Morphology of The Skin

Morphology of The Skin

Fifth class / dermatology
3rd / November/ 2016
Lec. 1
DR. MANAR GHANEM
M.B.CH.B. F.I.C.M.S.

Structure of the skin

The skin compose of three layers
Epidermis ( cells only )
Dermis ( connective tissue , blood vessels and nerves
Subcutaneous layer : fatty layer protect the body from heat and mechanical trauma

Skin Layers

Histology of The Skin

a. Primary lesions: (original lesions ) produced by the disease it self


b. Secondary Lesions: the primary lesions continue to develop or may be regress, or if it is subjected to trauma , or due to the effect of itching , infection , or to the effect of treatment

Macules

Circumscribed discoloration of the skin without elevation or depression of less than 1 cm in diameter
Has a flat surface
E.g. vitiligo , freckles

Patch : If the discolaration is larger than 1 cm.

Papule “Pimple”

Are circumscribed, solid elevations of skin of less than 1 cm in the skin .
E.G. Acne , warts
Palque :
if it is more than 1 cm or confluences of papules, then it is called plaque .

Nodule “small knot”

Similar to papule but it has two elements
1. Depth.
2. Elevation of the epidermis
e.g. : acne , leishmania


Tumors
Soft or firm
Freely movable or fixed masses
of various sizes and shape.
“A tumor is an abnormal mass of tissue, the growth of which exceeds and un-coordinated with normal tissue and persists in the same excessive manner after cessation of stimulus which evoked the change”.

Cyst

a cyst is a cavity containing liquid or semi-solid material may be superficial or deep.

Wheal

Circumscribed edematous papule with erythematous boarder and pale center , could be of various size .

It is evanescent ( transient ) takes few hours and fade-away

It is characteristic lesion of urticaria







Vesicles “Little bladder” : are circumscribed epidermal elevations less than 1 cm in size and containing clear fluid.

Bullae ” Bubble ”: are circumscribed or irregularly shaped cavity more than 1 cm in diameter containing clear , serous or seropurulent fluid.







Pustule (Pustula-Pus): circumscribed accumulation of pus in the skin of less than 1 cm in diamter .

Abscess : circumscribed accumulation of pus in the skin of larger than 1 cm in diamter

B. Secondary Lesions: the primary lesions continue to develop or may be regress, or if it is subjected to trauma , or due to the effect of itching , infection , or to the effect of treatment

Scales

Crusts
Excoriations and abrasions
Fissures
Erosions
Ulcers
Scars
Keloid
Atrophy
Lichenification

Scales: are sheets of dead keratinocyte accumulated together , dry or greasy laminated masses of keratin accumulated together before shedding

Excoriations : an excoriation is a punctate or linear abrasion produced by mechanical means usually involving only the epidermis and rarely reaching the papillary layer of the dermis .


Erosions: loss of all or portion of epidermis alone, heal without scar .
Fissures : is a linear cleft or crack through the epidermis or rarely into the dermis caused by disease (eczema ) or injury.

Ulcers loss of epidermis and part of the dermis, heal with scar .

Crusts are dried serum, pus or blood, usually mixed with epithelial and bacterial debris, on the surface of the skin .

Scars accumulation of fibrous tissue in the dermis or deeper parts as a result of injury or disease, as a part of the normal healing process , scar may be hypertrophic or atrophic

Keloid (claw like ) is a firm, irregularly shaped, thickened, hypertrophic, fibrous, pink or red excrescence.

Lichenification : thickening of the skin with increase skin marke and hyperpigmentation , as in chronic eczema

KELOID

LICHENIFICATION

THANK YOU

Next lecture:
Psoriasis
Other papulosequamous disease