Dermatology & burns

By

Dr. Mohsen Dashti

Clinical Medicine & Pathology 316 4th Lecture

Lecture outline

• Review of structure & function.

• Most frequent & serious problems.

• Symptoms, sings & tests.

• Specific diseases.

• Organ failure.

Review of structure & function • What is the main structure of the skin?

- Squamous epithelium (epidermis – outer covering) & fibrous connective tissue (dermis – underlying layer).

- What lies beneath the dermis?

- Hair follicles, sweat glands, blood vessels, sensory nerves, and deep layer of subcutaneous tissue.

• What are the functions of the skin?

1. Barrier between the body & its external environment.

2. Protect the body from injury by external forces.

3. Prevent excessive loss of body fluids.

4. Constitute major sense organ; sensation of touch, temperature, pressure, and pain.

5. Control the amount of blood brought near the surface for heat exchange trough the process of sweating.

6. Provide resistance to mechanical force, allowing the skin to return to its normal form after mechanical deformation.

Review of structure & function

• Review for the review… • The skin is one of the largest organs in the body in surface area and

weight. The skin consists of two layers: the epidermis and the dermis. Beneath the dermis lies the hypodermis or subcutaneous fatty tissue. The skin has three main functions: protection, regulation & sensation.

• The skin is an organ of protection. The primary function of the skin is to act as a barrier. The skin provides protection from: mechanical impacts and pressure, variations in temperature, micro-organisms, radiation and chemicals.

• The skin is an organ of regulation. The skin regulates several aspects of physiology, including: body temperature via sweat and hair, and changes in peripheral circulation and fluid balance via sweat.

• The skin is an organ of sensation. The skin contains an extensive network of nerve cells that detect and relay changes in the environment. There are separate receptors for heat, cold, touch, and pain. Damage to these nerve cells is known as neuropathy, which results in a loss of sensation in the affected areas. Patients with neuropathy may not feel pain when they suffer injury, increasing the risk of severe wounding or the worsening of an existing wound.

Review of structure & function

Review of structure & function

Most frequent & serious problems • What are the most common dermatologic

problems?

- Cuts, moles, eczematous dermatitis, rashes of various types, lesions, skin cancer… etc.

- What are the life-threatening conditions of the skin?

- Extensive burns, severe drug reactions, malignant melanomas, and loss or destruction of large areas of epidermis.

1. Acne…

- An inflammatory disease of the sebaceous glands, characterized by pimples, especially on the face, back, and chest, and in severe cases, by cysts and nodules resulting in scarring.

Most frequent & serious problems

2. Melasma…

- Dark pigmentation (coloration) of the skin.

Most frequent & serious problems

3. Rosacea…

- A chronic form of acne affecting the nose, forehead, and cheeks, characterized by red pustular lesions.

Most frequent & serious problems

4. Dermatitis…

- Inflammation of the skin.

Most frequent & serious problems

5. Psoriasis…

- A common chronic, inflammatory skin disease characterized by scaly patches.

Most frequent & serious problems

Most frequent & serious problems

Symptoms, signs & tests • Are skin diseases life threatening? - Most skin diseases are not life threatening, but many are

distressing to patients because of unsightly appearance, itching and pain. Compared to other body systems, are they visible?

- Yes off course.

- What are the most common signs of skin diseases?

1. The gross appearance of the lesions.

2. The history of their development.

- The gross appearance include; size, location on the body, multiplicity, color, shape, and texture.

- Rashes are the most common skin diseases and include, measles, rubella and chicken pox.

- Tests include biopsy and laboratory tests.

• The gross appearance of skin lesions follow particular patterns:

a. Macule: change in skin color; not raised or depressed.

b. Nodule: knot or lump; elevated solid lesion.

c. Papule: very small lump.

d. Pustule: elevated skin lesion containing pus (yellow-white substance consisting of liquid plasma).

e. Blister: bubble-like swelling containing air or fluid.

f. Hive: ridge-like reddened elevation caused by edema and congestion.

g. Scale: flaky superficial material (keratin) that easily separates from the skin.

h. Crust: hardened, adherent serum on skin surface over a lesion.

Symptoms, signs & tests

Symptoms, signs & tests

Macule: skin color Nodule: elevated solid lesion

Papule: very small lump Pustule: elevated skin lesion with pus

Symptoms, signs & tests

Blister: bubble-like with air or fluid Hive: ridge-like reddened elevation

Scale: flaky superficial keratin Crust: hardened adherent serum

Specific diseases 1. Genetic/developmental diseases:

a. Hemangioma:

- Proliferations of small blood vessels in the dermis present as elevated red or purple lesions.

- They increase slowly in size, and if involved in one side of the forehead, may be associated with vascular lesions in the brain, seizure disorders and mental retardation.

b. Hair disorders:

- The distribution, color, and texture of scalp and body hair are genetically determined and influenced by hormones. Examples?

- Excessive body hair (hirsutism – in females) and early onset of baldness (alopecia – in males) are the two most common genetic diseases of the skin.

Specific diseases

2. Inflammatory/degenerative diseases:

a. Verruca (Warts):

- It occurs on exposed body parts, particularly the fingers and back of the hand, and is raised dry lesion.

- They can be very painful depending on their location especially around the palms & soles.

- They are very common with children.

Specific diseases

b. Impetigo:

- A superficial bacterial skin infection that occurs predominantly in children and is characterized by crusty blisters and pustules usually on the face.

Specific diseases

3. Hyperplastice/Neoplastic diseases:

- The skin is the most common site of neoplastic & preneoplastic change. Why?

- Long exposure to sunlight in association with aging is important in the vast majority of these lesions.

- The skin is exposed to a number of benign and malignant tumors.

-- Review the previous lectures on neoplasia for more information.

Specific diseases

Organ failure • Other than severe malignant tumors, what

condition can cause organ failure?

- SEVERE BURNS.

- As discussed previously the skin is an organ of …., …., ….?

- Organ of protection, regulation, and sensation.

- The skin has an important role to play in the fluid and temperature regulation of the body. If enough skin area is injured, the ability to maintain that control can be lost.

- If large amount of the skin is damaged these functionality will be lost and with it the entire organ could fail.

- The amount of damage that a burn can cause depends upon its location, its depth, and how much body surface area that it involves.

• How are burns classified?

- Burns are classified based upon their depth.

- What are the classifications of burns?

1. A first degree burn is superficial and causes local inflammation of the skin. Sunburns often are categorized as first degree burns. The inflammation is characterized by pain, redness, and a mild amount of swelling. The skin may be very tender to touch.

2. Second degree burns are deeper and in addition to the pain, redness and inflammation, there is also blistering of the skin.

3. Third degree burns are deeper still, involving all layers of the skin, in effect killing that area of skin. Because the nerves and blood vessels are damaged, third degree burns appear white and leathery and tend to be relatively painless.

Organ failure

• Are burns static?

- Burns are not static and may mature. Over a few hours a first degree burn may involve deeper structures and become second degree.

- Regardless of the type of burn, inflammation and fluid accumulation in and around the wound occur. Moreover, it should be noted that the skin is the body's first defense against infection by microorganisms. A burn is also a break in the skin, and the risk of infection exists both at the site of the injury and potentially throughout the body.

- Only the epidermis has the ability to regenerate itself. Burns that extend deeper may cause permanent injury and scarring and not allow the skin in that area to return to normal function.

Organ failure

• How do we classify burns based on degrees?

- In addition to the depth of the burn, the total area of the burn is significant. Burns are measured as a percentage of total body area affected, and the "rule of nines" is often used.

Organ failure

• How important is the location of burn?

- Burn location is an important consideration. Why?

- If the burn involves the face, nose, mouth or neck, there is a risk that there will be enough inflammation and swelling to obstruct the airway and cause breathing problems.

- If there are burns to the chest, as the burn progresses, the tissue involved may not allow enough motion of the chest wall to allow adequate breathing to occur. If burns occur to arms, legs, fingers, or toes, the same constriction may not allow blood flow and put the survival of the extremity at risk.

Organ failure

Organ failure

It’s finally over…