Argyll-Robertson pupil, a pupil that does not  react to light but does constrict during accommodation, may be seen in  tabes dorsalis and general paresis. The precise location of the lesion  causing this phenomenon is unknown.
Congenital syphilis,  discussed briefly here, is a veritable potpourri of antiquated medical  terminology. The treponemes readily cross the placental barrier and  infect the fetus, causing a high rate of spontaneous abortion and  stillbirth. Within the first 2 years of life, symptoms are similar to  severe adult secondary syphilis with widespread condylomata latum and  rash. "Snuffles" describes the mucopurulent rhinitis caused by  involvement of the nasal mucosae.
Later manifestations of  congenital syphilis include bone and teeth deformities including "saddle  nose" due to destruction of the nasal septum, "saber shins" due to  inflammation and bowing of the tibia, "Clutton's joints" due to  inflammation of the knee joints, "Hutchinson's teeth" in which the upper  incisors are widely spaced and notched (shown in the image below), and  "mulberry molars" in which the molars have too many cusps.

Syphilis. This photograph shows an example of     Hutchinson teeth in congenital syphilis. Note notching. Used     with permission from Wisdom A. Color Atlas of Sexually     Transmitted Diseases. Year Book Medical Publishers Inc;     1989.

Syphilis. This photograph shows an example of     Hutchinson teeth in congenital syphilis. Note notching. Used     with permission from Wisdom A. Color Atlas of Sexually     Transmitted Diseases. Year Book Medical Publishers Inc;     1989.
Tabes dorsalis and general paresis may  develop as in adults, with 8th cranial nerve deafness and optic nerve  atrophy as well as a variety of other ophthalmologic involvement leading  to blindness being additional features.
 Frequency
 United States
 Since  reporting began in 1941, the incidence of primary and secondary  syphilis in the United States has varied. The incidence dropped from  66.4 cases per 100,000 in 1947 to 3.9 cases per 100,000 in 1956  following the introduction of penicillin, reaching its lowest point ever  in 2000 with 2.1 cases per 100,000. Since then, rates have increased  again to 2.7 per 100,000 in 2004, primarily due to an increased  incidence amongst men who have sex with men (MSM).
1 International
 Internationally,  the prevalence of syphilis varies by region, the highest rates being in  South and Southeast Asia, followed closely by sub-Saharan Africa. The  third highest rates are in the regions of Latin America and the  Caribbean.
2  Mortality/Morbidity
 The  morbidity and mortality of untreated syphilis must be estimated from  the limited data available regarding its natural course. These data are  largely from one retrospective study of autopsies and two prospective  studies, most notably the famous Tuskegee Study of Untreated Syphilis in  the Negro Male, which fell under serious ethical scrutiny in later  years for exploiting a vulnerable patient population and not offering  treatment for the disease when it became available after the study was  underway. These data indicate that approximately one third of patients  left untreated will develop late complications, with 10% of the total  developing cardiovascular syphilis; 6%, neurosyphilis; and 16%,  gummatous syphilis. Mortality rates in general are greater among those  affected, and late complications appear to occur more commonly in men  than in women.
3,4  Race
 Racial  disparities exist, with blacks affected more frequently than whites. In  2004, the rate among blacks was 5.6 times higher than the rate among  whites.
1  Sex
 Men are affected more frequently with primary or secondary syphilis than women. The male-to-female ratio is 5.9.
1  In 2007, 65% of of new cases occurred in men who have sex with men, and there is a high rate of HIV co-infection.
5  Age
 In 2007, the rate of primary and secondary syphilis was highest in people aged 25-29 years (8.9 per 100,000).
5  Clinical
  History
 Because  the manifestations of syphilis (particularly advanced syphilis) are  nonspecific and may masquerade as many other diseases, the physician  must keep a high index of suspicion regarding the possible diagnosis of  syphilis.
The clinician should carefully reconstruct the time  course and description of all symptoms and lesions and obtain a complete  sexual history including history of STDs, condom use, and the number  and gender of previous sexual partners.
The United States  Preventive Services Task Force (USPSTF) issued screening guidelines to  include all pregnant women and people at risk of acquiring syphilis.
The  US Preventive Services Task Force has reaffirmed its recommendation for  screening all pregnant women for syphilis infection at the first  prenatal visit. High-risk women (eg, uninsured women, women living in  poverty, sex workers, illicit drug users, those with other sexually  transmitted diseases including HIV, those living in communities with  high syphilis incidence) should also be tested in the third trimester of  pregnancy and at delivery. If test results are positive for syphilis,  the treatment of choice is parenteral benzathine penicillin G. Dosage  and length of treatment depend on the stage and clinical manifestations  of the disease.
6 - Primary syphilis
- Genital  chancre - Frequently solitary, may be multiple (Sometimes seen as  "kissing" lesions on opposing skin surfaces, for example, the labia.  This is shown in the image below.)
 

Syphilis. This photograph depicts primary     syphilis "kissing" lesions. Used with permission from Wisdom A.     Color Atlas of Sexually Transmitted Diseases. Year Book Medical     Publishers Inc; 1989.

Syphilis. This photograph depicts primary     syphilis "kissing" lesions. Used with permission from Wisdom A.     Color Atlas of Sexually Transmitted Diseases. Year Book Medical     Publishers Inc; 1989.
- A chancre appears 3-6 weeks after initial sexual contact.
 
 - Secondary syphilis
- Rash - Nonpruritic and bilaterally symmetrical 
 - Patchy alopecia
 - Condylomata latum, shown in the image below
 

These photographs illustrate examples of     condylomata lata. The lesions resemble genital warts     (condylomata acuminata). Fluids exuding from these lesions are     highly infectious. Used with permission from Wisdom A. Color     Atlas of Sexually Transmitted Diseases. Year Book Medical     Publishers Inc; 1989.

These photographs illustrate examples of     condylomata lata. The lesions resemble genital warts     (condylomata acuminata). Fluids exuding from these lesions are     highly infectious. Used with permission from Wisdom A. Color     Atlas of Sexually Transmitted Diseases. Year Book Medical     Publishers Inc; 1989.
- Constitutional symptoms of secondary syphilis include malaise, sore throat, headache, fever, anorexia, and, rarely, meningismus.
 
 - Tertiary syphilis
- Altered mental status
 - Focal neurologic findings, including sensorineural hearing and vision loss
 - Dementia
 - Patients may have symptoms related to the cardiovascular or central nervous systems.
 
 
 Physical
 Conduct  the physical examination with the manifestations of primary, secondary,  and tertiary syphilis in mind. The lesions and exanthem of primary and  secondary syphilis are infectious; thus, gloves and other relevant  personal protective equipment must be worn.
- Primary syphilis
- The  chancre of primary syphilis usually begins as a single, painless papule  that rapidly becomes eroded and indurated. The ulcer has a  cartilaginous consistency at the edge and base. A lesion is shown in the  image below.
 

Syphilitic chancre.

Syphilitic chancre.
- Chancres  usually are located on the penis in heterosexual men, but, in  homosexual men, they may be found in the anal canal, mouth, or external  genitalia. Common primary sites in women include the cervix and labia.
 - Atypical primary lesions are common and may manifest as a papular lesion without subsequent ulceration or induration.
 - The  primary lesion usually is associated with regional lymphadenopathy that  may be unilateral or bilateral. Inguinal adenitis is usually discrete,  firm, mobile, and painless, without overlying skin changes.
 
 - Secondary syphilis
- Secondary  syphilis may present in many different ways but usually includes a  localized or diffuse mucocutaneous rash and generalized nontender  lymphadenopathy. The exanthem may be macular, papular, pustular, or  mixed.
 - Typical early lesions are usually less than (20 size or  number), round, discrete, nonpruritic, and symmetric macules distributed  on the trunk and proximal extremities. Red papular lesions also may  appear on the palms, soles, face, and scalp and may become necrotic.  Patchy and nonpatchy alopecia may occur. In intertriginous areas,  papules may coalesce to form highly infectious lesions called  condylomata lata. Lesions usually progress from red, painful, and  vesicular to "gun metal grey" as the rash resolves. Examples of the rash  are shown in the images below.
 

Secondary syphilis - Exanthem.

Secondary syphilis - Exanthem.

Secondary syphilis - Exanthem.

Secondary syphilis - Exanthem.
- Mucous  patches are superficial mucosal erosions, usually painless, that may  develop on the tongue, oral mucosa, lips, vulva, vagina, and penis.
 - Other,  less common manifestations of secondary syphilis include  gastrointestinal involvement, hepatitis, nephropathy, proctitis,  arthritis, and optic neuritis.
 
 - Tertiary syphilis
- Symptomatic  tertiary syphilis is the result of a chronic, progressive inflammatory  process that eventually produces clinical symptoms years to decades  after the initial infection.
 
 - Gummatous syphilis  manifests as coalescent granulomatous lesions that usually affect skin,  bone, and mucous membranes but may involve any organ system. The lesions  often cause local destruction of the affected organ system. Gummas in  tertiary syphilis are shown in the image below.
 

Syphilis. These photographs show close-up images     of gummas observed in tertiary syphilis. Used with permission     from Wisdom A. Color Atlas of Sexually Transmitted Diseases.     Year Book Medical Publishers Inc; 1989.

Syphilis. These photographs show close-up images     of gummas observed in tertiary syphilis. Used with permission     from Wisdom A. Color Atlas of Sexually Transmitted Diseases.     Year Book Medical Publishers Inc; 1989.
- Cardiovascular  syphilis results from endarteritis of the aorta, subsequent medial  necrosis, aortitis, and aneurysm formation. Other large arteries may be  affected as well.
 - Neurosyphilis  may be asymptomatic or symptomatic. In asymptomatic neurosyphilis, no  signs or symptoms are present, but CSF abnormalities are demonstrable,  including possible pleocytosis, elevated protein, decreased glucose, or a  reactive CSF Venereal Disease Research Laboratory (VDRL) test.
- Symptomatic neurosyphilis may manifest as syphilitic meningitis, meningovascular syphilis, or parenchymatous neurosyphilis.
 - Syphilitic  meningitis usually develops within 6 months to several years of initial  infection, and patients present with typical symptoms of meningitis,  including headache, nausea and vomiting, and photophobia, but are  typically afebrile. Patients may exhibit cranial nerve abnormalities.
 - Meningovascular  syphilis manifests 5-10 years after infection and is the result of  endarteritis, which affects small blood vessels of the meninges, brain,  and spinal cord. Patients may present with CNS vascular insufficiency or  outright stroke.
 - Parenchymatous neurosyphilis results from direct parenchymal CNS invasion by T pallidum and is usually a late development (15-20 years after primary infection).
 - Patients  present with ataxia; incontinence; paresthesias; and loss of position,  vibratory, pain, and temperature sensations. Paresis and dementia, with  changes in personality and intellect, may develop.