Dermatology · Infectious Skin Conditions
The facts most likely to be tested
Acute paronychia is a superficial infection of the lateral nail fold typically caused by Staphylococcus aureus.
The primary clinical presentation is erythema, edema, and tenderness localized to the periungual tissue.
Initial management for early-stage paronychia without an abscess involves warm compresses and topical antibiotics.
The presence of a fluctuant collection or purulence necessitates incision and drainage as the definitive treatment.
Chronic paronychia is often associated with irritant contact dermatitis or repeated exposure to moisture rather than a primary bacterial infection.
Herpetic whitlow is a viral mimic of paronychia caused by HSV-1 or HSV-2 and is characterized by painful vesicles on an erythematous base.
Incision and drainage is contraindicated in herpetic whitlow because it can lead to secondary bacterial superinfection or viral dissemination.
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A 28-year-old nail technician presents with a 3-day history of increasing pain and swelling around the cuticle of her right index finger. Physical examination reveals erythema, edema, and tenderness along the lateral nail fold. A small fluctuant collection of purulent material is noted at the base of the nail. She has no history of trauma or systemic symptoms.
What is the most appropriate next step in management?
Incision and drainage
The presence of a fluctuant abscess indicates that conservative management with warm soaks is insufficient, and surgical drainage is required to resolve the infection.
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Etiology / Epidemiology
Common in nail biters and manicurists due to disruption of the protective nail seal.
Clinical Manifestations
Localized erythema, edema, and tenderness at the nail fold; felon if pulp space involved.
Diagnosis
Primarily a clinical diagnosis; culture only if purulent drainage is present.
Treatment
Warm soaks and cephalexin for bacterial infection; incision and drainage for abscess.
Prognosis
Excellent with drainage; monitor for osteomyelitis if symptoms persist > 48 hours.
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Epidemiology & Etiology
Occurs via inoculation of bacteria into the periungual tissue. Frequent in patients with onychophagia (nail biting) or those performing repetitive hand immersion. Common pathogens include Staphylococcus aureus and Streptococcus species.
Pertinent Anatomy
The eponychium (cuticle) acts as a physical barrier protecting the nail matrix. Disruption of this seal allows bacterial entry into the lateral or proximal nail folds.
Pathophysiology
Initial inflammation leads to localized cellulitis. If untreated, the infection tracks into the paronychial space, forming an abscess. Progression into the deep volar pulp space results in a felon.
Clinical Manifestations
Patients present with painful, erythematous swelling of the nail fold. Purulent drainage may be visible beneath the cuticle. Red flags include crepitus, deep space involvement, or lymphangitis indicating progression to a felon or deep infection.
Diagnosis
Diagnosis is clinical. Imaging is reserved for suspected osteomyelitis or deep space abscess. Plain radiographs are the gold standard if bone involvement is suspected.
Treatment
Mild cases require warm soaks and topical antibiotics. For abscess, incision and drainage with a #11 blade is the definitive treatment. Systemic cephalexin is indicated for significant cellulitis. Do not use topical steroids as they exacerbate bacterial growth.
Prognosis
Most cases resolve within 48-72 hours post-drainage. Failure to improve suggests osteomyelitis or retained foreign body requiring surgical consultation.
Differential Diagnosis
Felon: involves the deep volar pulp space
Herpetic whitlow: vesicles present, not purulent
Onychomycosis: chronic, painless nail discoloration
Squamous cell carcinoma: chronic, non-healing ulceration
Contact dermatitis: bilateral, pruritic, non-purulent