May 2001

A 7-year-old boy came to the clinic for evaluation of a sore finger. He first noticed the pain about 2 days earlier. There is no history of trauma, fever or any other systemic signs or symptoms. He did notice a greenish discoloration next to the nail. On the first visit, he was diagnosed with a paronychia and treated with cefadroxil (Duricef, Bristol-Myers Squibb) at 500 mg twice daily and warm Epsom salts soaks, and told to return the next day if not better. He came back as directed with his finger somewhat worse. He is otherwise healthy and has not had any other complaints. Examination reveals the left index finger shown in figures 1 and 2.

The abscess was drained (figure 3) and the pus sent for Gram’s stain and culture. Gram’s stain revealed moderate white blood cells and a large number of gram-positive cocci and a large number of gram-negative rods.

What’s Your Diagnosis?

1. Blistering distal dactylitis (group A streptococcus)
2. Green nail syndrome
3. Herpetic whitlow
4. Paronychia due to mixed infection

Answer

This turned out to be a simple paronychia. The culture only grew a moderate amount of Haemophilus species, not influenzae. However, based on the Gram’s stain, it is likely that staph was also in the mix, but not viable on culture due to the previous treatment. Drainage was curative. The unusual feature of this case was the color of the skin overlying the abscess, with its greenish hue. I have no explanation for this except that the organism recovered is not among the usual causes.

Characteristics and treatments

The green nail syndrome is caused by a Pseudomonas aeruginosa paronychia and results in a discoloration of the nail plate. It is usually seen in adults as an occupational hazard from having their hands in prolonged contact with water. This discoloration results from the spread of a pigment under the nail called pyocyanin from the paronychia. The treatment is drainage of the paronychia, however, the green stain will remain (figure 4) and will eventually resolve as the nail grows out.

Blistering distal dactylitis is just what the name describes. It is almost always due to group A streptococcus (Streptococcus pyogenes). Rarely, Staphylococcus aureus may be the cause alone or in combination with strep. It is not like a typical paronychia, with the infection adjacent to the nail, but rather a blister-like lesion usually over the anterior tip or pad of the finger. It has been known to occur on toes, or in unusual locations on the finger (figure 5), but the vast majority appear like that shown in figure 6. Treatment is an anti-strep antibiotic and drainage.

The herpetic whitlow is essentially an infection of the finger caused by herpes simplex virus. It can appear like a paronychia or blistering distal dactylitis, depending on the extent and location of the lesion(s). These lesions are usually discrete vesicles, but when confluent, they can appear like a larger blister or abscess (figure 7).

Acknowledgements: Thanks go to Alicia Leffel, MD, pediatrician at the Scott & White Pediatric Clinic in Waco, Texas, for her help with this case. Also, I would like to again thank Jim Bass, MD, of Honolulu, Hawaii, for contributing figures 4, 6 and 7. Without his extensive collection of clinical photographs and ever-available words of wisdom, this column would be much less interesting or practical, and I could not have written it for all these years.

For Your Information:

• James H. Brien, DO, Pediatric Infectious Disease, Scott and White's Children's Health Center and Texas A&M University, College of Medicine, Temple, Texas. E-mail: jhbriend@aol.com