Infant With Red Swollen Index Finger

THE CASE: A 12-month-old infant is brought to your office for evaluation of a red, swollen left index finger, which her parents first noted the prior evening. The mother denies any known trauma or recent illness. She tells you that the infant is slightly fussy and is not taking her bottle as well as usual. What are your concerns as you inspect this infant’s hand?

•Paronychia
•Herpetic whitlow
•Cellulitis
•Felon

(Answer and discussion begin on next page.)

DISCUSSION: This infant has herpetic whitlow. The infection was first described by Adamson in 1909; in 1959, it was first reported to be an occupational risk among health care workers. Often misdiagnosed as a bacterial infection, herpetic whitlow is caused by herpes simplex virus 1 (HSV-1) in approximately 60% of cases and by herpes simplex virus 2 (HSV-2) in the remaining 40%. Children are usually affected by HSV-1. Autoinoculation occurs from primary oropharyngeal lesions as a result of thumb or finger sucking in patients with herpetic gingivostomatitis or herpes labialis. In adults, herpetic whitlow usually is caused by HSV-2 secondary to autoinoculation from genital herpes.

Physical examination usually reveals 1- to 3-mm grouped vesicular lesions or ulcers with surrounding erythema of the terminal phalanx (Figure 1). The digit is often swollen and tender to palpation. Tingling or burning of the affected digit may be an initial complaint. Vesicular fluid may be hemorrhagic or cloudy, although it is usually clear. Epitrochlear and axillary nodes may be present and lymphangitic streaking (see Figure 1) can be present. Examination of the oral cavity (Figure 2) or genital region often reveals concurrent herpetic lesions

Diagnostic tests and therapy. Although the diagnosis is usually based on clinical examination and history, a variety of laboratory tests are available for definitive diagnostic testing. These include viral cultures, the Tzanck test, serum antibody titers, and fluorescent antibody testing.

Because herpetic whitlow is selflimited, treatment is directed toward symptomatic relief. Topical acyclovir may be beneficial in primary infections, and may reduce the duration of symptoms, which usually last 10 to 14 days. Patients endure less discomfort and resolution of symptoms is hastened if treatment is initiated within 48 hours of symptom onset. Early therapy may also reduce the duration of viral shedding, which typically lasts several days. Oral acyclovir may prevent recurrences if therapy is initiated during the prodrome phase.

Treat bacterial superinfection with antibiotics. Recurrences may occur in 20% to 50% of those affected. A felon involves the pulp space of the terminal phalanx and is usually tender, erythematous, and swollen. Vesicular lesions are not part of this disease process.

Herpetic whitlow is frequently confused with paronychia, which is often initially treated with surgical incision. This intervention may lead to delayed resolution, bacterial infection, or systemic spread and complications.

Cellulitis may be a complication of bacterial superinfection in a patient with herpetic whitlow. The history and physical examination should help delineate the cause of the underlying disease process.

References:

FOR MORE INFORMATION:

•Cockerell C. Diagnosis and treatment of cutaneous HSV infections.

West J Med.

1996; 164:518-520.

•Klotz RW. Herpetic whitlow: an occupational hazard.

AANA J.

1990;58:8-13.

•Kohl S. Herpes simplex virus. In: Feigin RD, Cherry JD, eds.

Textbook of Pediatric Infectious Diseases.

4th ed. Philadelphia: WB Saunders Co; 1998:1703-1731.

•Weisman E, Troncale JA: Herpetic whitlow: a case report.

J Fam Prac.

1991;33:516, 520.