eMedicine Specialties > Dermatology > Nails

Paronychia

Author: Steve Lee, MD, Physician in Plastic, Reconstructive, and Hand Surgery, Plastic Surgery, PLLC
Coauthor(s): Allison Vidimos, R PH, MD, Consulting Staff, Section of Micrographic Surgery (Mohs) and Oncology, Department of Dermatology, Cleveland Clinic Foundation; Yelena Bogdan, Stony Brook University Health Sciences Center School of Medicine (SUNY)
Contributor Information and Disclosures

Updated: Aug 11, 2009

Introduction

Background

Paronychia is a soft tissue infection around a fingernail. Paronychia occurs in 2 forms: acute and chronic. The etiology, infectious agent, and treatment are usually different for each form, and the 2 forms are often considered separate entities.

Pathophysiology

Mechanism

Paronychia, whether acute or chronic, results from a breakdown of the protective barrier between the nail and the nail fold. The entry of organisms into the moist nail crevice results in the bacterial or fungal (yeast or mold) colonization of the area.

Anatomy

The anatomy of the nail complex is shown in Media File 1. The nail is longitudinally flanked by 2 lateral folds or perionychium. Proximally, it is covered by the eponychium. Distal to the perionychium, the region immediately beneath the free edge of the nail is the hyponychium. The hyponychium serves as a tough physical barrier that resists bacterial infection.

The nail or nail plate lies immediately on top of the nail bed, which consists of 2 portions involved in the production, migration, and maintenance of the nail. The proximal portion, called the germinal matrix, contains active cells that are responsible for generating new nail. Damage to the germinal matrix results in malformed nails. The distal portion, the sterile matrix, adds thickness, bulk, and strength to the nail. The white crescent-shaped opacity at the proximal end of the nail is the lunula, which is the visible portion of the germinal matrix. The whiteness of the lunula is due to the poor vascularity of the germinal matrix. The nail arises from a mild proximal depression called the nail fold. The nail divides the nail fold into 2 components: the dorsal roof and the ventral floor, both of which contain germinal matrices. The skin overlying the nail fold is called the nail wall.

The nail bed receives its blood supply from the 2 terminal branches of the volar digital artery. A fine network in the proximal nail bed and in the skin proximal to the nail fold of the finger provides venous drainage. Lymphatic drainage follows a course similar to that of the venous network. The lymphatic network is dense in the nail bed, especially in the hyponychium. Innervation is derived from the trifurcation of the dorsal branch of the volar digital nerve. One branch goes to the nail fold, one to the pulp, and one to the distal tip of the finger.

Frequency

United States

Paronychia is the most commonly encountered hand infection, representing approximately 35% of all infections of the hand. Susceptible people include those whose occupations require them to have their hands in prolonged contact with water; such persons include bartenders, florists, bakers, and homemakers. In addition, individuals who are immunocompromised, such as those with HIV infection or those undergoing steroid therapy, are predisposed to paronychia.

Mortality/Morbidity

The motion of the affected finger may be limited in acute cases.

Race

No racial predilection is reported.

Sex

Paronychia is more common in women than in men, with a female-to-male ratio of 3:1.

Age

Paronychia may occur in patients of all ages.

Clinical

History

The patient's history is crucial in determining the possibility of more serious underlying systemic conditions that may predispose the patient to paronychia. These underlying conditions may include diabetes, obesity, hyperhidrosis, immunologic defects, polyendocrinopathy, and drug-induced immunosuppression.

• Acute paronychia
  • Patients with acute paronychia often present with a history of minor trauma to the fingertip or nail manipulation, intentional or not.
  • The presenting complaints are pain, tenderness, and swelling in one of the lateral folds of the nail.
• Chronic paronychia
  • Generally, patients complain of symptoms lasting 6 weeks or longer.
  • Inflammation, pain, and swelling may occur episodically, often after an exposure to water or a moist environment.

Physical

• Acute paronychia
  • The affected area often appears erythematous and swollen.
  • In more advanced cases, pus may collect under the skin of the lateral fold.
  • If untreated, the infection can extend into the eponychium, in which case, it is called eponychia.
  • Further extension of the infection can lead to the involvement of both lateral folds as it tracks under the nail sulcus; this progression is called a runaround infection.
  • In severe cases, the infection may track proximally under the skin of the finger and volarly to produce a concomitant felon. The fulminant purulence of the nail bed may generate enough pressure to lift the nail off the nail bed.
• Chronic paronychia
  • Swollen, erythematous, and tender nail folds without fluctuance are characteristic of chronic paronychia.
  • Eventually, the nail plates become thickened and discolored, with pronounced transverse ridges.
  • The cuticles and nail folds may separate from the nail plate, forming a space for the invasion of various microorganisms.

Causes

• Acute paronychia
  • Acute paronychia usually results from a traumatic event, however minor, that breaks down the physical barrier between the nail bed and the nail; this disruption allows the infiltration of infectious organisms.
  • Acute paronychia can result from seemingly innocuous conditions, such as hangnails, or from activities, such as nail biting, finger sucking, manicuring, or artificial nail placement.
  • Staphylococcus aureus is the most common infecting organism. Organisms, such as Streptococcus and Pseudomonas species, gram-negative bacteria, and anaerobic bacteria are other causative organisms.
  • Acute (and chronic) paronychia may also occur as a manifestation of other diseases, such as pemphigus vulgaris. Although instances of nail involvement in pemphigus vulgaris are rare, they can be severe, involving multiple digits and hemorrhage.
• Chronic paronychia
  • Chronic paronychia is primarily caused by the yeast fungus Candida albicans.
  • Other rare causes of chronic paronychia include bacterial, mycobacterial, or viral infection; metastatic cancer; subungual melanoma; and squamous cell carcinoma. Therefore, benign and malignant neoplasms should always be excluded when chronic paronychia does not respond to conventional treatment.
  • Chronic paronychia most often occurs in persons whose hands are repeatedly exposed to moist environments or in those who have prolonged and repeated contact with irritants such as mild acids, mild alkalis, or other chemicals. People who are most susceptible include housekeepers, dishwashers, bartenders, and swimmers.
• Other conditions associated with abnormalities of the nail fold that predispose individuals to chronic paronychia include psoriasis, mucocutaneous candidiasis, and drug toxicity from medications such as retinoids and protease inhibitors. Of particular interest is the antiretroviral drug indinavir, which induces retinoidlike effects and remains the most frequent cause of chronic paronychia in patients with HIV disease.

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