Morphology of The Skin

Fifth stage

Dermatology
Lec-1
د.منار

3/11/2016

MORPHOLOGY OF SKIN LESIONS
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

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

Macule,
patch
Papule,
plaque,
nodule,
tumor
cyst
Wheals
Vesicle
Bullae
Pustule

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
Ulcers
Excoriations
Erosions
Fissures
Scars-hypertrophic scars
Keloid
Lichenification
Primary lesions



Mucule: spot
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- (Latin Paula, “Pimple”)
Are circumscribed,
solid elevations of skin
of less than 1 cm in the skin .
E.G. Acne , warts

Plaques: (French- Plaque- “Plate”)

if it is more than 1 cm or confluences of papules

Nodules" 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.

Wheals (Hives) wheals

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

Secondary Lesions

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