An Illustration for the students who aspire for medical studies.

a power . presentation from T. MADHAVAN, M. Sc., M.L.I.S., M. Ed., M. Phil., P.G.D.C.A., Lecturer in Zoology.

welcome

` to the session on

Pathology of Skin

PATHOLOGY OF SKIN

Problems to be discussed here are:

Dermatits

Pigmentation

Radiation effects

Dermatitis

It is an inflammation of the skin,

some times forms due to an allergy

in many cases it occurs without any known cause.

many types of the dermatitis are known as eczema.

Apart from eczema the 3 main forms of skin inflammations are:

- photo dermatitis,

- contact dermatitis,

- seborrhoeic dermatitis,

Dermatitis

Contact dermatitis

This type of dermatitis the rash is a reaction to some substances that comes in contact with skin

The reaction may result from a direct toxic effect of the substances or it may be an allergic response.

Contact dermatitis

The more common causes of the reaction results into dermatitis:

- detergents, - nickel (in watch straps, bracelets, necklaces)

- Fastening of underclothes - certain plants (Rag weed)

- certain cosmetics - certain lotions, drops, creams of medication - Allergens

Contact dermatitis

The type of rash varies with the substances causing it.

It is often itchy and may flake or lister.

Distribution of the rash corresponds to the skin area that has been in contact with the causative substance.

Photo dermatitis

This occurs in people whose skin is abnormally sensitive to light.

In the most common form of photo dermatitis a cluster of spots or blisters develop on any part of the body exposed to sun.

An Illustration for the students who aspire for medical studies.

a power . presentation from T. MADHAVAN, M. Sc., M.L.I.S., M. Ed., M. Phil., P.G.D.C.A., Lecturer in Zoology.

Pigmentation

Melanocytes posses the enzyme tyrosinase necessary for the synthesis of melanin from the amino acid called tyrosine.Various disorders of melanin pigmentation cause generalized and localized hyper-pigmentation and hypo-pigmentation.

An Illustration for the students who aspire for medical studies.

a power . presentation from T. MADHAVAN, M. Sc., M.L.I.S., M. Ed., M. Phil., P.G.D.C.A., Lecturer in Zoology.

Pigmentation & MelaninPigmentation & MelaninMelanin is the brown black, Non-Haemoglobin derived pigment normally present in the skin, hair, coroid of eye.

Melanin is synthesised in melanocytes and dendrite cells present in the epidermis.

Melanin is stored as melanophore (in the form of cytplasmic granules in the phagocytic cells ) in the dermis.

The pigmentation problems causes over the skin are due to various disorders of Melanin

An Illustration for the students who aspire for medical studies.

a power . presentation from T. MADHAVAN, M. Sc., M.L.I.S., M. Ed., M. Phil., P.G.D.C.A., Lecturer in Zoology.

An Illustration for the students who aspire for medical studies.

a power . presentation from T. MADHAVAN, M. Sc., M.L.I.S., M. Ed., M. Phil., P.G.D.C.A., Lecturer in Zoology.

Types of Pigmentation

Pigmentation

Hyper Pigmentation

Hypo Pigmentation

Generalized Pigmentation

Generalized Pigmentation

Localized Pigmentation

An Illustration for the students who aspire for medical studies.

a power . presentation from T. MADHAVAN, M. Sc., M.L.I.S., M. Ed., M. Phil., P.G.D.C.A., Lecturer in Zoology.

Generalized Hyper Pigmentation

Addison’s disease: Generalized hyper

pigmentation of the skin especially in areas exposed to

light and buccal mucosa

Chloasma is the hyper pigmentation on skin of

face, Nipples and genitalia during

pregnancy under influence of oestrogen

In Chronic Arsenal Poisoning, there is characteristic rain-drop pigmentation of the skin

An Illustration for the students who aspire for medical studies.

a power . presentation from T. MADHAVAN, M. Sc., M.L.I.S., M. Ed., M. Phil., P.G.D.C.A., Lecturer in Zoology.

Generalized Hypopigmentation

Albinism is an extreme degree of hypo pigmentation which

tyrosinase activity of the melanocytes is generally

defective and no melanin is formed.

Albinose have blonde hair, poor vision and severe photophobia.

Chronic sun exposure may lead to pre-cancerous lesions, squamous and basal

cancers of the skin.

An Illustration for the students who aspire for medical studies.

a power . presentation from T. MADHAVAN, M. Sc., M.L.I.S., M. Ed., M. Phil., P.G.D.C.A., Lecturer in Zoology.

Localized hypopigmentation

Leucoderma is a form of partial albinism and is an inherited disorder

Vitligo is local hypo pigmentation in the skin.

Acquired focal hypo pigmentation can result from causes such as leprosy, healing of wounds, radiation dermatitis, etc.,

The efficiency of UV light as carcinogen depends upon the extent of light- absorbing protective melanin pigmentation of the skin.

The main source of Ultra Violet radiation is the sunlight UV lamps and welder’s

arcs.

UV light penetrates to the skin for a few millimeters only so that its effect is

limited to epidermis.

RADIATION: Solar / UV: effects.

RADIATION: Solar / UV: effects.

In humans excessive exposure to UV rays can cause various forms of skin cancer such as squamous cell carcinoma,

basal cell carcinoma and

malignant melanoma.

Fair skinned people and whites are more prone to skin complications due to UV exposure.

Skin grafting

It is a technic used in plastic surgery to repair areas of lost or damaged skin.

A piece of healthy skin is detached from one part of the

body and transferred to the affected area.

New cells grow from the graft and cover the damaged area with fresh skin.

Skin taken from the identical twin can be used for a graft, but skin from another person or animal is soon rejected by the recipient body

Skin grafting