Finger and toe infections

Last updated: February 16, 2022

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Finger and toe infections are common conditions with a variety of causes, frequently manifesting with classic signs of inflammation. The most common types of finger infections are paronychia, felon, and herpetic whitlow; an ingrown toenail is the most common cause of toe infection. All of these conditions are clinical diagnoses. Treatment depends on the type and severity of the infection, but should not be delayed to prevent potentially severe complications, such as cellulitis, osteomyelitis, and soft tissue necrosis. Paronychias are acute or chronic inflammations of the nail folds, most commonly of the fingernails. Acute paronychia is typically caused by bacterial infection following trauma to the nail folds. The cause of chronic paronychia is multifactorial, although continuous exposure to moisture and/or skin irritants (e.g., dishwashing soap) often plays a role. Acute paronychia is frequently treated with topical antibiotics, while chronic paronychia is treated with topical steroids and avoidance of stressors. Felons are subcutaneous infections of the finger pulp, most commonly caused by bacterial infection secondary to minor trauma or progression of untreated acute paronychia. Early stages can be managed conservatively with analgesics and oral antibiotics; later stages, characterized by abscess formation, require incision and drainage. Herpetic whitlows are infections of the fingers caused by herpes simplex virus that typically manifest with nonpurulent vesicles and signs of inflammation over the pulp of the distal phalanx (see “Herpes simplex virus infections” for a more detailed discussion). An ingrown toenail is the abnormal growth of a nail plate into the lateral periungual skin of the nail fold. This condition most commonly affects the big toe and is often associated with improper trimming of the toenail. The disruption of the cutaneous barrier by the ingrown toenail results in an inflammatory foreign body reaction with the risk of subsequent infection. While conservative management involving the placement of cushioning material (e.g., cotton) under the ingrown nail plate may be sufficient in early stages, partial nail avulsion or complete nail excision is necessary eventually.

Paronychia [1][2]

Overview of paronychia
Types Acute paronychia Chronic paronychia
Definition
Epidemiology
  • Sex: > (3:1)
  • Most common in professions involving manual labor where trauma to the nail folds or exposure to moisture and/or skin irritants is common (e.g., domestic workers, dishwashers)
Etiology
  • Most commonly caused by chronic exposure to skin irritants (e.g., household chemicals)
  • Rarely caused by infections
Pathogenesis
  • Trauma (e.g., nail-biting, manicuring) → disruption of the barrier between the nail plate and the nail fold bacterial infection
  • Multifactorial disruption of the barrier between the nail plate and the nail fold (e.g., trauma, skin irritants) → persistent exposure to skin irritants → eczematous inflammatory reaction
Clinical features
Diagnosis
Treatment
Complications

Felon (pulp space infection) [3][4]

Blistering distal dactylitis [5][6]

Herpetic whitlow [3]

Ingrown toenail (onychocryptosis, unguis incarnatus) [7][8]

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  2. Mayeaux EJ Jr, Carter C, Murphy TE. Ingrown Toenail Management.. Am Fam Physician. 2019; 100 (3): p.158-164.
  3. Levy L. Prevalence of chronic podiatric conditions in the US. National Health Survey 1990. J Am Podiatr Med Assoc. 1992; 82 (4): p.221-223. doi: 10.7547/87507315-82-4-221 . | Open in Read by QxMD
  4. Leggit JC. Acute and Chronic Paronychia.. Am Fam Physician. 2017; 96 (1): p.44-51.
  5. Relhan V, Goel K, Bansal S, Garg VK. Management of chronic paronychia. Indian J Dermatol. 2014; 59 (1): p.15-20. doi: 10.4103/0019-5154.123482 . | Open in Read by QxMD
  6. Rerucha CM, Ewing JT, Oppenlander KE, Cowan WC. Acute Hand Infections.. Am Fam Physician. 2019; 99 (4): p.228-236.
  7. Nardi NM, McDonald EJ, Schaefer TJ. Felon. StatPearls. 2021 .
  8. Anjaneyan G, Kaliyadan F. Blistering Distal Dactylitis. StatPearls. 2021 .
  9. Kowtoniuk R, Bednarek R, Maroon M. Blistering Distal Dactylitis. JAMA Dermatology. 2018; 154 (12): p.1480. doi: 10.1001/jamadermatol.2018.3345 . | Open in Read by QxMD

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