Skin and Soft Tissue
Core concepts
Focus on distinguishing cellulitis, abscess, necrotizing soft tissue infection, and benign lesions requiring excision. Understand when incision and drainage is the definitive treatment (abscess) versus when antibiotics alone suffice (uncomplicated cellulitis). Recognize the red flags for necrotizing fasciitis: pain out of proportion, rapid progression, systemic toxicity, crepitus, and skin necrosis or bullae.
Traps
- Abscess vs. cellulitis: a fluctuant collection needs drainage; antibiotics alone often fail. Questions test whether you choose drainage.
- Necrotizing infection: early findings can mimic cellulitis; the key is disproportionate pain and rapid deterioration. Surgical exploration is both diagnostic and therapeutic-don't delay for imaging.
- Suspicious skin lesions: apply ABCDE criteria for melanoma; any changing or atypical lesion warrants biopsy.
- Bite wounds: consider specific organisms and tetanus/rabies prophylaxis; human and animal bites need careful irrigation and selective antibiotics.
Rule of thumb
If a soft tissue infection is rapidly progressive with systemic toxicity or pain out of proportion, take the patient to the operating room for exploration rather than waiting for imaging.
Worked example
A diabetic patient with a rapidly spreading leg infection, severe pain, and crepitus: suspect necrotizing fasciitis. Immediate broad-spectrum antibiotics plus urgent surgical debridement; imaging should not delay operation.