Hand Cellulitis

Hand cellulitis is bacterial infection of the dermis and subcutaneous tissue of the hand and fingers, mostly by Staphylococcus aureus and streptococci. Because of the compact anatomy of the hand, infection can spread rapidly to tendon sheaths, deep spaces and joints and may cause permanent loss of function.

• Entry: wounds, bites (human, animal), paronychia, felon (pulp space infection), injection, puncture, burns.
• Risk factors: diabetes, injection drug use, immunosuppression, manual work, wet work, nail biting.

Painful, red, swollen, warm hand or finger, with limited movement and fever; lymphangitic streaking up the forearm and tender epitrochlear or axillary nodes.

• Flexor tenosynovitis (Kanavel signs): finger held in flexion, fusiform swelling, tenderness along the flexor sheath, pain on passive extension.
• Deep palmar space abscess: loss of palmar concavity, severe palmar pain; web space abscess: abducted fingers.
• Differential diagnosis: herpetic whitlow, felon, paronychia, septic arthritis, gout, pseudogout, contact dermatitis, necrotising fasciitis, bite wound infection, extravasation injury, cellulitis from fungal origin.
• Complications: tenosynovitis, deep space abscess, septic arthritis, osteomyelitis, finger necrosis, stiffness, loss of function, necrotising fasciitis, sepsis, amputation.

Clinical, with imaging for deep infection.

• Radiograph of the hand for foreign body, gas, osteomyelitis; ultrasound for abscess or sheath fluid; MRI if deep infection is suspected.
• Wound swab and blood cultures; full blood count, CRP, glucose; HIV test as indicated.

Elevation, splinting and antibiotics, with surgical drainage of any collection.

• Supportive: elevate the hand above heart level, splint in a safe position (wrist neutral, metacarpophalangeal joints flexed 70 to 90 degrees, interphalangeal joints extended), remove rings, analgesia (paracetamol 1 g, ibuprofen 400 mg), tetanus toxoid 0.5 mL IM if immunisation is out of date, mark the erythema.
• Pharmacological: mild: flucloxacillin 500 mg to 1 g four times daily for 7 days (cefalexin 500 mg four times daily; clindamycin 300 to 450 mg three times daily if penicillin allergic). Moderate or severe, bite related or diabetic: amoxicillin clavulanate 1.2 g IV every 8 hours, or ceftriaxone 2 g IV daily with metronidazole 500 mg IV every 8 hours; add vancomycin 15 to 20 mg/kg IV every 12 hours for MRSA. Duration 7 to 14 days (2 to 6 weeks for bone or joint involvement). Herpetic whitlow (do not drain): valaciclovir 1 g twice daily for 7 days.
• Procedures: urgent incision and drainage of felon, deep space abscess and flexor tenosynovitis with irrigation; surgical washout of joint; debridement of necrotic tissue; amputation for gangrene.
• Special groups: pregnancy, flucloxacillin or cefalexin; children, flucloxacillin 12.5 to 25 mg/kg four times daily and early surgery; diabetes, admit and give IV antibiotics early; injection drug users, screen for blood borne viruses and endocarditis.
• Red flags: Kanavel signs, severe pain with passive extension, rapid spread, fever, crepitus, skin necrosis, loss of sensation, bite injury, no improvement within 24 to 48 hours.
• Follow-up: review at 24 hours; early hand therapy after resolution; refer to hand surgery for any deep infection.