dermatology 5th year, 2nd lecture (dr. darseem)
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The lecture has been given on Nov. 28th, 2010 by Dr. Darseem.TRANSCRIPT
Diseases of the Diseases of the nailsnails
The hard keratin of the nail plate is formed in the nail matrix, which lies in an invagination of the epidermis (the nail fold) on the back of the terminal phalanx of each digit .
The matrix runs from the proximal end of the floor of the nail fold to the distal margin of the lunule .
From this area the nail plate grows forward over the nail bed, ending in a free margin at the tip of the digit .
The nail bed is capable of producing small amounts of keratin which contribute to the nail and which are responsible for the ‘false nail’ formed when the nail matrix is obliterated by surgery or injury .
The cuticle acts as a seal to protect the potential space of the nail fold from chemicals and from infection .
The nails provide strength and protection for the terminal phalanx. Their presence helps with fine touch and with the handling of small objects.
The rate at which nails grow varies from person to person: fingernails average between 0.5 and 1.2 mm per week, while toenails grow more slowly.
Nails grow faster in the summer, if they are bitten, and in youth.
They change with ageing from the thin, occasionally spooned nails of early childhood to the duller, paler and more opaque nails of the very old .
A. Trauma:A. Trauma:*Permanent ridges or splits in the nail plate can follow*Permanent ridges or splits in the nail plate can followdamage to the nail matrix.damage to the nail matrix. *Splinter haemorrhages, the linear nature of which is *Splinter haemorrhages, the linear nature of which is determined by longitudinal ridges and grooves in the determined by longitudinal ridges and grooves in the nail bed, are caused by: nail bed, are caused by: -minor trauma-minor trauma-psoriasis of the nail -psoriasis of the nail -subacute bacterial endocarditis.-subacute bacterial endocarditis.
*Larger subungual haematomas are usually easy to *Larger subungual haematomas are usually easy to identify but the trauma that caused them may have identify but the trauma that caused them may have escaped notice and dark areas of altered blood can raise escaped notice and dark areas of altered blood can raise worries about the presence of a subungual melanomaworries about the presence of a subungual melanoma..
**Chronic trauma from sport and from ill-fitting shoes Chronic trauma from sport and from ill-fitting shoes contributes to haemorrhage under the nails of the big contributes to haemorrhage under the nails of the big toes, to the gross thickening of toenails known as toes, to the gross thickening of toenails known as onychogryphosisonychogryphosis and to ingrowing nails. and to ingrowing nails.
*Onycholysis*Onycholysis, a separation of the nail plate from the, a separation of the nail plate from thenail bed may be a result of nail bed may be a result of -minor trauma-minor trauma-nail psoriasis -nail psoriasis -thyroid disease.-thyroid disease. Usually no cause for it is found. Usually no cause for it is found. The space created may be colonized by yeasts, or by The space created may be colonized by yeasts, or by bacteria such as bacteria such as Pseudomonas aeruginosaPseudomonas aeruginosa, which turns , which turns it an ugly green colourit an ugly green colour..
B. Nail in systemic disease:B. Nail in systemic disease:1. Koilonychia:1. Koilonychia: a spooning and thinning of the nail plate, indicates iron a spooning and thinning of the nail plate, indicates iron deficiency.deficiency.
2.Colour changes2.Colour changes:: -the ‘half-and-half’ nail, with a white proximal and red or -the ‘half-and-half’ nail, with a white proximal and red or brown distal half, is seen in patients with chronic renal brown distal half, is seen in patients with chronic renal failure.failure.-Whitening of the nail plates may be related to hypo--Whitening of the nail plates may be related to hypo-albuminaemia, as in cirrhosis of the liver.albuminaemia, as in cirrhosis of the liver.-Some drugs, notably antimalarials, antibiotics and -Some drugs, notably antimalarials, antibiotics and phenothiazines, can discolor the nailsphenothiazines, can discolor the nails..
3 .Beau’s lines: transverse grooves which appear synchronously on all nails a
few weeks after an acute illness.
4 .Connective tissue disorders: nail fold telangiectasia orerythema is a useful physical sign in dermatomyositis,systemic sclerosis and systemic lupus erythematosus.
In dermatomyositis the cuticles become shaggy. In systemic sclerosis loss of finger pulp leads to overcurvature
of the nail plates .
C. Nail changes in the common dermatoses:
1 .Psoriasis The best-known nail change are:
Pitting of the surface of the nail plateOnycholysis DiscolorationSplinter hemorrhageSubangual hyperkeratosisThere is no effective treatment for psoriasis of the nails.
2 .EczemaSome patients with itchy chronic eczema bring theirnails to a high state of polish by scratching .
In addition, eczema of the nail folds may lead to a coarseirregularity with transverse ridging of the adjacentnail plates.
3 .Lichen planusSome 10% of patients with lichen planus have nail changes .
Most often this is a reversible thinning of the nail plate with irregular longitudinal grooves and ridges .
More severe involvement may lead to pterygium in which the cuticle grows forward over the base of the nail and attaches itself to the nail plate
4 .Alopecia areataThe more severe the hair loss, the more likely there isto be nail involvement .
A roughness or fine pitting is seen on the surface of the nail plates and the lunulae may appear mottled.
D. Infections:
1.Acute paronychiaThe portal of entry for the organisms, usually staphylococci, is a break in the skin or cuticle as a result of minor trauma .
There will be acute inflammation, often with the formationof pus in the nail fold or under the nail.Treatment is with flucloxacillin or erythromycin and appropriate surgical drainage.
2 .Chronic paronychiaCauseA mixture of pathogens (yeasts, Gram-positive cocci and Gram-negative rods) colonize the space between the nail fold and nail plate .
Predisposing factors include a poor peripheral circulation, wet work, working with flour, diabetes, vaginal candidosis and overvigorous cutting back of the cuticles.
Presentation and courseThe nail folds become tender and swollen and small amounts of pus are discharged at intervals. The cuticule is damaged and the adjacent nail plate becomes ridged and discolored.
The condition may last for years.
Differential diagnosis-amelanotic melanoma .-dermatophyte infection.
TreatmentManicuring of the cuticle should cease .The hands should be kept as warm and dry .
The damaged nail folds packed several times a day with animidazole cream .
If there is no response, and swabs confirm that candida is present, a 2-week course of itraconazole should be considered.Treat gram negative rods and gram positive cocci .
3 .Dermatophyte infectionsCauseThe common dermatophytes that cause tinea pedis
can also invade the nails include ;Trichophyton rubrum Trichophyton mentagrophytes var.interdigitale and Epidermophyton floccosum
PresentationToe nail infection is common and associated with tinea pedis .
The early changes occur at the free edge of the nail and spread proximally .
The nail plate becomes yellow, crumbly and thickened. Usually only a few nails are infected but occasionally all are. The finger nails are involved less often and the changes, in contrast to those of psoriasis, are usually confined to one hand.
Clinical courseThe condition seldom clears spontaneously.
Differential diagnosisPsoriasis .
Yeast infections of the nail plate, much more rare than dermatophyte infections, can look similar .Coexisting tinea pedis favours dermatophyte infection of the nail.
InvestigationsMicroscopic examination of a nail clipping .Cultures should be carried out in a mycology laboratory.
Treatment Localimidazole preparations (e.g. miconazole and clotrimazole) ,allylamines such as terbinafine ,
benzoic acid ointment (Whitfield’s ointment),and tolnaftate. They should be applied twice daily .
Topical nail preparations Nail lacquer containing amorolfine. It should be applied once or twice a week for 6 months,Amorolfine and tioconazole nail solutions .They can be used as adjuncts to systemic therapy.
Systemic rherapy terbinafine, griseofulvin, itraconazole and fluconazole .
E. Tumours1 .Peri-ungual warts
Are common and stubborn .Cryotherapy must be used carefully to avoid damage tothe nail matrix. It is painful but effective.
2 .Peri-ungual fibromas Arise from the nail folds, usually in late childhood, in patients with tuberous sclerosis.
3 .Glomus tumours Can occur beneath the nail plate.The small red or bluish lesions are exquisitely painfulif touched and when the temperature changes .Treatment is surgical.
4 .Subungual exostoses Protrude painfully under the nail plate .Usually secondary to trauma to the terminal phalanx .
The bony abnormality can be seen on X-ray and treatment is surgical.
5 .Myxoid cysts Occur on the proximal nail folds, usually of the fingers .
The smooth domed swelling contains a clear jelly-like material that transilluminates well .
Cryotherapy, injections of triamcinolone and surgical excision all have their advocates.
6 .Malignant melanoma should be suspected in any subungual pigmented lesion, particularly if the pigment spreads to the surrounding skin. Subungual haematomas may cause confusion but ‘grow out’ with the nail .
The risk of misdiagnosis is highest with an amelanotic melanoma, which may mimic chronic paronychia or a pyogenic granuloma.
F. Some other nail abnormalitie:
1 .Pachyonychia congenita Rare and inherited as an autosomal dominant trait .
The nails are grossly thickened, especially peripherally. Hyperkeratosis may occur on areas of friction on the legs and feet.
2 .Nail–patella syndromeInherited as an autosomal dominant trait .
The thumbnails, and to a lesser extent those of the fingers, are smaller than normal .
Rudimentary patellae, and renal disease complete the syndrome .
3 .yellow nail syndrome The nail changes begin in adult life, against a background of hypoplasia of the lymphatic system .
Peripheral edema is usually present and pleural effusions may occur.The nails grow very slowly and become thickened andgreenish-yellow; their surface is smooth but they areovercurved from side to side.
4 .The nail ‘en racquette’is a short broad nail usually a thumbnail, which is seen insome 1–2% of the population and inherited as an autosomal dominant trait .
The basic abnormality is shortness of the underlying terminal phalanx.
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