Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
A مجموعة/ المرحلة الخامسة مازن حامد.د DERMATOLOGY The nails The hard keratin of nail plate is formed in 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 lunule. From this area the nail plate grows forward over the nail bed, ending in a free margin at the tip of the digit. Longitudinal ridges and grooves on the under surface of the nail plate dovetail with similar ones on the upper surface of the nail bed.The nail bed is capable of producing small amounts of keratin which contribute to the nail and which are responsible for the ‘false nail’. 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. They help with fine touch and with the handling of small objects. The rate at which nails grow varies from person to person: finger nails average between 0.5 and 1.2 mm per week, while toe nails 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. Longitudinal ridging and beading are common in the elderly. ►Effects of trauma: Permanent ridges or splits in the nail plate follow damage to the nail matrix. Splinter haemorrhages the linear nature of which is determined by longitudinal ridges and grooves in the nail bed,are mostly seen under the nails of manual workers and are caused by minor trauma, psoriasis and of subacute bacterial endocarditis. Larger subungual haematomas are caused by trauma .Chronic trauma from sport and from ill-fitting shoes contributes to haemorrhage under the nails of big toes, to the gross thickening of toenails known as onychogryphosis and to ingrowing nails. Onycholysis, a separation of the nail plate from the nail bed a result of minor trauma. nail psoriasis and in thyroid disease. The space created colonized by yeasts,or by bacteria such as Pseudomonas aeruginosa, which turns it an ugly green colour. Some nervous habits damage the nails. Bitten nails are short and irregular; some people also bite their cuticles and the skin around nails. Viral warts can be seen. In the common habit tic nail dystrophy, the cuticle of the thumbnail is the target for picking or rubbing. This repetitive trauma causes a ladder pattern of transverse ridges and grooves to run up the centre of the nail plate Lamellar splitting of the distal part of the fingernails in housewives, attributed to repeated wetting and drying .Attempts to beautify nails can lead to contact allergy. Culprits include the acrylate adhesive used with artificial nails and formaldehyde in nail hardeners. contact dermatitis caused by allergens in nail polish seldom affects the fingers but presents as small itchy eczematous areas where the nail plates rest against the skin during sleep. The eyelids, face and neck are favourite sites. ►Systemic disease:The nails can provide useful clues for general physicians. Clubbing is a bulbous enlargement of the terminal phalanx with an increase in the angle between the nail plate and the proximal fold to over180. It occur in chronic lung disease , cyanotic heart disease, familial. The mechanisms un known. Koilonychia, a spooning and thinning of the nail plate, indicates IDA.Colour changes: the ‘half-and- half’ nail, with a white proximal and red or brown distal half in chronic renal failure.Whitening of the nail plates in hypoalbuminaemia,as in cirrhosis of the liver. Some drugs, antimalarials, antibiotics and phenothiazines,can discolour the nails.Beau’s lines are transverse grooves which appear on all nails a few weeks after an acute illness, and which grow steadily to the free margin.Connective tissue disorders: nail fold telangiectasia or erythema in dermatomyositis, systemic sclerosis and SLE. In dermatomyositis the cuticles shaggy, and in systemic sclerosis loss of finger pulp leads to overcurvature of the nail plates.Thin nails, longitudinal ridging and partial onycholysis,are seen if the peripheral circulation is impaired,in Raynaud’s phenomenon.Nail changes in the common dermatoses:Psoriasis Most patients with psoriasis have nail changes; severe nail involvement is more in presence of arthritis.nail pitting of the surface of the nail plate. Almost as common is psoriasis under the nail plate, showing up as red or brown areas, with onycholysis bordered by obvious discoloration.There is no effective treatment for nails psoriasis. Eczema: nails are polished by scratching.,eczema of the nail folds may lead to a coarse irregularity with transverse ridging of the adjacent nail plates. Lichen planus 10% of patients have nail changes.(thinning of the nail plate with irregular longitudinal grooves and ridges , pterygium in which the cuticle grows forward over the base of the nail and attaches itself to the nailplate) /Alopecia areata if severe roughness or fine pitting of nail plates and the lunulae mottled. Infections: Acute paronychia The portal of entry for the organisms( staphylococci), is a break in the skin or cuticle as a result of minor trauma.The acute inflammation,with pus formation in nail fold or under the nail, requires systemic flucloxacillin or erythromycin and surgical drainage. Chronic paronychia a mixture of opportunistic pathogens (yeasts, Gram-+ve cocci and Gram-ve rods) colonize the space between the nail fold and nail plate. Predisposing factors ( poor peripheral circulation, wet work, working with flour, diabetes, vaginal candidosis and over vigorous cutting back of the cuticles.nail folds become tender and swollen, pus discharge. The cuticular seal is damaged and the adjacent nail plate becomes ridged and discoloured. it may last for years. DDX:In atypical cases, consider the outside chance of an amelanotic melanoma.in dermatophyte infection the nail folds are not primarily affected.Investigations Test the urine for sugar, check for vaginal candidosis. Pus should be cultured. Treatment Manicuring of the cuticle should cease. The hands should be kept warm and dry, and the damaged nail folds packed several times a day with an imidazole cream and if swabs confirm candida, a 2-week course of itraconazole . ► Dermatophyte infections The common dermatophytes that cause tinea pedis can invade the nails. Presentation Toenail 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 yellow, crumbly and thickened. Usually only a few nails are infected or all are. The fingernails are involved less often and the changes,in contrast to those of psoriasis, are usually in one hand.it seldom clears spontaneously.DDX Psoriasis.Yeast infections. Coexisting tinea pedis favours dermatophyte infection of nail. IX. Microscopic examination of a nail clipping. Cultures in a mycology laboratory. ►Tumours. Peri-ungual warts are common,stubborn. Cryotherapy must be used carefully to avoid damage to nail matrix. It is painful but effective. Peri-ungual fibromas from nail folds, in childhood, in patients with tuberous sclerosis. Glomus tumours beneath the nail plate.The small red or bluish lesions are exquisitely painful if touched and when the temperature changes. Treatment is surgical.Subungual exostoses protrude painfully under the nail plate secondary to trauma to terminal phalanx, the bony abnormality seen on X-ray and treatment is surgical. Myxoid cysts occur on the proximal nail folds, usually of the fingers. The smooth domed swelling contains a clear jelly-like material transilluminates well. A groove may form on the adjacent nail plate. Cryotherapy, injections of triamcinolone and surgical excision. 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. ► Other abnormalities: congenital nails missing. In the rare nail–patella syndrome, the thumb nails, and to a lesser extent those of the fingers, are smaller than normal. Rudimentary patellae, and renal disease iliac spines complete the syndrome, which is inherited as an AD trait linked with the locus controlling ABO blood groups. Pachyonychia congenita is also rare and inherited as an AD trait. The nails are grossly thickened, and have a curious triangular profile . Hyperkeratosis may occur on areas of friction on the legs and feet. Permanent loss of the nails in the dystrophic types of epidermolysis bullosa. In the yellow nail syndrome the nail changes begin in adult life, against a background of hypoplasia of lymphatic system. Peripheral oedema and pleural effusions may occur.The nails grow very slowly and become thickened and greenish-yellow; their surface is smooth but they are overcurved from side to side. The nail ‘en racquette’ is a short broad nail usually a thumbnail, which is seen in some 1–2% of the population and inherited as AD trait. The basic abnormality is shortness of the terminal phalanx.