August 2008

A 6-year-old black girl presented with pain and swelling of the tip of her left index finger.

The pain and swelling began after the patient had been chewing on her fingers. She was diagnosed with cellulitis of the pulp of the finger. It was drained and the patient was discharged home on a seven-day course of trimethoprim/sulfamethoxazole. Subsequently, the aspirate cultures grew methicillin-resistant Staphylococcus aureus.

The wound showed significant improvement within a few days.

After two months, the patient presented with pain and swelling of the same finger without any systemic symptoms. Her physical exam was within normal limits except for an ulcer in her distal fingertip of her left index finger, surrounded by an area of erythema restricted to the area above her distal interphalangeal joint. Lab evaluation included complete blood count, blood cultures and C-reactive protein, and all results were within normal limits. Plain X-ray of the hand revealed bony destruction of the distal phalynx consistent with osteomyelitis (figure 1), which was confirmed by MRI.

A punch biopsy of the fingertip revealed findings consistent with chronic osteomyelitis. The distal fingertip was eventually amputated and the patient was treated with intravenous vancomycin. She was discharged on a 10-day course of vancomycin. Follow-up inflammatory markers (erythrocyte sedimentation rate and CRP) were within normal limits. Subsequently, when the patient developed an extensive rash vancomycin was discontinued and the rash resolved with a short course of prednisone. The patient was referred for plastic surgery and received physical therapy with significant progress.

What’s your diagnosis?

Answer

Nail-biting, also known as onychophagia, is a common habit of children as well as adults. The incidence is estimated at 28% to 33% in children aged between 7 and 10 years and 45% among adolescents. Complications from nail-biting can range from simple damage to the cuticle to more drastic osteomyelitis, as in this patient. In one study, more than 80% of patients requiring surgical treatment for paronychia were found to be either nail-biters or nail-pickers. Despite these data, there seems to be a lack of literature regarding nail-biting, which could lead to under-recognition and a lack of early intervention.

Cases of nail-biting leading to osteomyelitis have been reported in adults as well as in children. Nonhematogenous osteomyelitis of the finger can occur with or without systemic signs of inflammation such as fever, leukocytosis and elevation of ESR. Osteomyelitis also can occur in the absence of any periungual inflammation.

Chronic nail-biting also seems to have an effect on oral pathogens. One study showed a statistically significant increase in the prevalence of Enterobacteriaceae in the oral cavities of children with nail-biting habits compared with children with no oral habit. Therefore, the chronic nail-biters have a higher contamination risk than the patients with no oral habit.

Recognition and elimination of an oral habit such as nail-biting is of utmost importance to avoid the potential complications. With increasing cases of MRSA colonization, frequent hand-washing should be encouraged. Behavioral modifications, such as alternate activities involving the use of hands and positive reinforcement, are some suggested intervention methods. Because nail-biting also can be precipitated by rough nail edges and cuticles, nail care with manicure seems to be a logical preventive measure for nail-biting. High index of suspicion for underlying osteomyelitis should be considered in cases of pulp infection secondary to nail-biting.

For more information:

• Meera Varman, MD, is an Assistant Professor in the Department of Pediatric Infectious Diseases at Creighton University in Omaha, Neb.
• Baran R, Dawber RPR eds. Diseases of the Nails and Their Management. Oxford: Blackwell Scientific Publications;1984:377-379.
• Baydas B, Uslu H, Yavuz I, et al. Effect of a chronic nail-biting habit on the oral carriage of Enterobacteriaceae. Oral Microbiol Immunol. 2007:22:1-4.
• Leung AK, Robson WL. Nailbiting. Clin Pediatr. 1990;29:690-692.
• Sagerman SD, Lourie GM. Eikenella osteomyelitis in a chronic nail biter: a case report. J Hand Surg. 1995:71-72.
• Tosti A, Peluso AM, Bardazzi F, et al. Phalangeal osteomyelitis due to nail biting. Acta Derm Venereol. 1994;74:206-207.
• Waldman BA, Frieden IJ. Osteomyelitis caused by nailbiting. Pediatr Dermatol. 1990;7:189-190.