Paronychia

Overview

Paronychia describes inflammation of the skin folds surrounding the fingernail, resulting in tender swelling which may be purulent. The most common fungal cause is Candida albicans. Common bacterial causes include Staphylococcus aureus, Pseudomonas aeruginosa, and Streptococcus species. Skin disruption around the nail allows the entry of organisms, resulting in infection and inflammation.

Chronic paronychia can occur if there is a disruption of the cuticles and nail folds.

Epidemiology

• Paronychial infections are one of the most common hand infections
• Incidence and prevalence are unknown, however, it is common in all age groups
• Paronychia is three times more common in women than in men

Risk Factors

• Nail trauma – such as excess trimming/manicuring etc.
• Concomitant nail problems – such as ingrown nails
• Water immersion – such as excess handwashing, dishwashing, gardening etc.
• Finger sucking and nail biting – especially in children, may lead to anaerobe infection
• Chemical irritant exposure
• Immunosuppression – including HIV and immunosuppressant drugs
• Diabetes mellitus
• Obesity
• Hyperhidrosis

Presentation

Overview

Paronychia can develop acutely and last for a few days (acute), or emerge gradually and last for >6 weeks (chronic). Features of acute paronychia include:

• Pain, swelling, and tenderness at the nail base and/or the nail folds
  • Usually, one finger is affected
  • There is often a history of nail trauma in the preceding week
• The nail folds may appear erythematous and swollen and may have visible pus
  • Fluctuance can suggest the presence of an abscess
  • A ‘floating nail’ can suggest a subungual abscess
• Digital pressure test – asking the person to oppose their thumb and affected finger (e.g. making the ‘OK’ sign if it is the index finger), causes blanching and demarcation of pus

Management

If there is no fluctuant pus or abscess and the infection is minor and localised:

• 1^st-line: apply moist heat to alleviate pain, localise infection, and accelerate pus drainage
• Consider topical antibiotics – such as fusidic acid cream

If fluctuant pus or an abscess is present:

• 1^st-line: incision and drainage:
  • May be done in primary care if the facilities are available, otherwise, the person should be referred to a hospital

If incision and drainage are not performed or were performed but there are features of extension, cellulitis, fever, or they have comorbidities (e.g. diabetes or immunosuppression), consider antibiotics:

• 1^st-line: flucloxacillin
• If allergic/inappropriate: clarithromycin or erythromycin if pregnant

Complications

Spread of infection – including spreading to the other nail fold, septic tenosynovitis, whitlow (spread of infection into deep spaces of hands), osteomyelitis, and septic arthritis.

Nail complications – including ridging, discolouration, thickening, and nail loss. 

Chronic paronychia – can occur if left untreated

Prognosis

• If treated promptly, the prognosis is very good and most cases resolve in a few days
• Complications are more common in immunocompromised people or people whose diagnoses have been missed