The hair
The hair (trichos), is epithelial in origin and is made of modified horn cells, and arises in a follicle formed of invaginated epidermal cells, situated in the deeper parts of the dermis. Each hair is made up of the three parts: ?a? an outer layer, named cuticle, made up of flattened horny cells, ?b? the cortex being a thick pigmented layer of spindle shaped cells, ?c? the medulla extending only for a variable distance up the shaft from the papilla, and is made up of a column of nucleated cells (fig.21) .Lanugo hairs have no medulla. A small band of unstriated muscle is encroached to the hair follicle and forms the arrector pili muscle.
Fig.21 Hair bulb. This a complex structure composed of several distinct
layers of structures. The papilla is engorged with blood vessels, and the
germinative cells, which are among the most metabolically active in the
body, lie close by. The hair shaft, which is completely keratinized and
without living cells, lies just to the hair bulb.
There are three types of hair:
1-Lanugo hairs. Fine long hairs covering the fetus, but shed about one month before birth.
2-Vellus hairs. Fine short unmedullated hairs covering much of the body surface. They replace the lanugo hairs just before birth.
3-Terminal hairs. Long coarse medullated hairs, and this subdivided into; [a] scalp hairs, [b] sexual hairs. Sexual hairs developed after puberty [under effect of androgen hormone] on the pubic area and axilla in female, and on the pubic area, axilla, face chest, abdomen and extremities of males. Any disease of pituitary or adrenal glands will affect the distributions of this type of hair.
The hair cycle: Each follicle passes, independently of its neighbors, through regular cycles of growth and shedding. There are three phases of follicular activity (Fig.22).
1-Anagen.The active phase of hair production.
2-Catagen.A short phase of conversion from active growth to the resting phase. Growth stops and the end of the hair become club-shaped.
3-Telogen.A resting phase at the end of which the club hair is shed.
Fig. 22 Phases of the hair cycle. Anagen is the growing portion of the hair cycle, and hairs such as those of the scalp may remain in this phase for many years. At some predetermined time, the hair enters a short-lived interphase (catagen), followed by the resting or telogen phase, in which the hair is shed as a club hair.
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The duration of each of these stages varies from region to region. On the anagen lasts for about 1000days, catagen for about 10days and telogen for about 100days. As many as 100hairs may be shed from the normal scalp every day as a normal consequence of cycling. The proportion of hairs in the growing and resting stages can be estimated by looking at plucked hair (a trichogram), on the scalp, about 85% are normally in anagen and 15% in the telogen phase. The length of hair is determined by the duration of anagen; e.g. the hairs of the eye brows have shorter cycles than those of the scalp. Each hair follicle goes through its growth cycles out of phases with its neighbors, so there is no molting period. However, if many pass into the resting phase (telogen) at the same time, (due to any cause like; fever, haemorrhge, anemia surgery, severs psychological truma, etc) then a corresponding large number will be shed 100days later (this is called telogen effluvium).There are important racial differences in hair. Asians tend to have straight hair, Negroid woolly hair, and Europeans wavy hair. Mongoloids have less facial and body hair than Mediterranean people who also have more hair than Northern Europeans.
Fig. 22 Phases of the hair cycle. Anagen is the growing portion of the hair
Cycle, and hairs such as those of the scalp may remain in this phase for
many years. At some predetermined time, the hair enters a short-lived
interphase (catagen), followed by the resting or telogen phase, in which
the hair is shed as a club hair.
Alopecia: means hair loss .It is divided into localized or generalized and both of the could be classified into non-scarring in which regrowth of hair will occur and scarring in which there is permanent loss of hair due to destruction of hair follicles by many diseases(Box 8 ).
(Box 8).Causes of hair loss (alopecia)
Causes of Localized hair loss:
B- Scarring alopecia:
1- Idiopathic.
2-developmental defect and hereditary
disorders
3-Physical injuries like Burn,
mechanical trauma, Radio dermatitis.
4-Infections like, carbuncle, tinea capitis
(kerion), and herpes zoster.
5-Diseasesof unknown origin like
discoid lups erythematosus
scleroderma, sarcoidosis, necrobiosis 6-cicatricial basal cell carcinoma
7-Pseudopelade.
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A – non-scarring
1-Traumatic alopecia;
(a) Neonatal frictional alopecia
(b) Trichotillomonia
(c) Tractional alopecia
(d) Pressure alopecia
(e) Hot –comb alopecia
2-Alopecia areata
3-Tinea capitis (human origin)
4-Post –pyogenic infection and
secondary syphilis.
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auses of Diffuse hair loss;
causes of Diffuse hair loss;
A- Non – scarring alopecia:-
1- Androgenic alopecia: the loss of hair in both sexes as follows; - In women is fronto - vertical hair thinning and in men is bitemporal and vertical hair thinning.
2- Diffuse type of alopecia areata.
3-Telogen effluvium (fevers, post labor 4-8 months, post major surgery and sever blood loss).
4- Metabolic and endocrine disorders: hypothyroidism, hyperthyroidism, hypoparathyroidism hypopituitraism and diabetes mellitus.
5- Nutritional deficiency, especially iron deficiency.
6-Drugs induced especially antimetablic (anagen effluvium), anticoagulant, excess vit. A., oral contraceptive.7-liver disease.
8- Sever chronic illness. 9 - HIV disease.
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B- Diffuse scarring Alopecia:-
1- Discoid lupus erythematosus
2– Radiotherapy
3-folliculitis decalvans
4 – Lichen planus pilaris
5-Sever extensive burn
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Disorders of the nails
The condition of the nails may reflect both local and systemic disease, and Omission of this part of the general examination could result in some important diagnostic clues being over looked .Fingernails grow about 1 cm every 3 months and toe nails at about one – third of this rate.
Splinter hemorrhage: `these are fine linear dark brown flecks running longitudinally in the plate. They are most commonly to trauma but, they may be seen in psoriasis. They are also sign of bacterial endocarditis, SLE and rheumatoid arthritis. Onycholysis; Onycholysis is painless separation of the nail plate from nail bed (Fig. 23) due to many causes :-( 1) Dermatological disease; psoriasis, dermatitis, dermatophyte or Candidal infection. (2) Trauma (3) General medical conditions; impaired peripheral circulation, hypothyroidism and hyperthyroidism. (4)Hereditary partial onycholysis. (5) Drugs e.g. tetracycline + sunlight exposure.
fig.23 onycholysis
In case of recalcitrant and long lasting onycholysis you should think of:-
1-Post traumatic scar in the nail bed. 2-dermatophyte infection. 3-tumor of the nail bed and especially malignant melanoma (Nail pigment streak and pigmentation of the posterior nail fold (Hutchinson’s sign) is diagnostic of a melanoma affecting the nail matrix, with migration of pigment cells on the posterior nail fold and longitudinal nail biopsy through the streak will confirm the diagnosis).
Beau’s lines: These are transverse grooves which appear at the same time on all nails a few weeks after stress or acute illness that temporarily interrupt nail formation. The lines progress distally with normal nail growth and eventually disappear at free edge.
Spoon nails: Lateral elevation and central depression of the nail plate causes the nail to be spoon shaped; this is called koilonychias (fig. 24). Spoon nails are seen in normal children a and may persist lifetime without any associated abnormalities. It is also a sign of iron deficiency anemia and in 50% of patients with idiopathic hemochromatosis. The nail reverts to normal when the anemia is corrected.
fig. 24 Spoon nail
Finger clubbing: Is a distinct feature associated with a number of diseases, but it may occur as a normal variant .The distal phalanx of fingers and toes are enlarged to a rounded bulbous shape. The nail enlarges and become curved, hard, and thickened. The angle made by the proximal nail fold and plate increase and approaches or exceeds 180 degrees and when both thumb nail put in contact will from open window while in normal it form classed window. Causes of finger clubbing; (1) Respiratory; bronchogenic carcinoma, asbestosis, suppurating lung disease (empyema, bronchiectesis, cystic fibrosis), fibrosing alveolitis. (2)Cardiac; cyanotic congenital heart disease, subacute bacterial endocarditis. (3)Gastrointestinal; ulcerative colitis, crohn’s disease, celiac disease, biliary cirrhosis. (4)Endocrine, thyrotoxicosis (5) Familial.
White spots or bands of the nail (leukonychia punctuate) White spots in the plate are a common finding ,which possibly result from cuticle manipulation or other mild from of trauma . The spots are bands appear at the, unula or appear spontaneously in the nail plate and subsequently disappear or grow out with the nail.
Whitening of the nails Is a rare sign of hypoalbuminoemia, half-and-half nail (white proximally and red – brown distally) are seen in some patients with renal failure. Rarely, drugs (e.g. antimalarials) may discolor nails.
Ingrown toe nail: Ingrown toenail is common; the large toe is most frequently affected, the nail pierces the lateral nail fold and enters the dermis, where it acts as a foreign body .The first signs are pain and swelling .The area of penetration becomes purulent and oedemalous as granulation tissue grows alongside the generating nail. Ingrown nails occur from lateral pressure of poorly fitting shoes, improper or excessive trimming of the lateral nail plate or after trauma.
Differential diagnosis of butterfly erythema on the face :( Fig.25)
1-Discoid lupus erythematosus (DLE). 2-SLE. 3-Psoriasis. 4-Contact dermatitis. 5-Seborrhoeric dermatitis.
6- Lups vulgaris. 7-Necrobiosis lipoidica can give fascail lesions like DLE.
Fig.25 Discoid lupus erythematosus
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المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .