Immunocompromised Child with Rash on Buttocks and Tongue
This presentation is most consistent with disseminated herpes simplex virus (HSV) infection, and immediate treatment with intravenous acyclovir 5-10 mg/kg/dose three times daily for 7-14 days is strongly recommended. 1
Clinical Recognition
The combination of oral and perianal/buttock lesions in an immunocompromised child should immediately raise concern for:
- HSV infection with mucocutaneous dissemination - In immunocompromised patients, HSV episodes are typically longer and more severe, potentially involving the entire oral cavity or extending across other body surfaces including the buttocks 2, 1
- Oral involvement (tongue) suggests herpetic gingivostomatitis, which presents with painful ulcers in the gingival and oral mucosa, fever, irritability, and tender submandibular lymphadenopathy 2, 3
- Buttock involvement indicates extension beyond typical orolabial distribution, which is characteristic of HSV in immunocompromised hosts 1
Immediate Diagnostic Approach
Do not delay treatment while awaiting laboratory confirmation - clinical suspicion in an immunocompromised child warrants immediate empiric therapy. However, obtain diagnostic specimens before starting treatment: 1, 3
- Viral culture from vesicle fluid or ulcer base (both oral and buttock lesions) - detectable within 1-3 days 3
- HSV DNA PCR if available (most sensitive method) 3
- Clinical diagnosis based solely on appearance is unreliable, particularly in immunocompromised children where atypical presentations are common 3
Treatment Protocol
For immunocompromised children with mucocutaneous HSV:
- Intravenous acyclovir 5-10 mg/kg/dose three times daily for 7-14 days is the recommended first-line treatment 1
- HIV-infected children with severe immunocompromise may experience more frequent and severe recurrences with potential for disseminated disease involving multiple organs, requiring the full 14-day course 2
- Treatment duration should be extended if lesions have not completely healed by day 7 1
Critical monitoring during acyclovir therapy:
- Monitor for neutropenia, phlebitis, renal toxicity, nausea, vomiting, and rash 1
- Dose adjustment required based on creatinine clearance in patients with renal insufficiency 1
- Ensure adequate hydration to prevent acyclovir-induced nephrotoxicity 1
Differential Considerations
While HSV is most likely, briefly consider:
- Disseminated varicella - but immunocompromised children should not have received live varicella vaccine 4
- Candidiasis - oral thrush can occur on tongue, but buttock involvement would suggest candidal diaper dermatitis; however, this typically doesn't present with discrete vesicular/ulcerative lesions 5
- Disseminated histoplasmosis - can cause oral and skin lesions in immunocompromised children, but presentation is usually more systemic with fever and hepatosplenomegaly 4
The vesicular/ulcerative nature of lesions in both oral and perianal distribution strongly favors HSV over fungal etiologies.
Critical Pitfalls to Avoid
- Never assume HSV can be ruled out based on clinical appearance alone - atypical presentations are common in immunocompromised hosts and laboratory confirmation is essential 3
- Do not delay antiviral therapy while awaiting culture results - peak viral titers occur in the first 24 hours after lesion onset, and early treatment improves outcomes 2
- Do not use oral acyclovir as initial therapy in immunocompromised children with disseminated disease - IV route is required for adequate drug levels 1
- Do not discontinue therapy prematurely - immunocompromised children require longer treatment courses than immunocompetent hosts 2, 1