Pathophysiology

The infecting pathogen is herpes simplex virus (HSV-1 or HSV-2). Transmission may occur from a primary herpetic lesion or infected body fluids. The virus remains dormant in the nerve ganglia; secondary eruptions may be related to stress, certain foods, sun exposure, and unknown precipitants.

Clinical Presentation

Herpetiform vesicles or blisters erupt on the distal phalanx, sometimes after a short prodromal period of flulike symptoms (particularly in the primary infection) and throbbing, tingling, numbness, or pruritus in the area of the eruption. Painful vesicles can be singular or coalescent, resemble a group of warts or a bacterial infection, and persist for 8 to 12 days; lesions then begin to dry, forming crusted fissures.³ The course of the eruptions can persist for 21 days until resolution; healing may take longer in areas that remain moist. In addition to the vesicles, the fingertip may be edematous, erythematous streaking may be evident on the forearm, and the axillary lymph nodes may become enlarged.

Physical Examination

The nails should be inspected for shape, configuration, texture, and herpetiform vesicles. Axillary and epitrochlear nodes should be examined for lymphadenopathy. Examination for genital herpes should be considered if there are genital symptoms.

Diagnostics

Diagnosis is typically established based on history and physical examination findings. If warranted, viral culture of vesicular fluid, Tzanck smear, or serum titer may be used to confirm the diagnosis.² If second­ary bacterial infection is sus­­pected, bacterial culture may be indicated.

Differential Diagnosis

See differential diagnosis box.

Use of incision and drainage (I&D) is avoided because it may lead to superinfection² or longer duration of healing.¹ Cool compresses can be used to decrease erythema and to debride crusts, thus promoting healing.³ The area should be covered with gauze to prevent transmission. The area is kept dry because moisture may prolong healing and promote superinfection. Analgesics are used at doses appropriate for the patient’s age and medical history. Oral antivirals (acyclovir, famciclovir, valacyclovir) may be considered for severe cases, management of recurrences, during the prodromal period, and in patients with acquired immunodeficiency syndrome (AIDS).² Creatinine clearance should be checked and the dose adjusted according to the creatinine clearance values if they are abnormal. L-Lysine is ineffective.³

Complications

Secondary bacterial infection in conjunction with the viral syndrome is possible. Transmission to others during viral shedding is possible.

Indications for Referral or Hospitalization

Physician referral is necessary if the virus is recalcitrant to treatment after 3 weeks. Hospitalization should not be required.

Lifespan Considerations

Herpetic whitlow is generally more common in young children and young adults. Atypical presentations and more severe infection can occur in immunocompromised individuals.

Education and Health Promotion

Patients require education about the risk of infecting others and medication administration. If used in recurrences, antivirals should be administered within 48 hours of the first prodromal signs. Patients should be advised to keep their infected digits away from the mouth and eyes to prevent inoculation of these surfaces with the virus. If patients work in occupations in which they could infect other persons (e.g., health care providers, dental providers, manicurists), they should be advised to wear gloves when working. The provider should carefully explain signs and symptoms of infection and encourage the patient to call if complications develop.

Pathophysiology

There are numerous possible causative organisms for acute paronychial infections. Some organisms include Pseudomonas, Proteus, Streptococcus, Staphylococcus, Candida albicans, and HSV.^4,5 A paronychial infection results when periungual tissue is inoculated by trauma, inert vehicles such as water, or soluble chemicals. The resulting infection follows the nail margin or the infection penetrates under the nail.

If paronychial inflammation is present for longer than 6 weeks, the condition is considered a chronic paronychia. Chronic paronychia is primarily an inflammatory disorder, but C. albicans is also often present. It is most commonly present in workers with frequent exposure to environmental irritants (such as cooks, dishwashers, and nurses).⁴

Medications can cause chronic paronychia, increasing the risk for infection. Retinoids and protease inhibitors (e.g., lamivudine [Epivir], darunavir [Prezista], and fosamprenavir [Lexiva]) affect nail fold integrity, setting the stage for a paronychia.^6,7 An antiretroviral, indinavir (Crixivan), is associated with paronychias as a result of interference with retinoid metabolism.⁸ Chemotherapeutic selective inhibition of the epidermal growth factor receptor (EGFR; e.g., cetuximab) is increasingly used to treat solid organ malignant neoplasms in patients whose standard chemotherapeutic regimens have failed. Tenderness, swelling, and pain in both fingers and toes occur after 2 weeks to months of therapy. Anatomic predisposition may increase risk in the development of paronychias.⁹

Clinical Presentation and Physical Examination

Symptoms are usually localized to one finger, and patients report throbbing pain of the nail fold, nail, and even adjacent portions of the finger. The affected nail may display distal onycholysis, discoloration, distortion, and ridging; the affected nail folds have erythema and edema. When the examiner applies force to the affected area, there can be a release of purulent, often foul-smelling discharge.⁵ Pyogenic granuloma–like lesions and granulation tissue are seen in the nail sulci in paronychias associated with indinavir and anti-EGFR agents.⁸

Diagnostics

Skin scrapings can be combined with potassium hydroxide (KOH) preparation on a glass slide and viewed under a microscope. Pseudohyphae and spores indicate candidal infection. Any exudate from the nail can be cultured to determine the pathogen and to guide treatment.