Chapter 202: Paronychia

PATIENT STORY

A 41-year-old woman presented with a 3-day history of localized pain, redness, and tenderness of the lateral nail fold of the index finger. A small abscess had developed in the last 24 hours at the nail margin (Figure 202-1). After informed consent was given, a digital block was performed. This acute paronychia was treated with incision and drainage using a #11 scalpel (Figure 202-2). A significant amount of pus was drained. She soaked her finger four times daily as directed. Two days later the patient's finger was much better, and the culture grew out Staphylococcus aureus. Draining the abscess was sufficient treatment.

INTRODUCTION

Paronychia is a localized, superficial infection or abscess of the nail folds. It is one of the most common infections of the hand. Paronychia can be acute or chronic. Acute paronychia usually presents as an acutely painful abscess in the nail fold. Chronic paronychia is defined as being present for longer than 6 weeks' duration. It is a generalized red, tender swelling of the proximal or lateral nail folds. It is usually nonsuppurative and is more difficult to treat.

EPIDEMIOLOGY

Paronychia is the most common infection of the hand, representing 35% of all hand infections in the United States.¹

ETIOLOGY AND PATHOPHYSIOLOGY

• Paronychial infections develop when a disruption occurs between the seal of the nail fold and the nail plate or the skin of a nail fold is disrupted and allows a portal of entry for invading organisms.²

• Acute paronychia is most commonly caused by S. aureus, followed by streptococci and Pseudomonas (Figures 202-1, 202-2, 202-3, 202-4, 202-5).¹

• In digits heavily exposed to oral flora, acute paronychia may be caused by oral flora including aerobic bacteria (streptococci and Eikenella species) and anaerobic bacteria (Fusobacterium, Prevotella, Peptostreptococcus, and Porphyromonas species).³

• Chronic paronychia is an irritant or allergic reaction, secondary to contact, allergic, or hypersensitivity, or irritative causes^4,5 (Figures 202-6 and 202-7). Candida or Pseudomonas infection is sometimes a secondary phenomenon, or it may be a sensitizing agent.⁶

• Untreated persistent chronic paronychia may cause horizontal ridging, undulations, and other changes to the nail plate (see Figures 202-6 and 202-7).