Syphilis Differential Diagnosis Table

Syphilis Differential Diagnosis Table:

Syphilis is an infectious disease caused by the spirochete Treponema pallidum, a bacterium transmitted primarily through sexual contact and vertically from mother to baby. It can also be transmitted by accidental direct inoculation (needle accidents, fresh blood transfusion, and tattoos).
It can easily be mistaken for other STDs such as scabies, chancroid, etc., and as such, it can be called an imposter disease. Its earliest symptoms include an initial firm, painless, non-itchy skin ulcer on the penis for males and on the vulva for females, which heals with or without treatment after 2-4 weeks (primary syphilis) and gives a false impression of the severity of the long-term complications of this disease.
Other symptoms depend on the different stages of the disease, including secondary, latent, tertiary, or quaternary syphilis. In secondary syphilis, symptoms include a mucocutaneous rash, usually non-pruritic and bilateral, generalized non-tender lymphadenopathy, patchy alopecia, condylomata lata, and other constitutional symptoms such as malaise, headache, anorexia. Symptoms of tertiary syphilis include cardiac, ophthalmic, and auditory abnormalities, as well as gummatous lesions. In quaternary syphilis, there is involvement of the brain as in neurosyphilis. Latent syphilis is a period of no symptoms after secondary syphilis.
Diagnosis can be made by blood tests, darkfield microscopy, rapid plasma reagin tests, etc.

How To Distinguish Syphilis from Drug Other Diseases

Distinguish Exanthematous Drug Eruptions from Syphilis – Diagnosis

These are skin lesions or rashes that result from allergic reactions of the body to certain traditional pharmaceutical agents, biologic agents, and targeted immunotherapeutic agents, food additives, and dye.

• Without prior knowledge of the possibility of the reactions, it’s possible for clinicians to confuse the lesions with some other disease like syphilis.
• Moreover, for syphilis, the initial ulcers are located mainly on the anogenital region, while the rashes for drug eruptions are generalized and symmetrical.

Distinguish Pityriasis Rosea from Syphilis – Diagnosis

Pityriasis Rosea is a skin rash; it classically begins with a single red and slightly scaly area known as a Herald patch. It is then followed by many smaller scaly spots, pinkish in the red edge in people with light skin, greyish in darker skin in the following days to weeks after the observation of the Herald’s patch.

• Although Pityriasis Rosea may be mistaken for secondary syphilis, the differentiation from syphilis would be based on the absence of genital ulcers and lymphadenopathy, and the presence of a herald patch.
• And also, a biopsy of the lesion will reveal extravasated erythrocytes within the dermal papillae and dyskaryotic cells within the dermis.

Distinguish Viral Exanthem from Syphilis – Diagnosis

A viral exanthem is a skin rash that accompanies a viral infection. It presents as spots, bumps, or blotches on the skin. In addition to the skin lesions, other constitutional symptoms of viral infection can also be experienced, such as fever, fatigue, and body aches.

• The rash can begin anywhere on the body, often on the face or trunk, and then spread.

Distinguish Herpes Simplex from Syphilis – Diagnosis

Herpes simplex is an infection caused by the Herpes simplex virus (HSV), which could be either HSV-1 or HSV-2. HSV-1 infection mainly manifests with lesions commonly known as cold sores, while HSV-2 mainly manifests as painful small blisters around the genitals, buttocks, and anus. There could also be other symptoms such as fever, malaise, headache, myalgia, etc.

• Although herpes presents with skin lesions just like syphilis, the lesions in herpes are smaller in size and painful compared to syphilis lesions, which are painless.

Distinguish Scabies from Syphilis – Diagnosis

Scabies is an infectious skin disease that affects dogs and other animals. It is caused by infestation by the mite Sarcoptes scabiei after close contact with an infected individual. The most common symptoms are severe itchiness and a pimple-like rash, and occasionally, tiny burrows may appear on the skin.

• Although scabies and syphilis can be transmitted from person to person through sexual intercourse, and both diseases have cutaneous manifestations, syphilis has much greater consequences if not properly treated.
• The difference is a higher degree of itchiness associated with the scabetic rash and its resolution when treated with medicated skin creams.

Distinguish Candidiasis from Syphilis – Diagnosis

Candidiasis is a fungal infection caused by an overgrowth of a type of yeast, Candida albicans, that lives in the body of human beings. Candidiasis often appears on the skin, vagina, or mouth, where the fungi Candida are part of the normal flora and present in small amounts. Risk factors include stress, a weak immune system, and uncontrolled medical conditions like diabetes mellitus.

• The commonest similarity between candidiasis and syphilis is cutaneous candidiasis, a common example is diaper rash.

Distinguish Chancroid from Syphilis – Diagnosis

Chancroid is a bacterial sexually transmitted infection caused by infection with Haemophilus ducreyi. It is characterized by painful, necrotizing genital ulcers that may be accompanied by enlarged lymph nodes. It is a highly contagious but curable disease.

• Chancroids are commonly diagnosed in men and present with painful erythematous genital ulcerations, usually on the prepuce, coronal sulcus, or glans. Women mostly present with asymptomatic disease manifesting with non-ulcerative symptoms, including vaginal discharge or bleeding, and pain while defecating, urinating, or during intercourse. Women rarely develop ulcers on the labia majora or labia minora.

Distinguish Condyloma Acuminata from Syphilis – Diagnosis

Condyloma Acuminata, also called anogenital warts, represents one of the most common sexually transmitted infections (STI) caused by the low-risk strain of Human Papilloma Virus (HPV 6 and 11). HPV is a DNA virus that is a member of the Papovirus group. It is most commonly seen in the homosexual population.

• In many cases, the warts are too small/flat to be visible, but in advanced cases, the lesions present as pruritic small, flesh-colored bumps or have a cauliflower-like appearance on moist surfaces, usually the genital mucosa (penis, vulva, vagina, cervix, perineum, and peri-anal area).
• Unlike syphilis, the lesions of condyloma acuminata are itchy and may also be present in the throat of a person who has had oral sexual contact with an infected person.

Distinguish Lichen Planus from Syphilis – Diagnosis

Lichen planus is an autoimmune inflammatory condition of the skin and mucous membranes in the body.

• It presents as purplish, itchy, flat-topped bumps/rashes on the skin of the arms, legs, scalp, nails, and genital area.
• On mucous membranes such as the mouth, it forms lacy white patches and sometimes painful sores. Unlike syphilis, it is not an infectious disease.

Important Red Flags in Syphilis

Syphilis is a sexually transmitted infectious disease that can cause serious health problems without proper treatment, despite the fact that it may be asymptomatic in many of its carriers.

The infection develops in stages: primary, secondary, latent, and tertiary, and each stage presents with different symptoms, which makes it mimic other non-fatal infections.
Primary syphilis, which presents with a round, painless, hard sore on the genitals, could easily be misdiagnosed as chancroid, condyloma acuminata, or even herpes simplex.
Secondary syphilis, presenting with a non-itchy rash, usually on the palms and soles of the feet, could be misdiagnosed as viral exanthem and drug eruption.

In conclusion, because of the fatality of untreated syphilis, a detailed history, thorough physical examination, and proper investigation of any and all patients presenting with symptoms suggestive of any stage of syphilis need to be carried out before making a diagnosis.