Pitting & Trachyonychia
Nail pitting and trachyonychia (twenty-nail dystrophy) are two characteristic clinical signs of chronic inflammation and disordered keratinocyte differentiation in the proximal nail matrix — the anatomical region that produces the upper (dorsal) layer of the nail plate.
Pathogenesis by type of damage:
- Nail pitting:
- Arises from focal inflammatory foci in the proximal nail matrix.
- In these foci, normal keratinization is disrupted, producing clusters of abnormal, nucleated keratinocytes (parakeratotic cells).
- As the nail plate grows out toward the free edge, these unstable parakeratotic clusters are exposed to the environment, quickly degrade, flake and fall away, leaving small depressions (pits) on the dorsal surface of the nail plate.
- Trachyonychia:
- Arises from widespread, continuous inflammation (diffuse inflammatory involvement) of the entire proximal nail matrix.
- Cell division and keratinization are severely disrupted across a wide area, so the nail plate grows out having lost its natural shine. It develops numerous fine longitudinal ridges and becomes rough, brittle and prone to splitting, with a dull surface as if rubbed with sandpaper (sandpaper nails).
Underlying Causes
- Alopecia areata: The leading cause of trachyonychia in children and of uniform, geometric pitting in adults. An autoimmune reaction attacks both hair follicles and the nail matrix.
- Nail psoriasis: Causes deep, large, irregularly distributed pits (a "honeycomb" or "coarse" pitting pattern).
- Atopic dermatitis / eczema: Causes shallow pits, along with transverse ridges and nail plate deformity from inflammation of the proximal nail fold.
- Nail lichen planus: Presents as opaque trachyonychia and can progress to scarring that destroys the nail matrix (dorsal pterygium) if not treated early.
Nail pitting and trachyonychia are not merely cosmetic problems; they reflect an underlying autoimmune condition. At Haute-Derma, our doctors never treat rough or pitted nails by aggressively filing down the nail plate. Every patient undergoes high-magnification onychoscopy (nail dermoscopy) to assess the pit structure and the capillaries of the proximal nail fold. This allows us to accurately distinguish psoriasis, alopecia areata and lichen planus, and then prescribe treatment that targets inflammation directly at the nail matrix.
Clinical Features & Morphological Classification
- Nail pitting:
- Small depressions on the nail plate surface, 0.5 mm to 2 mm in diameter.
- Shallow, small pits in straight lines or geometric patterns: Common in alopecia areata.
- Deep, large, irregularly scattered pits: Common in nail psoriasis.
- Trachyonychia:
- The nail surface loses its translucency and turns dull grey, with hard, rough longitudinal ridges.
- The nail plate is brittle and splits easily at the free edge (onychoschizia), and the surrounding nail folds may be red, inflamed or slightly scaly.
Morphological Types of Trachyonychia
- Opaque trachyonychia: The most severe and typical form. Every nail plate is covered with hard longitudinal ridges, the surface is as rough as sandpaper, and the nails are a dull pale grey. Often associated with lichen planus or psoriasis.
- Shiny (semi-opaque) trachyonychia: A milder form. The nail remains semi-translucent, but the surface is covered in small, shallow geometric pits that reflect light when viewed at an angle. Often associated with alopecia areata.
Diagnosis & Advanced Treatment at Haute-Derma
The core principle in treating nail pitting and trachyonychia is to target the inflammation directly in the proximal nail matrix, which lies about 5–8 mm beneath the proximal nail fold. Treatments applied only to the surface of the hard nail plate are almost entirely ineffective.
In-Clinic Diagnosis
- Onychoscopy (nail dermoscopy): Assesses pit density, ridge pattern, and the presence of splinter hemorrhages or dilated capillaries at the proximal nail fold.
- Full clinical examination: Looks for skin and hair involvement (alopecia areata), psoriasis plaques or eczema patches elsewhere on the body.
- Nail matrix biopsy: Performed only when trachyonychia affects a single nail and a tumor is suspected, or in rapidly progressing lichen planus that causes scarring.
Treatment by Severity
- Topical occlusive therapy:
- For children or mild cases: a potent topical corticosteroid (clobetasol propionate 0.05% or betamethasone dipropionate) applied under occlusion to the proximal nail fold at night for 8–12 weeks.
- For psoriasis-related cases, add daily tazarotene 0.05% or calcipotriol (a vitamin D3 analogue).
- Intralesional corticosteroid injection:
- The gold standard for adults with severe pitting or progressive trachyonychia.
- Technique: Triamcinolone acetonide (2.5–5 mg/ml) injected directly into the proximal nail fold (the nail matrix area), once a month for 3–6 months.
- Systemic therapy:
- Indicated when trachyonychia affects all 20 nails (twenty-nail dystrophy) together with extensive alopecia areata or severe psoriasis.
- Short courses of oral corticosteroids, acitretin, cyclosporine, or JAK inhibitors (tofacitinib, baricitinib) achieve very high rates of nail recovery.
