What can cause an outgrowth on the lateral aspect of the nail bed of the finger in the setting of a paronychia (infection of the nail fold) or hangnail (onychocryptosis)?

From the Guidelines

A hangnail can lead to an outgrowth on the lateral aspect of the nail bed, most commonly due to Candida paronychia, which is a type of fungal infection that can cause inflammation and infection of the nail folds, including the lateral margins. This condition is more common in individuals who frequently immerse their hands in water, and the fourth and fifth fingers are less frequently affected than the thumbs and middle fingers 1. The infection often starts in the proximal nail fold but can also affect the lateral margins, causing the periungual skin to become swollen, erythematous, and painful.

Some key characteristics of Candida paronychia include:

• Swollen, erythematous, and painful periungual skin
• A prominent gap between the fold and the nail plate
• White, green, or black marks on the nail plate
• Transverse or longitudinal furrowing or pitting of the nail
• Friable nail that may become detached from its bed
• Painful pressure on and movement of the nail

Treatment for Candida paronychia typically involves addressing the underlying fungal infection, and may include the use of antifungal medications, as well as measures to reduce inflammation and prevent further irritation. It is essential to keep the area clean and dry, avoid picking at hangnails, trim nails properly, and use moisturizer around the nails to prevent recurrence. In severe cases, bacterial superinfection may occur, making it challenging to determine the cause of the nail damage, and requiring additional treatment with antibiotics 1.

From the Research

Causes of Outgrowth on the Lateral Aspect of the Nail Bed

In the setting of a hangnail, several factors can contribute to the development of an outgrowth on the lateral aspect of the nail bed of the finger. These include:

• Bacterial infections, such as Staphylococcus aureus or Streptococcus, which can cause acute paronychia 2, 3
• Fungal infections, including onychomycosis due to moulds (Fusarium) or dematiaceous fungi (Scytalidium dimidiatum) 2
• Viral infections, such as herpetic whitlow 2
• Contact dermatitis, either irritant or allergic, which can lead to chronic paronychia 2, 3, 4
• Systemic conditions, such as those requiring chemotherapy or targeted therapies, which can increase the risk of paronychia 2
• Non-infectious etiologies, including chemical irritants, excessive moisture, and nail changes due to systemic conditions or medications 3

Associated Conditions

Outgrowth on the lateral aspect of the nail bed can also be associated with other conditions, including:

• Ingrown nail, either lateral or proximal (retronychia) 2
• Candida spp or bacterial infections, which can overlap with paronychia 4
• Psoriatic paronychia, lichen planus of the nails, or other dermatological conditions 4