9.2 Nail Disorders & Diseases

Why This Section Decides Exam Scores

On the Tennessee exam, the nail-disorders content is almost always tested through judgment scenarios: a client sits down, the stem describes what you see, and you must choose between perform the service, modify the service, or decline and refer. To answer well you need three things memorized: the names, the appearances, and the one governing rule.

The governing rule: a cosmetologist may service a nail with a cosmetic disorder as long as it is not infected or inflamed, but must refuse service and refer to a physician whenever a nail shows signs of infection, disease, or an unexplained change. You recognize conditions; you never diagnose them. Telling a client "you have a fungus" is practicing medicine without a license — the correct phrasing is that you cannot perform the service and recommend they see a doctor.

Common Nail Disorders (Usually Serviceable)

A disorder is a non-infectious condition — a result of habit, injury, dryness, or internal factors — that generally does not prevent service, though you may need to work gently around it.

• Onychophagy: chronically bitten nails. The bitten free edge and surrounding skin may be ragged; careful manicuring can improve appearance and help the client break the habit.
• Hangnail (agnail): a small split or tear in the cuticle or skin at the side of the nail. Trim it carefully with nippers; never rip it, which tears living tissue and opens the door to paronychia.
• Pterygium: an abnormal forward growth of the cuticle skin that stretches onto and adheres to the nail plate. Gently push back and care for it; do not cut it away aggressively, because it is living skin.
• Onychorrhexis: split or brittle nails, often with lengthwise ridges. Associated with dryness, harsh chemicals, aging, or injury. Recommend conditioning treatments and gentle handling.
• Bruised nails: dark discoloration under the plate from trapped blood after trauma (a hammer blow, a slammed door). The bruise grows out with the nail; service is fine once tenderness subsides, but unexplained dark marks without a trauma history deserve referral.
• Eggshell nails: abnormally thin, soft, fragile plates that curve over the free edge like an eggshell. File gently and keep nails short.
• Corrugations: horizontal wavy ridges across the plate, usually from uneven growth in the matrix after illness or injury.
• Koilonychia: spoon nails — plates that are concave, dipping inward so they could hold a drop of water. This can be a sign of iron-deficiency anemia or other systemic issues; note it and suggest the client mention it to a physician.
• Melanonychia: dark bands or streaks of pigment running lengthwise in the nail. It is common and benign in people with darker skin tones, but a new, changing, or single dark band — especially one that widens or spreads pigment to the surrounding skin — must be referred promptly, because melanoma can appear under a nail. Caution, always.
• Leukonychia: white spots or streaks in the plate, almost always from minor matrix trauma (a bump weeks earlier), not — despite popular belief — a calcium deficiency. Harmless; grows out.
• Beau's lines: horizontal grooves or depressions running across the nail, marking a period when growth slowed or stopped due to high fever, serious illness, chemotherapy, or severe stress. The position of the groove even estimates when the illness occurred, given the ~1 mm per 10 days growth rate.

Nail Diseases and Infections (Do NOT Service — Refer)

A disease in this context means an infection or a condition involving living tissue inflammation. These are absolute contraindications: touching them risks spreading the infection to other clients, worsening the client's condition, and exposing you to liability.

• Onychomycosis: a fungal infection of the nail — literally ringworm of the nail (tinea unguium). The plate becomes thickened, discolored (yellow, brown, or white), crumbly, and may lift. Highly contagious between clients via implements. Refuse service; anything that contacted the nail must be disinfected or discarded.
• Paronychia: a bacterial infection of the skin around the nail (the nail fold), appearing red, swollen, warm, and often pus-filled. Also called a felon when the infection is acute and deep. Often starts from a ripped hangnail or over-aggressive cuticle cutting. Do not touch it — refer.
• Onychia: inflammation of the matrix itself, usually with pus formation, which can cause the nail to shed. Refuse and refer.
• Onychoptosis: the periodic shedding or falling off of part or all of a nail, often following onychia, trauma, or serious illness. Do not service the affected digit.
• Onycholysis: separation of the nail plate from the nail bed without the plate falling off — the free edge appears white or opaque as air fills the gap. Causes include trauma, over-filing under the free edge, harsh products, psoriasis, or fungal infection. Do not service: the open space traps moisture and debris and is an ideal breeding ground for infection. Refer, especially if the cause is unknown.
• Pyogenic granuloma: a rapidly growing, small, red, easily bleeding overgrowth of skin tissue, sometimes appearing near a nail after injury. A physician must treat it.
• Tinea manuum and tinea pedis: ringworm of the hands and feet — a fungal infection of the skin (not the nail) causing itching, scaling, redness, and sometimes blisters or peeling between toes. Extremely common in pedicure settings; refuse the service and disinfect the basin area thoroughly.

Telling a Cosmetic Issue from an Infection

Ask three questions during your inspection:

1. Is there redness, heat, swelling, pain, or pus? Any of these signals infection or inflammation — stop and refer.
2. Is it spreading or changing? A condition that grows, multiplies, or involves more nails over time is more likely infectious or systemic.
3. Can the client explain it? A bruise with a clear trauma story is different from an identical-looking mark with no explanation. Unexplained changes are referred.

Condition → Appearance → Service or Refer

When in doubt on the exam, choose refer. The safest professional answer is the correct one.