Chronic Paronychia

Chronic inflammation of the proximal and lateral nail folds lasting more than 6 weeks. It is mainly an irritant or allergic contact dermatitis of the nail fold, not a primary infection.

• Loss of the cuticle opens a space between the nail fold and nail plate. Water, soaps, food and microbes enter this space and keep the inflammation going. Candida species (and sometimes bacteria) colonise the space and perpetuate the process but are secondary.
• Common in people with prolonged wet work: bartenders, cleaners, dishwashers, nurses, food handlers, swimmers and homemakers. Also seen in diabetes, atopic dermatitis, and finger sucking in children.
• Drug causes: retinoids, EGFR inhibitors, indinavir and lamivudine, taxanes, and some antiretrovirals. Psoriasis, eczema and lichen planus of the nail fold can mimic it.
• Women are affected more than men, and several fingers (especially the thumb and middle finger) are often involved.

• Swollen, boggy, red, tender nail fold with absent cuticle. Pressing the fold may release a small amount of clear or cloudy fluid.
• The nail plate develops transverse ridges (Beau lines), a rough, brown, green or yellow discolouration and a wavy surface, because the matrix is irritated. The nail may be shed.
• Acute exacerbations show a painful red flare with pus, typically from S. aureus, which settles in 3 to 7 days.
• Healing is slow because nail regrowth takes 3 to 6 months for a fingernail.
• Differential diagnosis: acute paronychia, psoriasis, eczema, onychomycosis, squamous cell carcinoma of the nail fold (a single non-healing digit), amelanotic melanoma, herpetic whitlow, drug induced paronychia, nail lichen planus and metastatic disease.
• A single digit that fails to improve in 3 to 6 months despite correct treatment needs biopsy.
• Complications: permanent nail dystrophy, recurrent acute infection and secondary bacterial infection.

• Clinical, based on duration, loss of cuticle and the occupational history.
• Swab and culture any pus. Potassium hydroxide preparation and fungal culture can identify Candida or dermatophyte.
• Check HbA1c or fasting glucose and review medicines for causative drugs.
• Patch testing if contact allergy (latex, rubber chemicals, nail products) is suspected.
• Biopsy of the nail fold for a single persistent digit or an atypical appearance.

• Removing the cause is the core of treatment, and nothing else works if it is not done:
  • Keep hands dry. Avoid wet work, or wear cotton lined gloves under rubber or nitrile gloves for short periods only, removing them when they become damp.
  • Stop nail biting, manicuring, cuticle removal and artificial nails.
  • Apply a bland emollient to the nail folds after each hand wash.
• Topical anti-inflammatory therapy:
  • Mometasone furoate 0.1% or betamethasone valerate 0.1% ointment to the nail folds twice daily for 3 weeks, then once daily or on alternate days to taper. Limit continuous potent steroid use to 6 to 8 weeks because of skin atrophy.
  • Tacrolimus 0.1% ointment twice daily is a steroid sparing option for 4 to 12 weeks.
• Topical antimicrobial therapy where Candida is present: clotrimazole 1% or miconazole 2% lotion or cream twice daily for 4 to 6 weeks. Nystatin 100,000 units/g can be used.
• Oral antifungal therapy is used for failure of topical therapy or severe Candida involvement. Evidence is limited:
  • Itraconazole 200 mg orally daily for 1 week each month, for 3 to 4 months, or 100 mg daily for 4 to 6 weeks.
  • Fluconazole 150 mg orally once weekly for 4 to 12 weeks.
  • Avoid in pregnancy and check liver enzymes with prolonged courses.
• Acute bacterial flares: flucloxacillin 500 mg orally 6 hourly or cefalexin 500 mg orally 6 hourly for 5 to 7 days. Drain any abscess.
• Refractory disease after 3 to 6 months of correct therapy:
  • A short intralesional triamcinolone acetonide 5 to 10 mg/mL injection into the proximal nail fold, 0.1 mL per site, at 4 to 6 week intervals, with a maximum of about 3 injections.
  • Surgical eponychial marsupialisation or en bloc excision of the proximal nail fold, with healing by secondary intention over 6 to 12 weeks.
• Special groups:
  • Pregnancy: use emollients, topical steroid of moderate potency, topical clotrimazole and flucloxacillin or cefalexin for flares. Avoid oral azoles.
  • Children: treat finger sucking, use topical therapy and avoid oral azoles unless essential.
  • Diabetes and immunosuppression: control glucose and treat early.
• Follow up: review at 4 to 6 weeks, then every 3 months until nail growth normalises. Refer to dermatology for any single digit not improving by 3 months, and for biopsy if malignancy is suspected.