A paronychia is an infection of the soft tissue structures surrounding the proximal and lateral nail plate (perionychium).

The proximal nail fold (eponychium) and lateral nail folds (paronychium) normally provide a watertight seal around the border of the nail plate.

A paronychia develops with the introduction of microbes between the nail plate and the surrounding perionychium. This is often as a result of minor trauma that disrupts the seal between the nail plate and the nail folds. Commonly this is secondary to a hangnail, nail biting, or instrumentation of the perionychium following manicure.

Inflammation of the nail fold with erythema, pain, and swelling may progress to abscess formation.

If untreated, the abscess can spread and separate the nail plate from the nail bed or it can extend volarly into the pulp space of the finger tip.

Chronic paronychia occurs when repeated episodes of inflammation and drainage result in separation of the nail plate and the dorsal soft tissues of the nail fold. Chronic inflammation leads to thickening of the nail fold with resultant reduction in blood flow and thus susceptibility to recurrent episodes of infection (J Hand Surg Am 1991;16:314-317).

Paronychial infection is the most commonly seen hand infection.

Mixed bacterial infections are commonly seen, with Staphylococcus aureus the most frequently implicated organism.

Anaerobic infections are also seen, possibly due to contamination of the initial wound with the oral cavity (J Hand Surg 1993; 18:358-359 & Br J Surg 1981;68:420).

Chronic paronychia is often associated with more atypical bacteria, including Gram-negative organisms, mycobacterial
species, and fungal infections primarily Candida (J Hand Surg 1993; 18:358-359 & J Clin Microbiol 1988;26:950-953).

Initially there is erythema, swelling, and discomfort at the nail fold. This may then progress to abscess formation with fluctuance and visible pus at the nail fold.

Discomfort generally worsens as the abscess develops, resulting in a severe throbbing pain that can often disrupt sleep.

Duration of symptoms and any preceding treatment should be identified.

Factors that may lead to atypical microorganisms or resistance to standard treatment such as immunosuppression, diabetes, or chronicity of infection should be assessed.

Risk factors such as nail biting, frequent hand washing, and immersion of the hands in water, as well as tobacco smoking should be elicited.

Examination aims to identify the extent of the infection and the need for surgical drainage of any abscess.

Radiographs are not routinely indicated in uncomplicated cases of short clinical duration.

Patients who have not responded to initial treatment, who have had chronic symptoms, or those who present with significant abscess and swelling should have radiographs to exclude underlying osteomyelitis or foreign body.