Differential Diagnosis for PNC Day 3 VDRL and TPHA Positive

Single Most Likely Diagnosis

• Syphilis: The patient is VDRL (Venereal Disease Research Laboratory test) and TPHA (Treponema pallidum hemagglutination assay) positive, which are specific tests for syphilis. The presence of these antibodies indicates an active or past infection with Treponema pallidum, the bacterium that causes syphilis.

Other Likely Diagnoses

• Congenital Syphilis: Given that it's postnatal care (PNC) day 3, if the mother has syphilis, the newborn could have congenital syphilis, which would explain the positive VDRL and TPHA results.
• False-Positive VDRL with True-Positive TPHA: While less common, it's possible for VDRL to yield false-positive results due to various factors (e.g., autoimmune diseases, other infections), but a positive TPHA would confirm the presence of syphilis antibodies.

Do Not Miss Diagnoses

• Neurosyphilis: Although less likely in a newborn, neurosyphilis is a serious condition that occurs when syphilis infects the central nervous system. It's crucial to consider this diagnosis due to its severe implications and the need for prompt treatment.
• Other Congenital Infections: While the tests are positive for syphilis, it's essential not to miss other congenital infections (e.g., toxoplasmosis, rubella, cytomegalovirus, HIV) that could have similar presentations or be co-infections.

Rare Diagnoses

• Yaws or Bejel: These are other treponemal infections that could potentially cause positive results on non-treponemal tests like VDRL, though they are much rarer and typically have different clinical presentations.
• Laboratory Error: Although rare, laboratory errors can occur, leading to false-positive results. This should be considered if clinical presentation and other diagnostic findings do not align with syphilis.