Dystrophic Nails

Nail Matrix: The area responsible for nail growth.
- Proximal Nail Matrix
- Distal Nail Matrix
Eponychium (Cuticle): Translucent skin overlapping the nail.
Lunula: Whitish, semi-moon structure at the base of the nail.
Nail Plate: The hard, visible part of the nail.
Hyponychium: Area under the nail, more distally.
Nail Bed: Area under the nail plate.
Dermoscopy: A clinical examination technique that allows visualization of capillary loops within the nail matrix.
- A low-cost alternative to a dermoscope is using KYJELI and an ophthalmoscope.

Refers to any abnormality in the nail plate, including changes in:

A cornerstone of approach to nail dystrophy should include information about:

Onset
Progression (from start to current state; whether it's static, improving, or worsening)
Effect on nail growth
Patient exposures (internal, like systemic diseases, or external, like work environment or salon visits)
Consequences for the patient:
- Functional (e.g., inability to perform tasks, pain)
- Psychological (e.g., body dysmorphism)

Are all nails affected, or only some?
Pattern of involvement (hands vs. feet, asymmetrical, limited to certain nails, a particular limb)
Associated skin changes elsewhere on the body?
General condition of the patient and signs of other systemic illnesses?

Distribution: Is the nail dystrophy symmetrical (affecting all nails) or asymmetrical (affecting some nails)?
- Symmetrical: Usually indicates a global process from an endogenous cause (systemic diseases or global exposures).
- Asymmetrical: Indicates local processes or specific exposures.

Systemic Diseases
- Multisystem diseases that also manifest in the skin and nails.
- Skin diseases with nail manifestations.
Exposures
- Can be symmetrical or asymmetrical depending on the nature of the exposure.
- Drugs that are taken orally will then subsequently have consequences on all your nails in a uniform pattern.
- Environmental exposures will really depend on how the patient engages with that environmental exposure and which nails are in contact with the exposure.

Clubbing
- Causes:
  - 40% congenital
  - Cardiac (e.g., infective endocarditis, cyanotic heart diseases)
  - Respiratory (e.g., suppurative lung diseases like lung abscesses, empyema, bronchiectasis)
  - Gastrointestinal (e.g., inflammatory bowel diseases)
- Clinical Exam:
  - Loss of angle of the nail bed.
  - Shamrock's sign.
Koilonychia (Spoon-Shaped Nails)
- Can be normal in infancy.
- In older individuals, associated with iron deficiency anemia.
Splinter Hemorrhages
- Red-brown longitudinal lines due to leaky capillaries in the nail bed (do not blanch with pressure).
- Causes range from trauma (may be asymmetrical) to infective endocarditis (in only about 15% of infective endocarditis patients).
- Assess risk factors for infective endocarditis.

Psoriasis
- Autoimmune condition that can be limited to the skin or part of systemic disease as in psoriatic arthritis
- Erythematous plaques typically on the extensor surfaces with scale.
- Plaques with both the Kubner phenomenon and Horschmidt's sign.
- Nail signs:
  - Oil spots
  - Subungual hyperkeratosis
  - Pitting

Drugs
- Oral medications generally cause symmetrical nail changes.
- Changes can occur weeks or months after drug initiation.
- Effects:
  - Color changes: tetracyclines can cause photosensitivity, nail discoloration
  - Onycholysis
  - Changes in nail growth (e.g., nail plate deformity induced by Tretin)
  - Melonichiae: cidovudine or AZT can cause these linear bands of hyperpigmentation within your nail plate.
Nail Cosmetics
- Can cause symmetrical or asymmetrical effects, depending on application.
  - Onycholysis to artificial nail and glue, and then this paronychiae, which is affecting most of the nails as a reaction to nail enamel.

Onychomycosis (Fungal Infection of the Nail)
- Predisposing factors: increasing age, male sex, diabetes mellitus, immune suppression.
- Clinical presentation can affect nails only or both nails and skin.
- Distribution: can be one nail, multiple nails, feet, or "one hand, two feet" syndrome.
- Effect on nail: distal subungual, superficial white, or proximal subungual phenotypes.
- Diagnosis: Microscopy, culture, and sensitivity of nail clippings.
  - In saline: microscopy and culture.
  - In formalin: histology.
Paronychia (Inflammation of the Nail Fold)
- Timeline:
  - Acute: Less than six weeks; often associated with acute trauma (nail biting, manicures, ingrown toenails).
  - Chronic: More than six weeks; associated with persistent irritant exposures (wet work, irritant or contact dermatitis).
- Etiology:
  - Acute: Often infectious (Staph aureus, Strep pyogenes, herpes simplex).
  - Chronic: Damage to cuticle allows irritants and secondary infection (Candida albicans).

34-year-old female with a 3-month history of a new rash. Examination shows red, scaly plaques on extensor surfaces and nail changes (subungual hyperkeratosis and pitting) on hands and feet.
- Symmetrical nail dystrophy.
- Primary skin disease.
- Most likely diagnosis: psoriasis.
40-year-old diabetic man presenting for routine follow-up. Asymptomatic. Annual foot screening reveals asymmetrical nail dystrophy, predominantly affecting the hallux with distal nail changes.
- Asymmetrical nail dystrophy.
- Risk factor: diabetes (possible immunosuppression).
- Most likely diagnosis: onychomycosis.
22-year-old female on dialysis for end-stage renal disease, feeling more short of breath than usual. Cardiorespiratory exam is normal, but nails show abnormal shape/contour (koilonychia).
- Symmetrical nail changes (koilonychia).
- Systemic disease (end-stage renal disease) predisposing to iron deficiency anemia.