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Normal Nail Apparatus

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  • The nail apparatus is made up of:

    • Nail plate, the horny “dead” product.

    • Four specialized epithelia: proximal nail fold, nail matrix, nail bed, hyponychium.

    • Nail apparatus disorders can be traumatic, primary, manifestations of cutaneous disease (e.g., psoriasis), neoplastic, infectious, or manifestations of systemic diseases (e.g., lupus erythematosus).

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Components of the Normal Nail Apparatus

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(See Fig. 32-1)

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Figure 32-1.

Schematic drawing of normal nail.

Graphic Jump Location
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Local Disorders of Nail Apparatus

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Local disorders affecting the nail apparatus can result in a spectrum of chronic nail diseases.

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Chronic Paronychia

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ICD-9: 681.02 ○ ICD-10: L03.0 Image not available.

  • Associated with damage to cuticle: mechanical or chemical.

  • At risk: adult women, food handlers, house cleaners.

  • Chronic dermatitis of proximal nail fold and matrix: chronic inflammation (eczema, psoriasis) with loss of cuticle, separation of nail plate from proximal nail fold (Fig. 32-2).

  • Predisposing factors:

    • Dermatosis: psoriasis, dermatitis [atopic, irritant (occupational), allergic contact], lichen planus.

    • Drugs: oral retinoids (isotretinoin, acitretin), indinavir.

    • Foreign body: hair, bristle, wood splinters.

  • Manifestations: first, second, and third fingers of dominant hand; proximal and lateral nail folds erythematous and swollen; cuticle absent.

  • Intermittently, persistent low-grade inflammation may flare into subacute painful exacerbations, resulting in discolored transverse ridging of lateral edges.

  • Secondary infection/colonization: Candida spp., Pseudomonas aeruginosa, or Staphylococcus aureus. Nail plate may become discolored; green undersurface with Pseudomonas. Infection associated with painful acute inflammation.

  • Management:

    • Protection.

    • Treat the dermatitis with glucocorticoid: topical, intralesional triamcinolone, short course of prednisone.

    • Treat secondary infection.

Figure 32-2.

Chronic paronychia The distal fingers and periungual skin are red and scaling. The cuticle is absent; a pocket is present, formed as the proximal nail folds separate from the nail plate. The nail plates show trachonychia (rough surface with longitudinal ridging) and onychauxis (apparent nail plate thickening due to subungual hyperkeratosis of nail bed). The underlying problem is psoriasis. Candida albicans or Staphylococcus aureus can cause space infection in the “pocket” with intermittent erythema and tenderness of the nail fold.

Graphic Jump Location

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Onycholysis

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ICD-9: 703.8 ○ ICD-10: L60.1 Image not available.

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  • Detachment of nail from its bed at distal and/or lateral attachments (Fig. 32-3).

  • Onycholysis creates a subungual space that collects dirt and keratinous debris; area may be malodorous when the overlying nail plate is removed.

  • Etiology:

    • Primary: Idiopathic (fingernails in women; mechanical or chemical damage); trauma (fingernails, occupational injury; toenails, podiatric abnormalities, poorly fitting shoes).

    • Secondary: Vesiculobullous disorders (contact dermatitis, dyshidrotic eczema, herpes simplex); nail bed hyperkeratosis (onychomycosis, psoriasis, chronic contact dermatitis); nail bed tumors; drugs.

    • In psoriasis, yellowish-brown margin is visible between pink normal nail and white separated areas. In “oil spot” or “salmon-patch” variety (Fig. 32-3), nail ...

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