A paronychia is inflammation of the soft tissue surrounding the nail plate, commonly caused by an infection or an abscess (Figure 132-1). It is the most common infection of the hand.1,2 A paronychia can be located on the fingers or the toes. It occurs in all age groups. It can cause significant pain and discomfort leading to a visit to the Emergency Department.
A paronychia initially presents with redness, swelling, and tenderness along the edges of the nail plate (Figure 132-1). This can progress to an abscess that requires drainage. An infection that extends to the overlying proximal cuticle is termed an eponychia. This chapter discusses the treatments which vary with the extent and the location of the infection.
ANATOMY AND PATHOPHYSIOLOGY
The dorsal aspect of the distal digit consists of the nail plate, the nail bed (i.e., matrix), and the perionychium (Figure 132-2). The nail bed is situated beneath the nail plate and is responsible for growth of the nail. The perionychium is the soft tissue surrounding the nail plate. It is composed of the eponychium proximal to the nail plate and the lateral nail folds.
The distal finger illustrating a paronychia and the surface anatomy.
A paronychia is usually the result of minor trauma to the seal formed by the nail plate and nail fold.3 This may occur from tight-fitting apparel (e.g., gloves, pantyhose, and shoes), aggressive manicures, the use of artificial nails, hangnails or ingrown nails, foreign bodies, or nail biting.3,4 The disruption of this seal allows bacteria to enter causing a localized cellulitis that may progress to abscess formation in the potential space between the nail plate and nail fold (Figures 132-1 and 132-2).1,5 A paronychia can grow and spread under the nail plate causing a subungual abscess. The infection may advance to the volar soft tissues and deep structures resulting in a felon, osteomyelitis, or tenosynovitis.6
Most paronychia are polymicrobial. They often contain a mixture of aerobic and anaerobic organisms.7,8 The most common organism to cause a paronychia is Staphylococcus aureus.9 Paronychia are often caused by anaerobes secondary to finger sucking or nail biting in children and nail biters.10 Gram-negative organisms should be considered in immunocompromised hosts. The etiology of a chronic paronychia is complex and likely multifactorial. Patients are often colonized with Candida albicans but the infection is not likely the cause.11 Chronic paronychia refractory to steroid and pathogen-directed therapies must be considered as result of a neoplasm (e.g., subungual ...