ï“ 1. ï“ The skin accessory organs, sweat glands, sebaceous glands, hair and the nails largest organ in the human body ï“ The skin together with its accessory

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The Skin

General Methods in preparationof Skin BiopsiesPrepared by:Mr: Mahmoud El-HindiMiss: Afnan Abdelmoneim

1SIntroductionThe skin together with its accessory organs, sweat glands, sebaceous glands, hair and the nails forms the largest organ in the human body.

This system covers 1.5-2m2 and represents 16% of body weight.

The skin and its accessory organs form the integumentary system.


3Layers of the Skin The human skin is composed of three major layers of tissue: epidermis, dermis and subcutaneous layer. The epidermis is the top layer of skin made up of epithelial cells. The dermis is the middle layer of skin, composed of dense irregular connective tissue such as collagen with elastin. The subcutaneous layer is the innermost layer, containing fatty tissue

4EpidermisThe epidermis main functions are protection, absorption of nutrients and homeostasis. Also contains different types of cells: keratinocytes, melanocytes, Merkel cells and Langerhans cells. Accumulations of melanin are packaged in melanosomes. These granules form a pigment shield against UV radiation. It does not contain blood vessels5

6DermisThe dermis is the middle layer of the skin that offers elasticity. It is composed of connective tissues and collagen fibers.

The dermis provides a site for the hair follicles, sweat glands, sebaceous glands, blood vessels, lymph vessels, sensory receptors, nerve fibers and muscle fibers. 7

8Subcutaneous LayerThe subcutaneous is the layer of tissue directly underneath the dermis. It is also called hypodermis.This layer of tissue is composed of fat cells and connective tissue. Its functions include insulation, the storage of energy and aiding in the anchoring of the skin. It is the thickest layer of the integumentary system


10Functions of the SkinProtectionTemperature regulationSensationsStorage of chemical compoundsExcretion of wastesSynthesis of compoundsDetermines characteristics


Stratum corneumStratum lucidumStratum spinosumStratum granulosumStratum basale12overviewCutaneous Pathology (dermatopathology) is the microscopic examination of skin biopsies in order to determine a specific diagnosis or a list of differential diagnoses.

Usually the diagnosis can be determined by the routine stain for tissue sections (Hematoxylin and Eosin).13Skin lesion selectionThe skin lesions which developed recently according to the patient history should be selected for that purpose. Detailed clinical information (age, sex and site of skin biopsy) of the investigated patients should be provided.

Biopsies from healthy donors may be analyzed for control purposes in some cases.14Normal Skin Section15

Common Skin Disorders

16Disorders Fungal InfectionsHyperkeratosis ViralInfectionsSkinInfestations Secondary bacterial infections Canker sores17AcneAcne is a very common skin condition characterized by comedones (blackheads and whiteheads) and pus-filled spots (pustules). It usually starts at puberty and varies in severity from a few spots on the face, back and chest, which most adolescents.



20Basal Cell CarcinomaA basal cell carcinoma (BCC) is a type of skin cancer. There are two main types of skin cancer: melanoma and non-melanoma skin cancer. BCC is a non-melanoma skin cancer, and is the most common type (> 80%) of all skin cancer.



23Contact DermatitisThe words dermatitis and eczema are interchangeable and mean the same thing.Dermatitis means an inflammation of the skin. The term contact dermatitis is used when this inflammation is caused by contact with something in the environment.


25Fungal infection of the nailsFungal infections of the nails are also known as onychomycosis, as tinea unguium, and as ringworm of the nails. The fungi are usually those that cause athletes foot a common infection of the skin of the feet. In athletes foot the fungi live in the keratin that makes up the outer layer of the skin, but they can also invade the hard keratin of which nails are made. When this happens, the result is a fungal infection of a nail.


27MelanomaCutaneous malignant melanoma is a cancer of the pigment cells of the skin. If it is treated early, the outlook is usually good.Melanocytes sometimes grow together in harmless groups or clusters, which are known as moles. Most people have between 10 and 50 moles and often they are darker than the surrounding skin. They can then invade the skin around them and may also spread to other areas such as the lymph nodes, liver and lungs.





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