What is the management and diagnosis for a 23-year-old woman presenting with non-pruritic (non-itchy) rash on her hands, characterized by clearly defined circular lesions with dusky, red, and white centers, and a healing lesion with a scab on her upper lip?

Diagnosis: Secondary Syphilis

This clinical presentation is pathognomonic for secondary syphilis, requiring immediate serologic testing (RPR/VDRL and treponemal-specific tests) and treatment with benzathine penicillin G 2.4 million units intramuscularly as a single dose.

Clinical Features Diagnostic of Secondary Syphilis

The constellation of findings described is classic for secondary syphilis:

• Palmar and dorsal hand lesions with circular, well-defined appearance and dusky red-white centers represent the characteristic papulosquamous eruption of secondary syphilis 1
• Non-pruritic nature distinguishes this from most dermatologic conditions and is typical of syphilitic rashes 1
• Healing lip lesion with scab likely represents a resolving primary chancre, indicating progression from primary to secondary stage 1

The British Association of Dermatologists identifies target or targetoid lesions as requiring differentiation from erythema multiforme, but the absence of pruritus, palmoplantar distribution, and presence of an oral lesion consistent with chancre strongly favor secondary syphilis over other target-lesion diagnoses 1.

Diagnostic Workup

Essential serologic testing includes:

• Non-treponemal tests (RPR or VDRL) for initial screening and quantitative titers 1
• Treponemal-specific tests (FTA-ABS or TP-PA) for confirmatory diagnosis 1
• HIV testing given the epidemiologic association and potential impact on treatment duration 1

Skin biopsy is NOT necessary when clinical presentation is classic, as serologic testing provides definitive diagnosis 1. However, if performed, would show plasma cell infiltrate and spirochetes on special staining.

Management

Benzathine penicillin G 2.4 million units intramuscularly as a single dose is the treatment of choice for secondary syphilis in immunocompetent patients 1.

For penicillin-allergic patients:

• Doxycycline 100 mg orally twice daily for 14 days is the alternative 1
• Penicillin desensitization should be considered in pregnancy 1

Follow-up serologic testing at 6 and 12 months to document adequate response (four-fold decrease in non-treponemal titers) 1.

Critical Pitfalls to Avoid

• Do not dismiss palmar lesions as dermatitis - palmoplantar involvement in a young adult should always prompt consideration of secondary syphilis 1
• Do not rely on pruritus to rule out infectious causes - syphilitic rashes are characteristically non-pruritic 1
• Do not delay treatment pending confirmatory testing if clinical suspicion is high and patient may be lost to follow-up 1
• Screen all sexual contacts from the preceding 3-6 months for epidemiologic treatment 1