12.2 Nail Disorders and Diseases

Nail Disorders and Diseases

Exam Focus: Learn the disorders that can be serviced with modification and the diseases that cannot, and learn the two visual signals that most reliably indicate a refusal: any green or greenish-black discoloration, and any inflammation, swelling, heat, pus or broken skin around the nail.

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1. Non-Infectious Nail Disorders (Salon Serviceable with Modifications)

A nail disorder is a non-infectious cosmetic irregularity, structural imperfection, or mechanical injury affecting the nail unit. Unless the skin is broken, inflamed, bleeding, or infected, cosmetologists may perform services with appropriate protective adaptations.

┌─────────────────────────────────────────────────────────────────────────────┐
│                     NON-INFECTIOUS NAIL DISORDERS                           │
├─────────────────────┬─────────────────────────────────┬─────────────────────┤
│ Disorder Name       │ Observable Clinical Signs       │ Etiology / Care     │
├─────────────────────┼─────────────────────────────────┼─────────────────────┤
│ Leukonychia         │ White spots or streaks on plate │ Minor matrix injury │
│ Melanonychia        │ Dark pigmented lengthwise bands │ Melanin deposition  │
│ Onychophagy         │ Severely bitten, shortened nails│ Habitual chewing    │
│ Onychorrhexis       │ Split, brittle, lengthwise ridges│ Dehydration/chemicals│
│ Hangnail (Agnail)   │ Split living skin at eponychium │ Dry skin/improper cut│
│ Beau's Lines        │ Transverse horizontal grooves   │ Severe illness/fever│
│ Splinter Hemorrhage │ Tiny vertical red/black streaks │ Capillary trauma    │
│ Plicatured Nail     │ "Folded nail"; highly curved 90°│ Heredity or shoes   │
└─────────────────────┴─────────────────────────────────┴─────────────────────┘

Clinical Analysis of Key Disorders

• Leukonychia (White Spots): Characterized by white spots or whitish discoloration across the nail plate. Caused by minor mechanical trauma to the matrix (e.g., striking the base of the nail) that traps tiny air bubbles between keratin layers. Leukonychia is harmless, cannot be removed by buffing, and gradually grows out with the natural nail plate.
• Melanonychia: Darkening of the fingernails or toenails presenting as a black or brown band extending lengthwise from proximal fold to free edge. Caused by localized hyperpigmentation from active melanocytes in the matrix. While normal and common in individuals with darker skin tones, a sudden, isolated new band appearing in a fair-skinned individual requires medical referral to rule out subungual malignant melanoma.
• Onychophagy (Bitten Nails): The medical term for nails deformed by habitual chewing or biting of the nail plate and surrounding skin. Safe to service; frequent manicures, hot oil treatments, and artificial enhancements often assist in breaking the habit.
• Onychorrhexis: Split, brittle nails exhibiting pronounced vertical lengthwise ridges and surface roughness. Caused by excessive exposure to harsh alkaline cleaners, drying solvents (acetone), aggressive filing, or nutritional/aging factors. Managed with gentle filing, moisturizing cuticle oils, warm oil manicures, and avoiding coarse buffers.
• Hangnails (Agnails): A condition where living skin around the nail plate (usually lateral sidewalls or eponychium) splits and tears. Caused by extreme cutaneous dryness or improperly cutting living tissue. Cosmetologists may soften the area with oil and carefully trim only the loose, dead tag of skin; never pull, tear, or cut living vascular tissue.
• Beau's Lines: Visible horizontal depressions or transverse furrows running across the width of the nail plate. Caused when severe systemic illness (such as pneumonia, high prolonged fever, uncontrolled diabetes, or major surgery) temporarily arrests matrix cell division. As health resumes, the groove grows out distally.
• Splinter Hemorrhages: Small, thin, lengthwise red or brownish-black lines beneath the nail plate that resemble embedded wood splinters. Caused by physical trauma or localized microvascular damage to the delicate parallel capillaries of the nail bed.
• Onychocryptosis (Ingrown Nails): The nail plate curls and grows into the lateral soft tissue sidewalls, causing pressure and irritation. If there is no redness, inflammation, broken skin, or infection, a cosmetologist may carefully round the edge lightly. However, if the area is inflamed, swollen, draining pus, or deeply embedded, the technician must refuse service and refer the client to a podiatrist or physician.
• Eggshell Nails: Noticeably thin, white, highly flexible nail plates that curve over the free edge. Caused by improper diet, hereditary weakness, internal disease, or medication. Requires delicate handling with a fine-grit abrasive (240 grit or higher).

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2. Infectious Nail Diseases & Pathologies (Strict Contraindications)

An infectious nail disease is caused by pathogenic microorganisms (fungi, bacteria, or viruses). Any client exhibiting visible signs of inflammation, redness, swelling, heat, throbbing pain, pus exudate, or severe fungal dystrophies MUST BE REFUSED SERVICE IMMEDIATELY and referred to a physician or dermatologist. Cosmetologists are legally barred from diagnosing or treating diseases.

┌─────────────────────────────────────────────────────────────────────────────┐
│            INFECTIOUS NAIL DISEASES — MANDATORY SERVICE REFUSAL             │
├───────────────────────────┬─────────────────────────────┬───────────────────┤
│ Disease / Pathology       │ Causative Microorganism     │ Primary Symptoms  │
├───────────────────────────┼─────────────────────────────┼───────────────────┤
│ Onychomycosis / Tinea     │ Fungal Dermatophytes        │ Thick, yellow,    │
│ Unguium                   │ (Trichophyton rubrum)       │ crumbly, separated│
├───────────────────────────┼─────────────────────────────┼───────────────────┤
│ Paronychia                │ Bacterial (Staph / Strep)   │ Red, hot, swollen │
│                           │ or Fungal (Candida albicans)│ tissue at fold/pus│
├───────────────────────────┼─────────────────────────────┼───────────────────┤
│ Pseudomonas aeruginosa    │ Bacterial (Pseudomonas)     │ Green/black stain,│
│ ("Green Nail Syndrome")   │ Opportunistic pathogen      │ moisture beneath  │
├───────────────────────────┼─────────────────────────────┼───────────────────┤
│ Onychia                   │ Bacterial / Mixed Pathogens │ Matrix inflammation│
│                           │                             │ & plate shedding  │
├───────────────────────────┼─────────────────────────────┼───────────────────┤
│ Pyogenic Granuloma        │ Vascular / Bacterial        │ Bright red lump of│
│                           │                             │ granulation tissue│
└───────────────────────────┴─────────────────────────────┴───────────────────┘

Clinical Profile of Mandatory Referral Diseases

• Onychomycosis (Tinea Unguium): A contagious fungal infection of the natural nail plate. Fungal dermatophytes invade the subungual space, causing the nail plate to become thick, discolored (whitish, yellowish, or brownish patches), brittle, distorted, and crumbly, often separating from the nail bed. Strict contraindication: Refuse all manicuring, pedicuring, or enhancement applications.
• Paronychia: A localized bacterial or fungal infection of the living soft tissue folds surrounding the nail plate (eponychium and perionychium). Manifests as acute redness, swelling, intense throbbing pain, localized warmth, and visible pus accumulation. Frequently contracted through unsanitary cuticle trimming or aggressive picking. Strict contraindication: Refuse all services.
• Pseudomonas aeruginosa ("Green Nail Syndrome"): A bacterial infection caused by Pseudomonas aeruginosa, an opportunistic bacterium that thrives in warm, moist, stagnant environments. When natural nail plates separate from enhancements or when artificial enhancements lift, water and oils become trapped. The bacteria multiply rapidly, secreting pyocyanin—a dark green/blackish pigment.
  • Historical Misconception: In the past, this green discoloration was mistakenly referred to as "mold." Molds are extremely rare on living human nails; green stains are always bacterial.
  • Salon Action: If green discoloration is discovered upon removing an enhancement, remove all product, sanitize the area, and do not reapply artificial enhancements until the bacterial infection has been evaluated by a physician and fully resolved.
• Onychia: Acute inflammation of the nail matrix accompanied by pus formation and subsequent detachment and shedding of the natural nail plate. Requires medical antibiotic intervention.
• Pyogenic Granuloma: A severe, vascular inflammatory condition characterized by a round, vascular, bright red or purple nodule of granulation tissue projecting upward from the nail bed to the nail plate surface. Extremely sensitive and bleeds easily.
• Onycholysis: The painless loosening or separation of the natural nail plate from the underlying vascular nail bed, typically starting at the free edge and progressing toward the lunula. Caused by physical trauma, allergic contact dermatitis (from unreacted monomer liquid or acrylates), fungal infection, or harsh shoe pressure. If infection is absent, the lifted portion may be kept trimmed short; if signs of infection appear, refer to a physician.
• Onychomadesis: The complete separation and shedding of the nail plate from the matrix bed, beginning at the proximal cuticle fold. Caused by severe localized matrix trauma, systemic chemotherapy, or severe viral infections (such as hand, foot, and mouth disease).

3. The Refusal and Referral Protocol

The service stops the moment a disease or an inflamed condition is identified, and the sequence is fixed.

1. Stop and explain discreetly, at the station, without an audience.
2. Describe, do not diagnose. "There's a discoloration and some lifting here that I can't safely work over — a doctor should look at it before your next appointment."
3. Refer to a physician, dermatologist or podiatrist as appropriate.
4. Decontaminate. Every implement that touched the client goes through the full § 160.17(c) sequence; single-use items — emery boards, orangewood sticks, buffers, wipes — are discarded; the station and any bowl or footbath are cleaned and disinfected.
5. Wash hands with soap and water under § 160.20(e).
6. Document what was observed and that a referral was made, without recording a diagnosis.
7. Offer to rebook once the client has medical clearance.

4. Quick Discrimination Table

5. Preventing Salon-Caused Nail Problems

Several of the conditions a cosmetologist sees were caused by nail services, which makes prevention a professional duty.

• Do not cut living tissue. The eponychium is living skin. Cutting it removes the seal that protects the matrix and is the most common cause of paronychia after a manicure. Only the loose, non-living tissue adhering to the nail plate is removed.
• Do not over-file the natural plate before an enhancement. Aggressive etching thins the plate permanently and causes the flexibility and lifting that lets bacteria in.
• Do not apply an enhancement over a lifted, damaged or discoloured nail. Sealing moisture and bacteria under a product is exactly how pseudomonas develops.
• Do not use a drill or coarse abrasive at the cuticle area or on the natural nail without training and care.
• Remove enhancements properly. Prising or popping off an enhancement takes layers of nail plate with it.
• Diabetic clients: no implement that can abrade or cut the skin; light massage only; refer any callus, lesion or ingrown nail to a physician or podiatrist.