CPT Code for Varicella-Zoster Virus Lesion Testing
For a lesion scrape or swab for Varicella-Zoster Virus (VZV) DNA detection via PCR in an immunocompromised patient, the appropriate CPT code is 87798 (Infectious agent detection by nucleic acid [DNA or RNA], not otherwise specified; amplified probe technique, each organism).
Specimen Collection and Testing Approach
Optimal Specimen Types for VZV Detection
- Vesicular or macular/papular lesion specimens are the gold standard for VZV diagnosis, with PCR sensitivity of 95-100% when collected at rash onset 1
- Lesion swabs or scrapes should be obtained from the base of fresh vesicles or early macular/papular lesions for maximum viral DNA yield 1, 2
- In immunocompromised patients specifically, VZV DNA detection rates in skin lesions approach 100% during active infection 3
Alternative Specimen Considerations
- Oral/throat swabs can be considered as supplementary specimens, particularly in immunocompromised patients where VZV DNA was detected in 60% of throat swabs within two weeks of rash onset 4
- However, oral swab sensitivity (74.2%) is significantly lower than skin lesion specimens and should not replace dermal sampling 2
- Blood specimens (whole blood, plasma, or serum) show detection rates of 81-100% in immunocompromised patients with herpes zoster, emphasizing the risk of disseminated disease in this population 3
Clinical Context for Immunocompromised Patients
Diagnostic Urgency
- Laboratory confirmation is specifically needed for immunocompromised patients with atypical clinical presentations, as clinical diagnosis alone should not be relied upon in this population 5
- PCR testing of vesicle fluid is the gold standard with nearly 100% sensitivity and specificity 5
- Treatment should be initiated immediately upon clinical suspicion without waiting for laboratory confirmation 5
Timing of Specimen Collection
- Specimens should be collected as early as possible after rash onset for optimal diagnostic yield 1
- Viral shedding peaks in the first 24 hours after lesion onset when most lesions are vesicular 6
- In immunocompromised patients, lesions may continue to develop over 7-14 days, providing a longer window for specimen collection compared to immunocompetent hosts 6
Additional CPT Codes to Consider
- 87252 may be used for direct fluorescent antibody (DFA) testing of skin lesions, though this has lower sensitivity than PCR 7
- 87798 remains the most appropriate code for VZV PCR from any specimen type (lesion, oral, blood)
- If multiple specimen types are tested simultaneously (e.g., lesion swab plus blood), each PCR test would be coded separately with 87798
Common Pitfalls to Avoid
- Do not rely on serologic testing (IgM/IgG) for acute diagnosis, as serology is not useful for diagnosing active shingles 5
- Avoid collecting specimens after lesions have completely crusted, as viral DNA yield decreases significantly 1
- Do not use oral swabs as the sole specimen type for breakthrough varicella diagnosis, as sensitivity is inadequate 2