What Causes Nail Psoriasis?

Nail psoriasis can cause nail thickening, malformation, and discoloration.

Nail psoriasis or psoriatic nail dystrophy is psoriasis involving the nail matrix, nail bed hyponychium and nail folds of a few digits (fingernails and toenails), resulting in specific and nonspecific clinical changes in the nail.

It is estimated that approximately 50% of people with chronic plaque psoriasis will experience nail changes at the time of their initial diagnosis, whereas 90% will experience significant nail changes at some point in their life.

Nail psoriasis is caused by the same autoimmune mechanisms as other types of psoriasis. The immune system attacks normal tissues in the body and triggers the hyperproliferation of cells.

In the fingernails and toenails, this immune system malfunction causes nail cells to be produced faster than they can be shed, leading to nail thickening, malformation, and discoloration.

Symptoms of nail psoriasis vary from person to person and can keep changing as the disease progresses.

Common signs of nail psoriasis include:

• Tiny dents or pitting of the nail surface (nail pits)
• White, yellow, or brown discoloration
• Crumbled, rough, and brittle nails
• Nails seem to be separated from the finger or toe
• Lines and furrows (called Beau's lines) that run side to side
• Subungual hyperkeratosis (thickening of the nail)
• Yellowish-red dots under the nail (oil drop sign or salmon patches)
• Leukonychia (white patches on the nails)
• Longitudinal nail ridge, split, or fissure (onychorrhexis)
• Debris accumulation underneath the nail
• Splinter hemorrhages (tiny black lines that run from the tip to the cuticle under the distal third of the nail plate are caused by burst capillaries)
• Onycholysis (lifting or separation of the nail plate)
• Spotted lunula (redness in the white arch at the base of the nail)
• Psoriatic arthritis (arthritis in the finger or toe with nail damage)

Psoriatic nail disease may be a risk factor for the development of psoriatic arthritis and is often associated with prolonged severe cutaneous psoriasis.

If nail psoriasis occurs on its own without the classic symptoms of other types of skin psoriasis, it is often difficult to diagnose and may be easily confused for other conditions, including:

• Alopecia areata (an autoimmune disease characterized by hair loss and nail damage)
• Lichen planus (an inflammatory condition affecting the skin, nails, and hair)
• Onychomycosis (a common fungal infection of the nail)
• Pityriasis rubra pilaris (a rare disorder characterized by skin inflammation, thickening of nails, and hair loss)
• Parakeratosis pustulosa

Nail psoriasis is primarily diagnosed in a patient with psoriatic arthritis and/or cutaneous psoriasis by a physical examination and a medical history analysis (including the family history of skin disorders).

In some cases, additional tests may be recommended such as:

• Nail clippings for fungal microscopy and culture
• Nail matrix biopsy
• Nail psoriasis severity index (severity of nail psoriasis is estimated by dividing each nail into quadrants and scoring for clinical signs to come up with a numerical score)

Because it takes around three months to regrow a fingernail and six months to regrow a toenail, treatment of nail psoriasis is often slow and difficult.

Successful treatments may take time before the nail looks normal again and may include:

• Topical corticosteroids
  • Helps reduce localized inflammation.
  • Recommended to use 1-2 times a day for up to 9 months.
  • Overuse can lead to permanent skin thinning (atrophy) in the treated area.
• Calcipotriol
  • Vitamin D derivative that is applied topically twice daily to the affected nail.
  • Acts as a potent corticosteroid for treating the buildup beneath the nail.
• Tazarotene
  • Topical retinoid product helpful for treating pitting, separating, and discoloration.
• Steroid injections
  • Delivered in small doses directly into or near the structure of the nail unit.
  • Triamcinolone acetonide is the most commonly used intralesional steroid, with pain being the most common side effect of treatment.
• Systemic therapies
  • Involves medications that temper the underlying immune response that triggers nail malformation:
    • Disease-modifying anti-rheumatic drugs such as methotrexate and cyclosporine (Sandimmune)
    • Retinoids such as acitretin
• Biologics
  • Tumor necrosis factor alpha inhibitors
  • Adalimumab (Humira)
  • Certolizumab pegol (Cimzia)
  • Etanercept (Enbrel)
  • Etanercept-szzs (Erelzi)
  • Infliximab (Remicade)
  • Interleukin-17 inhibitors
  • Brodalumab (Siliq)
  • Ixekizumab (Taltz)
  • Secukinumab (Cosentyx)
  • Interleukin-23 inhibitors
  • Guselkumab (Tremfya)
  • Tildrakizumab (Ilumya)
  • Interleukin 12 and 23 inhibitor
  • Ustekinumab (Stelara)
• Phototherapy
  • Ultraviolet (UV) lamps have proven beneficial in treating plaque psoriasis; it is also effective in treating oil spots in nails.
• Psoralen plus ultraviolet A (PUVA)
  • Involves first soaking in medicine called psoralen and then carefully exposing to UVA rays, which is effective for treating discolored nails and nails that are separating from fingers or toes.
• Pulse dye laser and photodynamic therapy
  • Involves targeting laser beams to affected areas.

Nail psoriasis can lead to progressive damage to fingernails and toenails. Without treatment, nail psoriasis can worsen and lead to "disappearing" nails or nail dystrophy, which can affect your ability to use your hands or walk.

Nail psoriasis can cause significant pain, making it difficult to walk, do daily routine activities, or perform manual labor. The condition can also impact social relationships and work-related activities, making a person extremely self-conscious and uncomfortable.

One of the best ways to treat and prevent nail psoriasis includes taking measures such as:

• Keeping nails trimmed and short
• Keeping nail edges smooth by using a nail filer
• Wearing gloves when cleaning and doing other routine chores
• Moisturizing your nails and cuticles often
• Wearing comfortable and airy shoes with enough room for your toes