Morphology of The Skin
Fifth class / dermatology3rd / 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 layersEpidermis ( 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 selfb. 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 diameterHas 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 elements1. 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
CrustsExcoriations 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