What is the Difference Between a Paronychia and a Felon?

Patient Presentation
A 7-year-old male came to clinic with a sore 4th finger on the left hand. He had a history of nail biting and had started to have pain the evening before. He denied any known trauma. His mother noticed some pus at the edge of the nail and after soaking his hand was able to move the cuticle back with expression of pus. In the morning the pus had reaccumulated and seemed to have spread with increased pain and swelling of the fingertip. His past medical history revealed him to be a healthy male who was fully vaccinated.

The pertinent physical exam showed a male holding his left hand to protect it. He could not tell if the pain was worse when he put his hand down. He had normal growth patterns and vital signs. His left 4th finger was very swollen. Laterally along the nailbed there was an obvious abscess from approximately the 7-11 o’clock position that was also extending to the volar area. There was erythema around the abscess. It was difficult to tell if this extended into the fingertip pulp because there was a great deal of edema. The patient complained of pain with any manipulation of the finger.

The diagnosis of a paronychia with abscess or extension to a felon was made. The resident was keen to treat the patient in clinic, but the patient was referred to the emergency room. “You are right about how this needs surgical treatment, but in our clinic we don’t have all the necessary ingredients. We treat minor problems such as a minor paronychia, but this is going to require proper pain control with at least a digital block. It may also need more extensive debridement because this may actually be a felon. Plus I’m not sure he can actually cooperate with us to do the procedure. We also do not have surgical colleagues to back us up if needed. This is an appropriate emergency room referral where they have the appropriate facilities, people and backup,” said the attending.

The patient’s clinical course in the emergency room showed that the patient was given light conscious sedation to help with his cooperation along with a digital block. The incision and drainage and debridement did not find extension into the pulp space, but the patient was to followup in the surgery clinic in 2 days time.

The hands are one of the most important parts of the body for interacting with the world. They are remarkably adapted having sensitive sensory receptors as well as feedback receptors for grasping, holding, and manipulating objects. Hands, especially with an opposable thumb, multiple joints within the hand, along with the wrist and elbow, allow the hand to move in multiple positions to manipulate the world. Hands also symbolize an emotional caring and sharing between individuals as hands are used to provide a true “human touch” in personal and social situations.

Due to their important interactions in the world, the hands are at risk for damage and infection. Most infections are superficial, acute and self-limited such as a cut, scratch or easily removed splinter. Osteomyelitis, deep space infection, septic arthritis, and tenosynovitis are emergent situations that need specialized treatment.

Fingertip infections are the most common hand infection. Again most of these are superficial such as a hangnail, but serious infections can occur. Paronychia is the most common. Felons are a different and less common but also important infection of the fingertip. Conditions which can look like paronychia and/or felon include herpetic whitlow, candida infection, reactive arthritis, and psoriasis in children. In adults other diseases such as cancer and gout occur. Hands are also where animal bites commonly occur. Cats cause more bites than other animals such as dogs. Below are some common infections associated with various species of bites or activities:

  • Cat – Pasteurela multocida, Bartonella henselea
  • Dogs – Staphylococcus sp., Streptococcus sp., Fusobacterium sp.
  • Sheep or goats – Parapox virus
  • Crustaceans and various livestock – Erysipolotrix rhusiopathiae
  • Gardening activities – Sporotrthrix schenckii (fungus)

Single or multiple infectious agents can be seen depending on the traumatic event (e.g. closed in a door, penetrating), situation (dirty area or clean), and potential animal species. Remember that human oral organisms are common causes of paronychia due to nail biting or people just putting their hands near/into their mouths during activities of daily living.

Learning Point
Paronychias are quite common and are usually caused by a breakdown of the seal between the nail fold and nail plate along the edge of the nail. This occurs often because of nail biting, hangnail manipulation, manicures, ingrown nails and other trauma. This is usually a polymocrobial infection with Staphylococcus aureus, Streptococcus sp.,Bacteroides, Enterococcus or Eikenella. Usually it is an acute infection but chronic infections (>6 weeks) can occur due to irritants or allergens. Clinically there is erythema, edema and localized pain at the lateral nail bed. It may feel boggy and tender. An abscess may also be present with purulent appearing fluid being trapped in the tissue adjacent to the nailbed. The Turkman test for abscess involves pressing lightly on the volar aspect of the digit. There will be a localized area of skin blanching around the nail if an abscess is present. The paronychia can extend under the nail bed and even around to the other side. Early stages without abscess formation are usually treated with oral antibiotics. Although soaking does not have clear evidence to recommend it, it is a common treatment used to keep the area clean and the cuticles softened to allow any accumulating fluid to drain. A localized abscess requires drainage. Depending on the extent, blunt dissection, sterile needle drainage, or more extensive incision and drainage may be necessary. Pain control with a digital block is often used and local pain control may include lidocaine. Epinephrine and/or finger tourniquets may be needed for more extensive debridement to help with blood control. Frequent dressing changes, post-procedure antibiotics and followup are important to make sure the infection has been mechanically cleared and is healing properly.

Felons are less common and are an infection in the fingertip pulp. Multiple septae that run from the bone to the skin providing support for the pulp but also create closed spaces where infections can try to hide. There is usually erythema and a great deal of edema which leads to very painful intense throbbing of the area which often increases with the hand in a dependent position. If the pressure increases there can be ischemia of the tissue due to the pus formation and edema. Felons occur more often on the first and second digits usually caused by penetrating trauma but patients may not identify the trauma commonly. They can occur due to paronychia extension. Felons require surgical treatment with appropriate incision, drainage and debridement. Because of the multiple septae, more extensive blunt dissection may be necessary. Because of patient age or the extent of the tissue involved, treatment in the operating room may be necessary but they are often treated in the surgical clinic or emergency room. As with paronychia, frequent dressing changes, post-procedure antibiotics and followup are important to make sure the infection has been mechanically cleared and is healing properly.

Questions for Further Discussion
1. How do you treat paronychias in your location?
2. What are indications for consultation with a hand surgeon?
3. How does compartment syndrome occur?
4. How common is tetanus in extremity injuries? A review can be found here

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Hand Injuries and Disorders

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Koshy JC, Bell B. Hand Infections. J Hand Surg Am. 2019;44(1):46-54. doi:10.1016/j.jhsa.2018.05.027

Barger J, Garg R, Wang F, Chen N. Fingertip Infections. Hand Clin. 2020;36(3):313-321. doi:10.1016/j.hcl.2020.03.004

Macneal P, Milroy C. Paronychia Drainage. In: StatPearls. StatPearls Publishing; 2021. Accessed September 28, 2021. http://www.ncbi.nlm.nih.gov/books/NBK559146/

Nardi NM, McDonald EJ, Schaefer TJ. Felon. In: StatPearls. StatPearls Publishing; 2021. Accessed September 28, 2021. http://www.ncbi.nlm.nih.gov/books/NBK430933/

Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa