Differential Diagnosis for a Simple Bite to the Hand
For a bite wound to the hand, the primary differential diagnosis focuses on distinguishing between infectious complications rather than alternative non-infectious diagnoses, as the traumatic etiology is already established.
Infectious Complications to Consider
Primary Infection Types
- Cellulitis - superficial spreading infection involving epidermis and dermis 1, 2
- Abscess formation - localized collection of purulent material in subcutaneous tissue 3, 4
- Pyogenic flexor tenosynovitis - bacterial infection of the flexor tendon sheath, particularly concerning with penetrating injuries 3, 4
- Septic arthritis - joint space infection, especially high risk with clenched-fist injuries that penetrate the metacarpophalangeal joint 1, 2, 5
- Osteomyelitis - bone infection requiring 6 weeks of antibiotic therapy 1, 2
- Deep space infection - involvement of deep fascial planes, bursae, or anatomic compartments 6, 4
Specific Bite-Related Considerations
Human Bites:
- Polymicrobial infection with Streptococcus viridans (80% of cases), Staphylococcus aureus (40%), Eikenella corrodens (30%), and anaerobes (60%) 7, 5
- Clenched-fist "fight bite" injuries with extensor tendon, joint capsule, and bone involvement 1, 3
- Viral transmission including herpes simplex, hepatitis B/C, and HIV 1, 7
Animal Bites:
- Pasteurella multocida and Pasteurella canis from cat and dog bites 5
Non-Infectious Mimics (Secondary Considerations)
While the bite wound itself is traumatic, clinicians should briefly consider:
- Drug eruption - if systemic symptoms or rash extends beyond bite site 1
- Herpetic whitlow - herpes simplex virus infection that can mimic bacterial infection but requires antiviral rather than antibiotic therapy 3, 4
Critical Diagnostic Pitfall
The most important differential is distinguishing primary cellulitis from secondary cellulitis due to underlying deep infection (abscess, tenosynovitis, necrotizing fasciitis, or osteomyelitis), as misdiagnosis leads to inadequate treatment with antibiotics alone when surgical intervention is required 8.