A 43-Year-Old Man with a Painful, Purulent Finger

Differential Diagnosis

• Nail candidiasis
• Felon
• Bacterial paronychia
• Nail bed injury

Diagnosis

This patient was diagnosed with bacterial paronychia. Acute paronychia is defined as inflammation of the proximal or lateral nail folds for fewer than 6 weeks. Pain, swelling, and redness are the cardinal symptoms, sometimes accompanied by abscess formation.

Acute paronychia frequently arises from trauma to one of the nail folds, resulting in compromise of the physiologic barrier to entry of microorganisms. Inflammation may proceed to bacterial infection, resulting in pus.

Learnings/What to Look for

• In some cases, the abscess tracks under the nail plate; if not treated quickly, it can result in permanent damage to the nail matrix
• Examples of inciting trauma include foreign bodies, such as splinters; manipulations, such as manicures or pedicures; ingrown nails; fingernail biting; finger sucking in children; or “hangnail” removal
• Occasionally, acute paronychia arises as a painful exacerbation of chronic paronychia, which is now understood to be a localized form of chronic irritant or allergic dermatitis
• Certain drugs, including retinoids (isotretinoin, acitretin), methotrexate, antiretroviral protease inhibitors (indinavir, lamivudine), and epidermal growth factor receptor inhibitors (cetuximab, gefitinib, lapatinib) can cause drug-induced paronychia, in some cases with associated periungual lobular capillary hemangioma (pyogenic granuloma)

Pearls for Urgent Care Management

• Mild paronychia calls for conservative treatment (warm water soaking, topical antibiotics with or without topical steroids)
• Abscesses call for drainage
• Specific bacteria predominate in trauma-related acute paronychia; indicated antibiotic treatment for infection with Staphylococcus aureus, Streptococcus pyogenes, and anaerobic bacteria derived from the oral flora is warranted

Acknowledgment: Images and case presented by VisualDx (www.VisualDx.com/JUCM).