Question

a 64-year-old man living in Flagstaff, AZ. He with his dog to play in the back yard. Upon a missed catch by the dog, he ventured towards a stream where the toy landed.  Unfortunately, he took a spill and got a minor cut on his right forearm. He cleaned his wound and covered it with a bandage. A few hours later he noticed that the area around the wound had started to swell. He decided to make a visit to his physician to have it checked out. Initially, he received a triple antibiotic ointment to apply to the superficial skin wounds as well as general cleaning and bandaging of the wound. He was then sent home. The next day, he woke early and experienced continued swelling as well as pain with blistering, warmth to the touch in the area where his forearm was cut, and what appeared to be a spreading red rash. He also was experiencing a fever of 101.1 F immediately made another appointment with his physician to address the issue.

1. Which layers of tissue in the skin may be damaged from a cut or scrape on the surface of the body? Describe the specific layers that may be involved.
2. What are the functions of the skin as it pertains to the immune system? Explain.
3. What is a differential diagnosis?
4. Research his symptoms and determine a differential diagnosis by listing at least two different possible conditions that match some or all of his symptoms. Justify why you selected each of the conditions on your list.
5. Explain the distinction between signs and symptoms. What are his signs and symptoms?
6. If you were his physician what tests might you perform in order to find signs related to his condition to help you determine a diagnosis? List and describe two specific clinical tests that might provide helpful information.

Answer 1

• ANSWER 1
• layers of tissue in the skin may be damaged from a cut or scrape is epidermis has been
• Thin-skinned bony areas (like knees, ankles and elbows) are more prone to abrasions than thicker, more padded areas.
• The scraped skin of an abrasion can contain particles of dirt

ANSWER 2

SPECIFIC LAYER OF SKIN INVOLVED

The epidermis ( the surface layer) AND several sheets of skin cells. The dermis lies underneath and consists of elastic fibres (elastin), and protein fibres (collagen) for strength. Sebaceous glands, hair follicles, nerves and blood vessels are found in the dermis

answer 3 SKIN AS IMMUNE SYSTEM

The skin ACT AS immune system that protects the body from

• infection,
• cancer,
• toxins,
• attempts to prevent autoimmunity,
• physical barrier against the external environment.

immune system of skin is called skin-associated lymphoid tissue (SALT)

skin has both type of specific and non specific immunity

.1. INNATE IMMUNITY - IMMEDIATE AND NOT BASED ON IMMUNOLOGICAL MEMORY

Keratinocyte

• predominant cells in the epidermis.
• first line of innate immune defence against infection.
• express Toll-like receptors (TLRs), trigger an inflammatory response.
• Keratinocytes communicate with the rest of the immune system through interleukin, cytokines

Macrophages and neutrophils

• Macrophages are phagocytic cells discriminate between the body's cells (self) and foreign molecules. After phagocytosis by macrophages, an invading pathogen is killed inside the cell.
• Activated macrophages recruit neutrophils to enter the circulation and travel to sites of infection or inflammation.
• Neutrophils are the first cells to respond to infection. They directly attack microorganisms by phagocytosis and by degranulation of toxic substances.

Dendritic cells

During the innate response:

• Dendritic cells possess TLRs that can be activated by microbial components
• Plasmacytoid dendritic cells (pDCs) produce large amounts of interferon-γ (IFN-γ) in response to viral infection.

Natural killer cells

NK cells are cytotoxic lymphocytes that can eliminate virally infected cells and cancer cells without antigen presentation or priming.

Mast cells

Mast cells are activated in response to allergic reactions and produce cytoplasmic granules filled with pre-formed inflammatory mediators, such as histamines.

These mediators can result in pruritic weals due to increased vascular permeability (urticaria).

Eosinophils

Eosinophils enter the skin in pathological conditions such as parasitic infestations and atopic dermatitis

it release cytoplasmic cytotoxic granules to kill the parasite.

Complement system

The complement system is an enzymatic cascade of over 20 different proteins normally found in the blood. When an infection is present, the system is sequentially activated leading to events that help destroy the invading organism.

adaptive(specific immunity)

Based on memory,

require production of specific T-lymphocytes and B-cell

Dendritic cells , or antigen–presenting cells identify antigens and present them to immature T cells. Epidermal Langerhans cells use their dendrites (arm-like projections) to survey the environment, especially in the stratum corneum. The Langerhans cells bind pathogens to their TLRs, travel to draining lymph nodes, and present antigens to naïve lymphocytes

two major histocompatibility complex occur

• MHC-I is found on all cells in the body and is used to display endogenous substances, such as viral or tumour proteins.
• MHC-II is found on APCs (dendritic cells, monocytes/macrophages and B cells) and is used to display foreign non-self molecules.

T cells

The skin contains resident T cells and recruits circulating T cells.

unable to recognise pathogens directly.

The receptor on the surface of a T cell binds to the peptide on the surface.

Effective antigen presentation allows for naïve T cells to mature into effector T cells, which in turn differentiate into two varieties: cytotoxic CD8+ T cells and CD4+ T helper (Th) cells.

Cytotoxic CD8+ T cells recognise and bind to MHC-I molecules.

CD4+ Th cells recognise and bind to MHC-II molecules. reign and self-antigens and prevent autoimmunity reactions.

B cells

create a memory of prior antigen exposure to ensure a faster immune response and a lasting immunity.

B cells produce antibodies (immunoglobulins) that can bind to specific antigens. Antibody effector functions are:

• Neutralisation — antibodies binds to the pathogen and prevents adherence/infection
• Opsonisation — the coating of the antigen surface by antibodies and the subsequent uptake by phagocytic cells
• Complement activation.

answer 4

differential diagnosis of cellulitis

1. stasis dermatitis- inflammation of skin due to poor blood flow
2. lyme disease -  characteristic bullseye rash( central or ring like)

• Factors supportive of Lyme include recent outdoor activities
• Lyme can also result in long-term neurologic complications.

ANSWER 5

SYMPTOMS OF CELLULITIS

• tight, glossy, swollen skin
• pain and tenderness in the affected area
• redness or inflammation of your skin
• a skin sore
• a feeling of warmth in the affected area( INCREASe in temp)
• an abscess with pus
• fever

More serious cellulitis symptoms include:

• shaking
• chills
• feeling ill
• fatigue
• dizziness
• lightheadedness
• muscle aches
• warm skin
• sweating

answer investigation needded

clinical feature

• swelling of the skin
• redness and warmth of the affected area
• swollen glands

complete blood test and bacterial culutre