A Viral Fingertip Infection that Must NOT Be Incised
- Herpetic whitlow is a HERPES SIMPLEX VIRUS infection of the FINGERTIP (pulp/periungual skin), caused by HSV-1 or HSV-2; it characteristically produces a PRODROME of pain, tingling or burning followed by GROUPED VESICLES on an ERYTHEMATOUS base, with pain often OUT OF PROPORTION to the modest swelling.
- It classically affects YOUNG CHILDREN (autoinoculation from oral HSV - e.g. thumb-sucking/herpetic gingivostomatitis), HEALTHCARE WORKERS exposed to oral secretions (dentists, anaesthetists, respiratory staff - now much less common with universal glove use), and adults with genital HSV (HSV-2).
- THE KEY POINT: herpetic whitlow MUST NOT be treated like a felon - it must NOT be INCISED AND DRAINED. The fluid is viral (not pus), and incising it risks BACTERIAL SUPERINFECTION, delayed healing and potentially SYSTEMIC viral spread - a dangerous error, especially in the immunocompromised.
- It is therefore essential to DIFFERENTIATE it from a bacterial FELON (a purulent abscess of the closed pulp space that DOES need incision and drainage) and from acute paronychia: the grouped clear vesicles, the non-purulent vesicular fluid, the prodrome and the relatively soft (non-tense) pulp point to a viral whitlow.
- Diagnosis is usually CLINICAL; it can be confirmed by a TZANCK smear (multinucleated giant cells), HSV PCR (most sensitive/specific), viral culture or direct fluorescent antibody from vesicle fluid - useful when atypical or to avoid an inappropriate incision.
- Management is SUPPORTIVE - analgesia and keeping the lesion clean and COVERED (to prevent autoinoculation/transmission) - and the condition is SELF-LIMITING over about 2-4 weeks; ORAL ANTIVIRALS (aciclovir/valaciclovir) shorten and reduce symptoms, particularly when started EARLY, and are important in severe, recurrent or immunocompromised cases; antibiotics are reserved for proven SECONDARY bacterial infection.
- “Grouped CLEAR vesicles on an erythematous fingertip + pain out of proportion + prodrome = herpetic whitlow (HSV).
- “DO NOT incise & drain (it is viral, not pus) - incision risks superinfection/systemic spread. Felon (purulent pulp abscess) IS drained.
- “Self-limiting (~2-4 weeks); antivirals (aciclovir) help if early/severe/recurrent/immunocompromised; keep covered to prevent autoinoculation.
Grouped clear vesicles on an erythematous base, non-purulent, pain out of proportion, prodrome. Viral - supportive care +/- antivirals. Incising it is harmful.
Tense, throbbing, purulent abscess of the closed pulp space. Bacterial - needs incision & drainage + antibiotics.
Aetiology & Presentation
Herpetic whitlow is inoculation of herpes simplex virus into the skin of the fingertip through a breach. HSV-1 predominates in children (autoinoculation from oral herpes, e.g. thumb-sucking with herpetic gingivostomatitis) and in healthcare workers exposed to oral/respiratory secretions (dentists, anaesthetists, respiratory therapists - historically a classic occupational infection, now uncommon with glove use); HSV-2 affects adults via genital contact. After a prodrome of localised pain, tingling or burning, grouped vesicles appear on an erythematous, oedematous base; the vesicles contain initially clear then cloudy fluid and may coalesce, and the pain is often out of proportion to the swelling. Low-grade fever, lymphangitis and epitrochlear/axillary lymphadenopathy may occur. The virus then becomes latent in the sensory ganglion, so recurrence is possible.
Diagnosis & Management
Diagnosis is usually clinical from the grouped vesicles, prodrome and non-purulent appearance. When atypical - or to avoid an inappropriate incision - confirm with a Tzanck smear (multinucleated giant cells), HSV PCR (most sensitive and specific), viral culture, or direct fluorescent antibody from vesicle fluid. Management:
- Supportive: analgesia, keep the lesion clean and covered with a dry dressing to limit autoinoculation (eye - herpetic keratitis - and genitals) and transmission to others; the condition is self-limiting over about 2-4 weeks.
- Antivirals: oral aciclovir/valaciclovir shorten the episode and symptoms, especially when started early, and are indicated in severe, recurrent or immunocompromised patients; suppressive antivirals may be used for frequent recurrences.
- Do NOT incise and drain - the cardinal rule.
- Antibiotics only for a proven secondary bacterial infection.
Series report herpetic whitlow being misdiagnosed as a bacterial whitlow and incised, or even mistaken for non-accidental injury (cigarette burns) in children. Incising a herpetic whitlow can cause bacterial superinfection, delayed healing and a risk of systemic viral dissemination - dangerous in the immunocompromised. Always consider HSV in a vesicular fingertip lesion, keep it covered to prevent cross-infection and autoinoculation to the eye, and counsel about recurrence.
Evidence & Key Studies
Paediatric recurrent herpetic whitlow
- A child's recurrent herpetic whitlow was initially mistaken for a bacterial whitlow and treated with incision and drainage, and later misattributed to cigarette burns prompting a child-protection referral.
- Correct diagnosis was made by scraping and viral culture, with recovery after topical and systemic aciclovir; recurrence occurred years later.
- Highlights the danger of incorrect diagnosis and inappropriate incision, the risk of cross-infection, and the importance of recognising HSV - especially to protect immunocompromised contacts.
Herpetic whitlow associated with an eating disorder: a case report
- Herpetic whitlow is a localised cutaneous HSV-1/HSV-2 infection of the fingers that can be recurrent, here linked to autoinoculation behaviour.
- It presented as an eroded group of vesicles on an erythematous base and was diagnosed clinically from history and examination.
- It resolved within a week of topical and systemic aciclovir, illustrating the supportive/antiviral (non-surgical) management.
According to PubMed, the danger of misdiagnosis and inappropriate incision (and the diagnosis by viral culture, treatment with aciclovir and tendency to recur) comes from the cited Patel case report, and the HSV-1/HSV-2 aetiology, grouped-vesicle presentation, clinical diagnosis and aciclovir response from the cited Aljehani report. The no-incision rule and the felon/paronychia differentiation are standard hand-surgery teaching. (See also our Felon, Paronychia and Hand Infections topics.)
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“A patient presents with a painful, blistered, red fingertip. How do you tell a herpetic whitlow from a felon, and why does it matter?”
“Who gets herpetic whitlow, how would you treat it, and what complications would you warn about?”
Mnemonics & Memory Aids
WHITLOW
Hook:Every letter of WHITLOW says: viral, don't cut it, cover it, antivirals.
CLEAR vs PUS
Hook:CLEAR vesicles = leave it (viral); PUS = drain it (felon).
What it is
- HSV-1/HSV-2 infection of the fingertip (pulp/periungual)
- Prodrome (pain/tingling) -> grouped vesicles on erythema; pain out of proportion
- At risk: children (oral autoinoculation), healthcare workers, adults with genital HSV
Differentiation
- Whitlow: grouped CLEAR vesicles, non-purulent (viral)
- Felon: tense PURULENT closed-pulp abscess (bacterial) - needs I&D
- Confirm HSV if unsure: Tzanck, PCR, culture, DFA
Management
- DO NOT incise & drain (risks superinfection/systemic spread)
- Supportive: analgesia, keep covered (prevent autoinoculation); self-limiting ~2-4 weeks
- Oral aciclovir/valaciclovir if early/severe/recurrent/immunocompromised; antibiotics only for 2ndary infection
Complications
- Autoinoculation (eye - herpetic keratitis; genitals)
- Secondary bacterial infection; systemic spread (immunocompromised)
- Recurrence (latency in sensory ganglion)