This is just a concise guide about identifying various disorders affecting the nails.....
Hope its useful.
Anatomy of the Nail
Nails are KERATIN produced by a modified form of epidermis called NAIL MATRIX. Keratin is a protein complex which gives the nail its hard property. The NAIL PLATE grows from the nail matrix and this lies on the nail bed.
Functions of Nails
1. They protect the end of the digits.
2. In the fingers they are useful for picking up small objects and for scratching
ABNORMALITIES OF NAIL MATRIX
When an inflammatory condition affects the nail matrix areas of abnormal keratin are formed.This abnormal keratin detaches itself from the nail plate leaving behind Pits or Ridges.
It is more easily seen on Finger nails.
a. Isolated pits in Normal nails
b. Psoriasis small regular pits
c. Eczema large and irregular pits with associated eczema around the nails.
d. Alopecia areata small regular pits (If a patient with alopecia areata has pitting it is a poor prognosis for hair regrowth)
2. TRANSVERSE RIDGES
b. Chronic paronychia this is mainly due to pressure on the nail matrix.
c. Beaus lines
Beaus line is a single line usually at the same place in all the nails. This is due to cessation of growth of nail matrix at the time of severe illness. After the illness, the matrix functions normally and the nail continues growing with a line in it.
3. LONGITUDINAL RIDGES
Causes when a single nail is affected:
a. Median nail dystrophy
It is temporary and resolves spontaneously after a few months. Cause is unknown. It looks like a upside down Christmas tree in the centre of the nail.
b. Habit tic deformity
This is a broader ridge with numerous concave transverse ridges. It is mainly caused due to picking or biting the nail.
c. Ridge due to underlying myxoid cyst or wart in the posterior nail fold which presses on the underlying nail matrix.
Causes when all nails are affected:
a. Few ridges can be seen in Normal nails.
b. Lichen planus fine and regular
c. Dariers disease fine and regular with notching of the end of the nail.
ABNORMALITIES OF THE NAIL BED
The nail bed is the area of epidermis situated under the nail which does not produce any keratin. Any abnormality in the nail bed causes discolouration under the nail
1. Orange brown colour - Psoriasis (Salmon Patches)
2. Red/purple/black colour
a. Splinter haemorrhage small red longitudinal streaks seen in Sub acute bacterial endocarditis.
b. Sub ungual haematoma due to bleeding under the nail following trauma. It is very painful
c. Sub ungual malignant melanoma
3. Brown colour
a. Junctional naevus
b. Malignant melanoma
4. Pink colour
a. Glomus tumour benign tumour presenting as tender area under nail
5. White colour
Pallor of nail bed occurs in
b. Chronic renal failure
ABNORMALITIES OF NAIL PLATE
A. Discolouration of the nail plate
1. External staining nicotine, medicines, hair dyes, nail varnish
a. Chloroquine Blue grey pigmentation
b. Penicillamine yellow
3. White nails
a. White streaks due to minor trauma
b. Familial leuconychia autosomal dominant whole nail is white
c. Onycholysis distal end of nail plate is broken off
4. Brown lines in nails
a. Junctional naevus
b. Malignant melanoma
5. White/ Yellow nails
a. Tinea irregular thickened area
6. Yellow nail syndrome
a. All nails are yellow/green
b. Excessively curved
c. Rate of growth decreased can cause onycholysis
d. Due to congenital abnormality of the lymphatics
e. Maybe associated with Lymphoedema of legs or Bilateral pleural effusion
B. Thickening of the nail plate
Dermatophyte fungi live on keratin and so actively multiply in the nail plate causing thickened and discoloured nails. It mainly affects toe nails.
Look for evidence of fungal infection in between toes and confirm by nail clippings.
b. Chronic trauma mainly toe nails
ABNORMALITIES OF THE HYPONYCHIUM
This means the separation of the nail plate from the nail bed. This is due to abnormality of hyponychium cos the nail plate is not firmly stuck onto the nail bed.
1. Trauma during manicure, excessive wetting, sub ungula haematoma
3. Fungal infection
4. Poor peripheral circulation
6. Allergic contact dermatitis
ABNORMALITIES OF THE CUTICLE
The cuticle joins the posterior nail fold to the nail plate and thus prevents bacteria from getting into the area around the nail.
If the cuticle is lost, infection can occur under the lateral or posterior nail fold causing PARONYCHIA.
1. Acute Paronychia
This is caused by infection with Staphylococcus aureus. It is associated with pain, redness, swelling and pus formation.
2. Chronic Paronychia
This is usually caused by Candida albicans and is more chronic. It has less swelling, no pus, and may have secondary infection.
ABNORMAL SHAPES OF NAILS
1. Over curvature
c. Yellow nail syndrome
2. Spoon shaped nails (Koilonychia)
a. Iron deficiency anaemia
b. Normal in small children
3. Wedge shaped nails
a. Pachyonychia congenita
It is a rare genetic abnormality. In this condition nail grows vertically and horizontally resulting in a wedge shaped nail.
4. Ingrowing toenails
When the nail penetrates the lateral nail fold it can cause redness, pain, pus and granulation tissue
LOSS OF NAILS
1. Temporary (without scarring)
b. Beaus lines may break after severe illness
2. Permanent (with scarring)
a. Lichen planus cuticle grows through the nail plate resulting in scarring. This change is called Pterygium
OTHER CONDITIONS SEEN AROUND NAILS
1. Viral warts
2. Myxoid cysts
3. Subungual and periungual fibromas
4. Subungual exostosis
5. Tumours squamous cell carcinoma, malignant melanoma
NAIL CHANGES ASSOCIATED WITH SKIN DISORDERS
Onycholysis, Nail pitting, Hyperkeratosis, Pustule and maybe occasional loss of nail.
Discolouration, Onycholysis and thickening of the nail
Usually due to Staphylococcal and Pseudomonas infections may give discolouration to the nails, paronychia.
4. Lichen Planus
Thinning of nail plate, Longitudinal ridges, pterygium
5. Alopecia areata
Pitting, thickening and ridging of nail (Sandpaper nail)
Coarse pits, Ridging, Onycholysis
NAIL CHANGES ASSOCIATED WITH SYSTEMIC DISEASES
Iron deficiency anaemia
2. Yellow nail syndrome
Recurrent pleural effusions, Chronic bronchitis, Bronchiectasis, Nephrotic syndrome, Hypothyroidism
3. Nail-patella syndrome
There is loss of ulnar half of the nails and it usually affects the thumb nail.
It is associated with small patellae, bony spines over posterior iliac crest, renal abnormalities, over extension of joints and skin laxity.
4. Beaus lines
This occurs following a systemic illness
5. Half and Half nails
In this condition the proximal nail bed is WHITE and the distal is PINK or BROWN. This is associated with Chronic renal failure and Rheumatoid arthritis.