Description

• Inflammation of the lateral and posterior folds of skin surrounding the fingernail or toenail:
  • Acute: Characterized by pain, erythema, and swelling; usually a bacterial infection, often appearing 2–5 days after trauma (1)
  • Chronic: Characterized by swelling, tenderness, cuticle loss/separation, and nail dystrophy (1)
  • May be considered work-related among bartenders, waitresses, nurses, and others who often wet their hands (1)
• System(s) affected: Skin/Exocrine
• Synonym(s): Eponychia; Perionychia

Pediatric Considerations
Thumb/Finger-sucking is a risk factor (anaerobes and Escherichia coli may be present).

Epidemiology

• Common in the US
• Predominant age: All ages
• Predominant sex: Female > Male (3:1)

Risk Factors

• Acute: Trauma to skin surrounding nail, ingrown nails, manicured/sculptured nails, diabetes mellitus (DM), nail biting, and thumbsucking
• Chronic: Frequent immersion of hands in water (e.g., cooks, chefs, bartenders, housekeepers, swimmers), DM, immunosuppression (reported association with antiretroviral therapy for HIV and with use of epidermal growth factor inhibitors)

General Prevention

• Acute: Avoid nail biting; prevent thumbsucking.
• Chronic: Avoid allergens; keep fingers/hands dry; wear rubber gloves with a cotton liner.
• Good diabetic control

Pathophysiology

• A paronychial infection usually starts in the lateral nail fold.
• Occasionally, the infection includes the complete margin of skin around the nail plate, which results from mechanical separation of the nail plate from the perionychium.
• Early in the course of this disease process (<24 hours), cellulitis alone may be present. An abscess can form if the infection does not resolve quickly.
• Chronic infections most likely represent eczematous reaction with secondary infection and multifocal etiology.

Etiology

• Acute: Staphylococcus aureus and Streptococcus pyogenes; less frequently, Pseudomonas pyocyanea and Proteus vulgaris. In digits exposed to oral flora, also consider Eikenella corrodens, Fusobacterium, and Peptostreptococcus.
• Chronic: Eczematous reaction with secondary Candida albicans (~95%); less frequently, dermatophytes and, occasionally, molds (Scytalidium, Fusarium)

Commonly Associated Conditions

• DM
• Eczema or atopic dermatitis
• Certain medications: Cetuximab, paclitaxel, antiretroviral therapy (especially protease inhibitors and lamivudine, with toes more commonly involved)
• Immunosuppression
• If multiple, consider pemphigus vulgaris (rare)