A 47-year-old man presents with low-grade fever, severe tinea pedis (athlete's foot), patchy alopecia, hyperpigmented maculopapular rash on palms and soles, and lymphadenopathy. What is the most appropriate next step in diagnosis?

From the Guidelines

The most appropriate next step in diagnosis for this 47-year-old man is to perform serologic testing for syphilis, specifically a rapid plasma reagin (RPR) or Venereal Disease Research Laboratory (VDRL) test, followed by a confirmatory treponemal-specific test such as FTA-ABS (fluorescent treponemal antibody absorption) or TP-PA (T. pallidum particle agglutination). This patient's constellation of symptoms—low-grade fever, lymphadenopathy, and particularly the hyperpigmented maculopapular rash on palms and soles—strongly suggests secondary syphilis, as noted in studies such as 1 which mentions that a rash on the palms and soles might occur in illnesses caused by Treponema pallidum. The presence of tinea pedis and patchy alopecia further supports this diagnosis, as secondary syphilis can cause "moth-eaten" alopecia. Secondary syphilis typically appears 4-10 weeks after the primary chancre has healed and represents hematogenous spread of Treponema pallidum. Early diagnosis is crucial as untreated syphilis can progress to tertiary stages with serious neurological, cardiovascular, and other systemic complications. If serologic tests confirm syphilis, treatment would typically involve benzathine penicillin G 2.4 million units intramuscularly as a single dose for early syphilis, with different regimens for later stages or neurosyphilis, prioritizing the reduction of morbidity, mortality, and improvement of quality of life. Other options like blood cultures or lymph node biopsy may be considered in the differential diagnosis but are not the most appropriate next step given the clinical presentation, as discussed in 1 and 1, which highlight the importance of early diagnosis and treatment in similar conditions. It's also worth noting that while other conditions such as tinea capitis, as discussed in 1, can present with alopecia and skin lesions, the specific combination of symptoms in this patient points more strongly towards syphilis.

From the Research

Diagnosis of Syphilis

The patient's symptoms, including low-grade fever, severe tinea pedis, patchy alopecia, hyperpigmented maculopapular rash on palms and soles, and lymphadenopathy, are consistent with secondary syphilis. The most appropriate next step in diagnosis would be to confirm the presence of syphilis through serologic testing.

Serologic Testing for Syphilis

• Serologic tests are the primary method for diagnosing syphilis, as the disease can have varied and subtle clinical manifestations 2, 3, 4, 5.
• The most widely used screening tests for syphilis are the Venereal Disease Research Laboratory (VDRL) and the rapid plasma reagin (RPR) tests, followed by confirmation with treponemal-specific tests such as the fluorescent treponemal antibody (FTA) test or the treponema pallidum hemagglutination (TPHA) test 2, 3, 4.
• Newer diagnostic modalities, including nucleic acid amplification assays (NAATs) and point-of-care testing (POCT), are also available, but their use is not yet widespread 5.
• Automated syphilis tests, such as the HiSens Auto Rapid Plasma Reagin (AutoRPR) and Treponema Pallidum particle agglutination (AutoTPPA) tests, have been shown to be reliable alternatives to conventional tests 6.

Next Steps

Based on the patient's symptoms and the availability of serologic testing, the most appropriate next step in diagnosis would be:

• Serologic testing for syphilis, including a nontreponemal test (such as VDRL or RPR) and a treponemal-specific test (such as FTA or TPHA) 2, 3, 4, 5.
• The correct answer is D) Serologic testing for syphilis.