Inflammation of the proximal or lateral nail fold; acute is usually bacterial, chronic is irritant/Candida-driven.
Also known as: paronychia, nail fold infection, whitlow
Overview
Inflammation of the periungual tissues. Acute paronychia (lasting <6 weeks) is typically a bacterial infection of the lateral or proximal nail fold following minor trauma. Chronic paronychia (lasting >6 weeks) is a multifactorial dermatitis of the nail folds driven by prolonged moisture exposure, irritant contact, and secondary colonization by Candida albicans and bacteria.
Epidemiology
Common across all age groups. Acute paronychia is one of the most frequent hand infections seen in primary care and urgent care. Chronic paronychia is an occupational disease of those with persistent wet work — bartenders, dishwashers, healthcare workers, swimmers, mothers of infants, and patients with hand eczema or diabetes.
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Question 1DermatologyEasy
A 29-year-old woman presents with 2 days of throbbing pain and swelling along the side of her right index fingernail. She reports pulling off a hangnail earlier in the week. On exam there is erythema, edema, and a tender, fluctuant area of the lateral nail fold, and gentle pressure expresses a small amount of pus. There are no grouped vesicles, and the volar fingertip pulp is soft and nontender. The remaining digits appear normal. Which of the following is the most likely diagnosis?
AAcute bacterial paronychia
BFelon of the fingertip pulp
CEczema of the nail folds
DHerpetic whitlow infection
Reveal answer & full explanation
Correct answer: A — Acute bacterial paronychia
AAcute bacterial paronychia✓
BFelon of the fingertip pulp
CEczema of the nail folds
DHerpetic whitlow infection
Why Acute bacterial paronychia is correct
Acute paronychia is a bacterial infection of the lateral or proximal nail fold (most often Staphylococcus aureus, including MRSA) that follows minor trauma such as a hangnail, nail biting, or a manicure.
The classic finding is the rapid onset (24-48 hours) of throbbing pain, erythema, and a tender, fluctuant single-digit nail fold abscess that expresses pus on pressure, exactly this presentation.
Management is incision and drainage; adequate drainage is the cure, and oral antibiotics are reserved for surrounding cellulitis, immunocompromise, or diabetes.
Why the others are wrong
Herpetic whitlow infection: HSV inoculation of a digit produces grouped clear or cloudy vesicles with preceding tingling; the fluid is not true pus, and it must NOT be incised. The absence of vesicles and the presence of frank pus argue against it.
Felon of the fingertip pulp: a deep, closed-space infection of the volar fingertip pulp causing tense, severe throbbing swelling of the pad; here the pulp is soft and nontender and the process is limited to the nail fold.
Eczema of the nail folds: a chronic dermatitis with erythema and scaling of the periungual skin without purulence, typically part of hand eczema; it does not produce an acute fluctuant abscess with pus over 2 days.
Question 2DermatologyMedium
A 44-year-old bartender presents with a 3-month history of tender, swollen nail folds on several fingers of her dominant hand. She washes glassware and immerses her hands in water for most of her shift. On exam, the proximal nail folds are bolstered and erythematous, the cuticles are absent, and there is transverse ridging of several nail plates. There is no fluctuance and no expressible pus. A KOH preparation shows occasional Candida. Which of the following best explains the findings?
AA cuticle breach lets Staphylococcus aureus enter and form a localized nail fold abscess
BMechanical impingement of the nail plate into the lateral fold drives foreign-body inflammation
CViral inoculation of the nail fold seeds grouped intraepidermal vesicles in the periungual skin
DRepeated moisture breaks down the cuticle seal, exposing the matrix to irritants and microbes
Reveal answer & full explanation
Correct answer: D — Repeated moisture breaks down the cuticle seal, exposing the matrix to irritants and microbes
AA cuticle breach lets Staphylococcus aureus enter and form a localized nail fold abscess
BMechanical impingement of the nail plate into the lateral fold drives foreign-body inflammation
CViral inoculation of the nail fold seeds grouped intraepidermal vesicles in the periungual skin
DRepeated moisture breaks down the cuticle seal, exposing the matrix to irritants and microbes✓
Why Repeated moisture breaks down the cuticle seal, exposing the matrix to irritants and microbes is correct
Chronic paronychia (inflammation lasting more than 6 weeks) is fundamentally an irritant dermatitis of the nail folds, not a primary infection.
Prolonged water immersion and irritant exposure destroy the cuticle (the eponychium-nail plate seal); loss of this barrier lets irritants and microbes reach the matrix, producing chronic inflammation, bolstered folds, and Beau lines/ridging.
Candida and bacteria are secondary colonizers that amplify inflammation but do not initiate the disease, which is why topical high-potency corticosteroids, not antifungals, are first-line. Loss of the cuticle is the hallmark finding.
The wet-work occupation, multiple dominant-hand digits, absent cuticles, ridging, and absence of pus all point to the chronic dermatitis mechanism.
Why the others are wrong
A cuticle breach lets Staphylococcus aureus enter and form a localized nail fold abscess: this is the mechanism of acute paronychia, which presents over 24-48 hours as a fluctuant, single-digit abscess with expressible pus, not a 3-month multi-digit process without fluctuance.
Viral inoculation of the nail fold seeds grouped intraepidermal vesicles: this describes herpetic whitlow (HSV), which causes painful grouped clear/cloudy vesicles on a single digit; there are no vesicles here, and the chronic wet-work pattern does not fit.
Mechanical impingement of the nail plate into the lateral fold drives foreign-body inflammation: this is the mechanism of an ingrown toenail (onychocryptosis), a localized mechanical problem of the great toe, not a multi-digit fingernail dermatitis.
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Acute paronychia: a breach of the cuticle allows bacterial entry — Staphylococcus aureus (including MRSA) most common; Streptococcus, anaerobes (especially with oral contact), and Pseudomonas in immersion-related cases. Chronic paronychia: repeated moisture damages the cuticle, separating it from the nail plate and exposing the matrix to irritants and microbes; Candida colonization and bacterial overgrowth amplify the inflammation, but the disease is primarily a dermatitis, not an infection.
Clinical presentation
Symptoms
Acute: rapid onset of throbbing pain, redness, and swelling of one nail fold, often within 24-48 hours of minor trauma
Chronic: persistent intermittent tenderness, recurrent episodes affecting multiple digits, often involving the dominant hand or nails exposed to water
Drainage of purulent material with pressure on the fold in acute disease
Signs / physical exam
Acute: erythema, edema, fluctuance of the proximal or lateral nail fold; visible abscess with point tenderness; possible extension under the nail plate (run-around abscess)
Chronic: bolstered, erythematous nail folds with loss of the cuticle, transverse nail ridging (Beau lines), discoloration, and secondary nail dystrophy
Multiple digits, especially of the dominant hand, support chronic etiology
Granulation tissue at the nail folds suggests drug-induced (EGFR inhibitor, retinoid) paronychia
Classic findings
Tender, fluctuant, single-digit nail fold abscess after a hangnail (acute); bolstered, erythematous nail folds with absent cuticles on multiple digits in a dishwasher (chronic).
Differential diagnosis
Herpetic whitlow — Painful clear/cloudy vesicles on a single digit, often grouped; preceding tingling; do NOT incise — self-limited, treat with oral acyclovir/valacyclovir
Felon — Deep infection of the volar pulp space with severe throbbing pain and tense swelling; requires incision and drainage
Acute flexor tenosynovitis (Kanavel signs) — Fusiform digit swelling, flexed posture, pain on passive extension, tenderness along the tendon sheath; surgical emergency
Ingrown toenail (onychocryptosis) — Lateral nail plate impinges into the nail fold of the great toe; mechanical issue requiring nail edge avulsion if recurrent
Eczema of the nail folds — Chronic erythema and scaling without purulence; often as part of hand eczema
Squamous cell carcinoma of the nail unit — Chronic 'paronychia' that fails to heal; consider biopsy in any persistent unilateral case
Diagnostic workup
Diagnostic criteria
Clinical diagnosis. Acute paronychia is recognized by acute fluctuant inflammation of the nail fold. Chronic paronychia is diagnosed by inflammation lasting more than 6 weeks affecting one or more nail folds with loss of the cuticle in a patient with wet-work or irritant exposure.
Labs
Wound culture if abscess drained, especially in immunocompromised or recurrent cases (rule out MRSA, gram-negative, anaerobic, Candida)
HSV PCR or Tzanck if herpetic whitlow suspected
KOH/PAS or fungal culture in chronic disease to document Candida
Glucose / HbA1c in recurrent or refractory chronic paronychia
Medication review for EGFR inhibitors, retinoids, antiretrovirals
Imaging
Plain radiograph if osteomyelitis or foreign body suspected, particularly in diabetics
Ultrasound can identify deep abscess if exam is equivocal
Diagnostic algorithm
Feature
Acute Paronychia
Chronic Paronychia
Herpetic Whitlow
Duration
<6 weeks
>6 weeks
Recurrent, brief episodes
Number of digits
Usually one
Often multiple
One
Etiology
Bacterial (S. aureus, strep)
Dermatitis + Candida
HSV-1 or HSV-2
Pain pattern
Throbbing, fluctuant
Mild-moderate, persistent
Burning, prodrome
Lesion
Purulent abscess
Bolstered red folds, absent cuticle
Clear/cloudy grouped vesicles
Risk factors
Hangnail, biting
Wet work, EGFR inhibitors, retinoids
Dental work, herpes labialis
First-line therapy
Incision and drainage
Avoid water; topical steroid + antifungal
Oral antiviral; do NOT incise
Differentiating acute paronychia, chronic paronychia, and herpetic whitlow.
Treatment
First-line
Acute, early/no abscess: warm soaks, topical antiseptic (chlorhexidine, povidone-iodine), topical mupirocin or fusidic acid; cover with bandage
Acute with fluctuant abscess: incision and drainage with a scalpel blade or 18-gauge needle inserted between the nail plate and the nail fold; no anesthesia required for simple drainage; oral antibiotics usually unnecessary if drained adequately
Add oral antibiotics with cellulitis, immunocompromise, diabetes, or extensive disease — cephalexin or dicloxacillin; if MRSA risk: TMP-SMX, doxycycline, or clindamycin; add amoxicillin-clavulanate if oral contamination/anaerobes likely
Chronic: rigorous avoidance of moisture and irritants (gloves with cotton liners), barrier emollients, topical high-potency corticosteroid (clobetasol, betamethasone dipropionate) for 2-3 weeks — primary anti-inflammatory therapy; topical antifungal (clotrimazole, ketoconazole, ciclopirox) as adjunct
Second-line / adjunct
Topical tacrolimus 0.1% ointment for chronic paronychia recalcitrant to steroids
Oral antifungal (fluconazole, itraconazole) if heavy Candida growth and topical fails
For herpetic whitlow: oral acyclovir 400 mg three times daily × 7-10 days (or 200 mg 5 times daily) or valacyclovir 1 g BID × 7-10 days; do NOT incise — risk of bacterial superinfection and dissemination
Treat drug-induced paronychia: topical/intralesional steroids, silver nitrate or topical timolol for granulation tissue, dose adjustment of offending drug, surgical removal of granulation; reassure that lesions often improve with continued therapy or after discontinuation
Complications
Acute: spread to felon, deep space infection, flexor tenosynovitis, osteomyelitis of the distal phalanx
Chronic: persistent nail dystrophy (Beau lines, ridging, dyschromia)
Herpetic whitlow incised in error: bacterial superinfection, dissemination
Drug-induced paronychia: chronic discomfort and granulation interfering with function — may necessitate dose modification of life-saving oncology agents
PANCE pearls
Treat acute paronychia with drainage, not antibiotics alone — adequate drainage is the cure.
Always consider herpetic whitlow before incising a vesicular nail fold lesion; HSV-related whitlow is not pus and should NOT be cut.
Chronic paronychia is dermatitis with secondary infection — topical steroids, not antifungals, are first-line.
Loss of the cuticle (eponychium-nail plate seal) is the hallmark of chronic paronychia.
Recurrent, multi-digit paronychia in a patient on an EGFR inhibitor (cetuximab) or retinoid is drug-induced and requires steroid and granulation management more than antimicrobials.
Any unilateral, persistent 'paronychia' that fails standard therapy deserves biopsy to exclude squamous cell carcinoma.
References
AFP 2017 — Leggit JC. Acute and chronic paronychia (American Family Physician 2017)
AAD review — Rigopoulos D et al. Acute and chronic paronychia (Am Fam Physician 2008; updated AAD reviews)
IDSA SSTI 2014 — Stevens DL et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections (Clin Infect Dis 2014)
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