Paronychia

Background

• Inflammation/infection of the proximal or lateral nail folds
• Usually caused by direct or indirect minor trauma (e.g. nail-biting, manicures, hangnails, ingrown nail, dishwashing)
  • Trauma allows entry of bacteria
  • S. aureus is most common, although S. pyogenes, Pseudomonas pyocyanea, and Proteus vulgaris are also common
  • Can lead to distal phalanx osteomyelitis even if drained appropriately

Nailtip Anatomy

A. Nail plate; B. lunula; C. root; D. sinus; E. matrix; F. nail bed; G. hyponychium; H. free margin.

• The perinychium includes the nail, the nailbed, and the surrounding tissue.
• The paronychia is the lateral nail folds
• The hyponychium is the palmar surface skin distal to the nail.
• The lunula is that white semi-moon shaped proximal portion of the nail.
• The sterile matrix is deep to the nail, adheres to it and is distal to the lunule.
• The germinal portion is proximal to the matrix and is responsible for nail growth.

Clinical Features

Paronychia of middle digit

Paronychia as a secondary infection from a splinter.

• Rapid onset of erythema, edema, and pain of proximal or lateral nail folds
• Usually only affects one nail
• May see purulent drainage (expressed with pressure on nail)

Differential Diagnosis

Hand and finger infections

• Bed bugs
• Closed fist infection (Fight Bite)
• Hand cellulitis
• Hand deep space infection
• Hand-foot-and-mouth disease
• Herpetic whitlow
• Felon
• Flexor tenosynovitis
• Paronychia
• Scabies
• Sporotrichosis

Look-Alikes

• Digital mixoid cyst

Evaluation

• Clinical diagnosis, based on history of minor trauma and physical examination
• If unclear if wound is fluctuant:
  • Have patient apply pressure to distal aspect of affected digit
  • A larger than expected area of blanching, reflecting a collection of pus, may identify need for drainage

Management

Acute

More likely to be bacterial

• • Warm compresses, soaks, elevation
• Incision and drainage, if fluctuance or purulence is present
  • Consider soaking hand for preparation
  • Consider digital block
  • Incise area of greatest fluctuance
    • Incise parallel to nail (do NOT incise perpendicular to fluctulance)
    • Use iris scissors, flat tweezers, or #11 blade
• Antibiotics
  • Triple antibiotic ointment TID x 5-10 days (mild cases) ± topical steroid
  • PO Antibiotics (more severe or persistent cases)
    • Augmentin BID x 7 days OR
    • Clindamycin 150-450mg TID or QID x 7 days OR
    • TMP-SMX DS 1-2 tab PO BID x 7 days

Chronic

Multifactorial inflammation due to persistent irritation; may also have fungal component

• Mainstay of therapy is avoidance of irritant
• Consider topical antifungals vs Diflucan 150mg po qweek x 4-6 weeks
• Traditional treatments have been antifungals, but accumulating evidence suggests chronic paronychia is eczematous
  • Topical steroids to start in ED, with follow up for possible systemic steroids with PCP should be considered
  • Methylprednisolone aceponate cream 0.1%, over 3 weeks
  • OR betamethasone 17-valerate 0.1% for 3 weeks

Disposition

• Discharge

See Also

• Hand and finger infections