Nail Disorders Flashcards
Nail dystrophy
Abnormality of nail (not always fungal)
Onychonmycosis
Any fungal infection of the nail : Dermatophyte & non-Dermatophyte infection
Eg: Fusarium spp., Aspergillus spp., Candida spp.
Tinea unguium
Dermatophytic onychomycosis (Dermatophyte infection of the nails)
90% of onychomycosis
Eg: T. Rubrum, T. Interdigitale, T. Tonsurans, E. Floccosum
Local predisposing factors
- nail not isolation
- chronic tinea pedis (Dermatophyte in environment adjacent nail)
- chronic paronychian (Candida spp) = support structures are inflamed, secondary infections
- trauma/ other nail disorders
Host predisposing factors
- poorly controlled DM
- immunosuppression eg: HIV
- peripheral vascular disease = impaired circulation to foot = slower growing thick nails = environment
Environment
- occlusive footwear
- sweating
How do fungi enter the nail?
- Distal/ lateral subungual
— invasion via hyponychium - Superficial white
— direct penetration into dorsal surface of nail plate - Proximal subungual (rare=cuticle protects)
— invasion under proximal nail fold (immunocompromised hosts) - Mixed pattern
— >2 of above patterns in same nail
(Lateral nail fold)
How do fungi affect nails?
- subungual hyperkeratosis (keratin debris under nail plate)
- crumbling
- thickening
- discoloration
- nail plate destruction
(All nail dystrophy)
Nail clippings & sub-ungual debris in lab
- fungal microscopy & culture (/PCR available)
— send nail clippings in saline - histology
— fungal hyphae on formalin-fixed periodic acid schiff (PAS) stained nail clipping
— send nail clippings in formalin
What is paronychia?
- inflammation of nail fold (usually proximal)
- can be divided into acute & chronic forms
Importance of cuticle
- cuticle (eponychium) acts as seal to prevent irritants & pathogens entering beneath proximal nail fold
- seal between proximal nail fold & nail plate
Acute paronychia: mechanism
- Nail biting/ sucking
Manicures
Ingrown toenails
Medications eg: oral retinoids - Minor trauma
- Port of entry for infections
Acute paronychia - pathogens?
- bacterial infection
= staph aureus/ strep pyogenes
Recurrent acute (not always bacterial)
= HSV (“hermetic whitlow”)
Chronic paronychia: mechanism
- Occupations that involve wet work, irritant contact dermatitis of hands
- Disruption of cuticle
- Irritant enter causing inflammation at proximal nailfild
Chronic paronychia- pathogens?
- irritants & not primarily an infection
- secondary infections do occur, Candida eg: candida albicans
Nail dystrophy causes
- infections
- benign/ malignant growths
- cysts
- systemic diseases
Nail dystrophy: asymmetric involvement
- external cause eg: Dermatophyte infection
- if only one nail involved, local problem eg: cyst/ tumor
Nail dystrophy: symmetric involvement
Internal cause eg: systemic diseases
What is clubbing?
- enlargement of soft tissue of digits
— bulbous appearance
— enlarged, curved nail plate
— angle between proximal nail fold & nail plate widened to >180 degrees
Congenital clubbing associated conditions
- cystic fibrosis
- congenital cyanotic heart disease
Acquired clubbing associated conditions
- bronchopulmonary disease
— neoplasms (primary/ metastatic cancers, pleural tumors)
— chronic infections (abscesses of lungs, TB)
—bronchiectasis
— pulmonary fibrosis
— sarcoidosis - CVD eg: bacterial endocarditis
- GITD eg: chronic active hepatitis, IBD
- endocrine disease eg: hyperthyroidism/ Graves’ disease
- other
What is yellow nail syndrome?
- slow nail growth
- nails appear thickened
- increased longitudinal curving
- loss of cuticle
- yellow color
What causes yellow nail syndrome?
Pathophysiology not known
Associated conditions
- chronic lymphedema
- respiratory diseases
— chronic bronchitis
— bronchiectasis
— pleural effusions
Apparement leukonychia
Leuko = white
Nychia = nails
Apparent
- nail plate in not truly white (nail plate is not the issue)
- problem is in the nail bed
- apply pressure to nail, white colour disappears
Eg: Muehrcke’s nails, half & half nails (Lindsay’s nails), terry’s nails
Muehrcke’s nails
- multiple transverse bands parallel to lunula
Associations: - hypoalbuminaemia (nephrotic syndrome, malnutrition, liver disease) mechanism may be oedema of nailbed
- chemotherapy, mechanisms?
Half & half nails
- apparent leukonychia of proximal half of nail
Associations: - normal variant
- chronic renal disease
Mechanism: - uncertain
- nail plate may be loosely attached to nailbed proximally
Terry’s nails
- whole nail white, approx. 2mm band at distal end
Associations: - normal variant
- liver cirrhosis (non-specific)
Mechanism?
Abnormal capillaries in proximal nail fold
Seen in autoimmune connective tissue diseases
- dermatomyositis & systemic sclerosis
- disease damage small capillaries of PNF
May only visible on capillaroscopy/ dermoscopy
Instead of regular capillary loops
- decreased capillary density (dropout, avascular areas)
- giant capillaries
- enlarged/ dilated capillary loops
HIV & the nail
Fungal nail infections
- proximal subungual pattern
- Candida onychomycosis
Longitudinal melanonychia - bands of pigment on nail plate (other causes eg: familial, drug-induced, melanoma, other) not an NB sign of HIV
- HPV-induced SCC
- drug-induced (Zidovudine)
Transverse depressions (Beau’s lines)
- certain insults to nail matrix can cause a temporary arrest in growth of nail plate
= transverse depressions in nail plate, grows out from matrix
Eg of causes: - external trauma to nail matrix eg: manicures, nail biting
- childbirth
- systemic illness
- chemotherapy
- SJS
Generally symmetrical in all nails
Nail shedding (onychomadesis)
- complete cessation of nail plate growth at nail matrix = shedding of nail plate
- causes same as for transverse depressions (Beau’s lines)
- after Cossack is A6 virus infection in children (hand, foot & mouth disease)
Spoon shaped nails (Koilonychia)
Pathogenesis poorly understood
Potential causes eg:
- severe iron deficiency
- amyloidosis
- trauma
- idiopathic
- physiological in 2nd-4th toes of young children (under 5 years old)
Psoriasis & the nail
- clinical presentation depends on what part of the nail is affected by psoriatic inflammation
- matrix(distal & proximal) = pitting
- nail bed = subungual hyperkeratosis
- onycholysis (nail plate separates from nail bed)
- “oil drop” sign (yellow/orange discoloration visible through nail plate
