Week 1 Dermatology Formative Questions

Question 1

Which layer are the following associated with? Highly metabolically active small cuboidal cells Odland bodies Corneocytes Polyhedral cells with lots of desmosomes

Answer 1

Highly metabolically active small cuboidal cells - basal cell layer - usually one cell thick Odland bodies - granular layer - 2or3 layers thick Corneocytes - keratin layer (terminal differentiation of keratinocytes) Polyhedral cells with lots of desmosomes - pricke cell layer

Question 2

Which of the following statements are true (must select all correct answers - ie more than 1) Select one or more:

• Approximately 19% of the population have a skin disease at any given time
• There are <500 skin known skin diseases
• The skin is the largest vital organ in the body
• Skin can provide an indicator of systemic disease

Answer 2

• The skin is the largest vital organ in the body - TRUE
• Skin can provide an indicator of systemic disease - TRUE
• Approximately 19% of the population have a skin disease at any given time - FALSE -
  
  • (Around 19% of GP consultations are for skin problems, but a higher number have a skin problem which may not require treatment or is being self-treated.)
• There are <500 skin known skin diseases - FALSE
  
  • There are over 2000 known skin diseases

Question 3

Panton valentine leukocidin is a cytotoxin associated with highly virulent strains of Staph. aureus causing necrolytic skin infections by directly killing leukocytes. State the mechanism of action of the other examples of virulence factor: * Impedin * Invasin * Adhesin * Aggressin * Modulin

Answer 3

* Impedin enables the organism to avoid host defences * Invasin enables the organism to invade a host tissue * Adhesion enables the organism to bind to the host tissue * Aggressin causes direct damage to the host * Modulin causes indirect damage to the host

Question 4

Which ONE of the following statements is TRUE regarding mucosal membranes. Select one: They are rarely affected by skin diseases They are usually keratinised They are highly specialised for function They do not have any sensory function They do not contain glands

Answer 4

They are highly specialised for functions - TRUE Mucosal membranes are often affected by skin disease e.g. blistering diseases. They aren’t keratinised, have many sensory functions e.g. taste, and often contain glands e.g. lacrimal glands, sebaceous glands

Question 5

Which of the following are functions of the skin? (Must select ALL correct answers to gain marks) Select one or more: Barrier function Thermo regulation Immune defense Metabolism and detoxification Communication Sensory

Answer 5

ALL TRUE - skin functions Barrier function Thermo regulation Immune defense Metabolism and detoxification Communication Sensory

Question 6

https://s3.amazonaws.com/classconnection/403/flashcards/11907403/png/ppngjpgpngjpg-17205C4796852250D50.png

Answer 6

A well defined scaly plaque

Question 7

Select the correct definition for the term PREVALENCE. Select one: The number of new cases of a disease in a population over a given period of time The proportion of a population affected by a disease at any given time The proportion of a population that have ever suffered from a specific disease The proportion of a population that have been affected by a disease in the preceding 1 year

Answer 7

Prevalence is The proportion of a population affected by a disease at any given time

Question 8

softening and breaking down of skin resulting from prolonged exposure to moisture What is this?

Answer 8

Maceration

Question 9

https://s3.amazonaws.com/classconnection/403/flashcards/11907403/png/ppngjpgpngjpgpngjpg-17205C660FE3BAA2258.png

Answer 9

* 1 - Crust * 2 - Fissure * 3 - Erosion * 4 - Maceration * 5 - Ulcer * 6 - Lichenification - area of hardened thickened skin usually fro rubbing or itching * 7 - Scale * 8 - Atrophy

Question 10

https://s3.amazonaws.com/classconnection/403/flashcards/11907403/jpg/ppngjpgpngjpgpng-17205C84B156D5AFE2E.jpg

Answer 10

Erythropoietic protoporphyria - deficiency in ferrochelatase resulting in build up of protoporphyrin IX Child crying when in direct sunlight –> burning, itching, scarring

Question 11

Which of the following is a component of the strain of MRSA (Methicillin Resistant Staphylococcus Aureus) which causes severe skin infection such as necrotising fasciitis? Select one: * Hyaluronidase * Coagulase * Protein A * Panton Valentine Leukocidin * Fibrinolysin

Answer 11

Panton Valentine Leukocidin

Question 12

What is the mediator of each type of hypersensitivity?

Answer 12

Type 1 - IgE Type 2 - direct cell killing (IgG and IgM) Type III - immune complex deposition - IgG and IgM Type IV - Th1 cell mediated

Question 13

Regarding topical steroids, which ONE of the following is TRUE? Select one:

• They have a vaso-dilatory effect
• They cross the plasma membrane by endocytosis
• They increase cell proliferation
• They are lipophilic
• Absorption is greater across hyperkeratotic than atrophic skin

Answer 13

The correct answer is ‘they are lipophilic’ - this allows passive diffusion across the plasma membrane where they combine with cell receptors and bind to steroid responsive elements in the DNA.

• They are anti-proliferatives, anti-inflammatory and vasoconstrictive.
• Absorption is affected by skin thickness, skin state, occlusion, the vehicle used and drug concentration.

Question 14

For each of the following skin functions, select the cell or structure responsible Vitamin D metabolism Energy storage Tensile Strength Epidermal proliferation Release of inflammatory mediators

Answer 14

Vitamin D metabolism - keratinocytes Energy storage - subcutaneous fat Tensile Strength - collagen Epidermal proliferation - basal cell layer Release of inflammatory mediators - mast cells

Question 15

https://s3.amazonaws.com/classconnection/403/flashcards/11907403/png/ppngjpgpngjpgpngjpgpngjpgpngjpg-17205CD52466CF8A02D.png

Answer 15

A - keratin layer B - granular layer C - prickle cell layer D - basal cell layer E - dermo-epidermal junction (epidermal basement membrane) F - dermis

Question 16

What has been defined as loss of normal temperature control with inability to maintain the core body temperature, and failure to prevent percutaneous loss of fluid, electrolytes and protein, with resulting imbalance, and failure of the mechanical barrier to prevent penetration of foreign materials?

Answer 16

SKIN FAILURE * Loss of temp control * Loss of fluid * Loss of electrolytes * Loss of proteins * Failure to prevent penetration of foreign materials

Question 17

Describe the function of the following in the skin Meissner’s corpuscles Eccrine glands Sebaceous glands Apocrine glands Pacinian Corpuscles Lymphatics

Answer 17

Meissner’s corpuscles - vibration sensation Eccrine glands - found in virtually all skin with highest densitiy in the palms and soles of feet to moisten for grip Sebaceous glands - maintain skin barrier by producing sebum (oily fluid) Apocrine glands - produce a fluid which becomes odourous on bacterial decomposition (scent gland) Pacinian Corpuscles - pressure sensation Lymphatics - immune surveillance

Question 18

The developmental growth pattern of skin follows which lines?

Answer 18

Blaschko’s lines

Question 19

Which of the following is true regarding nails Select one: Nails are formed from modified bony tissue Nails grow 1mm in a day Toe nails grow faster than fingernails Nails are rarely affected by disease Nails are biochemically similar to hair

Answer 19

Nails are biochemically similar to hair - TRUE Nails are formed from hard, densely packed keratin, like hair Nails grow 0.1 mm per day with fingernails growing faster than toe nails (and faster in summer than in winter) Nails are commonly affected by disease eg oncholysis (separation of nail from nail bed) in psoriasis

Question 20

Regarding normal skin, which ONE of the following is true? Select one: It takes 28 days for a cell to migrate from the basal layer to the keratin layer Cells become enucleated in the prickle cell layer The keratin layer is 100% keratin and filaggrin The granular layer is usually about 10 cells thick The term ‘prickle cell’ is used because of the presence of abundant intracellular filaments

Answer 20

It takes 28 days for a cell to migrate from the basal layer to the keratin layer - TRUE * Cells become enucleated in the granular layer * Keratin layer is 80% keratin and filaggrin * Granular layer is usually 2or3 cells thick * The filaments are intracellular

Question 21

During foetal development, which ONE of the following is true? Select one: Development of the skin is complete by 5 months gestation Langerhans cells migrate to the skin from the neural crest Blaschko’s lines develop in the distribution of cutaneous nerves The granular layer of the epidermis is the most metabolically active The basal layer of the epidermis is the most metabolically active

Answer 21

The basal layer is the most metabolically active - TRUE Sweat glands do not develop until 6 months gestation. Melanocytes migrate to the skin from the neural crest. The Blaschko pattern is developmental and not along nerves, vessels or lymphatics. The basal layer is the most metabolically active.

Question 22

A 3 year old boy presents on a sunny day in June. His mother reports he keeps crying and rubs at his skin when playing outside and this has been going on for a few weeks. His skin is sometimes a bit red, but there is never a rash and his skin is clear on examination now. He is skin type 1 with a few freckles evident, generally well, on no medication and there is no family history of skin problems. * What is the most likely diagnosis? * What investigation? * What treatment?

Answer 22

Erythropoietic protoporphyria Diagnose by measuring circulating flourescent red blood cells under UV light (fluorocytes) Treatment usually involves photoprotective measures Measure LFTs and RBC porphyrin every 6 months

Question 23

Which ONE of the following statements regarding Langerhans cells is FALSE. Select one: * They can be found in the prickle cell layer of the epidermis * They can be found in the dermis * They can be found in lymph nodes * They are formed in the liver * They present antigen to sensitised lymphocytes

Answer 23

Langerhans cells are formed in the liver - FALSE –> Langerhans cells are mesenchymal in origin and are formed in the bone Langerhans cells migrate throughout the epidermis and dermis, and travel via lymphatics to present antigen in lymph nodes. They are formed in bone marrow.

Question 24

What is the enzyme deficiency in acute intermittent protoporphyria? What are the presenting features?

Answer 24

Acute intermittent porphyria is due to impaired function of Porphobilinogen deaminase which results in an acute neurotoxic reaction in many tissues.- build up of porphobilinogen * NEVER ANY CUTANEOUS FEATURES * GI features- abdo pain, vomiting, constipation * Neurological features - psychosis, peripheral neuropathy * Tachycardias * Intermittent dark urine

Question 25

https://s3.amazonaws.com/classconnection/403/flashcards/11907403/png/ppngjpgpngjpgpngjpg-17205E0A93A5605ACFA.png

Answer 25

Tensile strength - collagen which is found in the dermis - G Energy storage - subcutaneous fat - so E Epidermal proliferaton is in the basal cell layer - so C Vitamin D metabolism is in keratinocytes - labelled B (unsure how im meant to see this tbh)

Question 26

Which of the following are present in the dermis? (You must select ALL correct answers to gain marks) Select one or more: * Fibroblasts * Lymphatics * Keratinocytes * Hemi-desmosomes * Ground substance

Answer 26

Found in dermis Fibroblasts Lymphatics Ground substance Collagen Keratinocytes are confined to the epidermis and hemi-desmosomes are found within the dermo-epidermal junction.

Question 27

https://s3.amazonaws.com/classconnection/403/flashcards/11907403/png/ppngjpgpngjpgpngjpg-17205E2D8820945BDFB.png

Answer 27

1 - bulla 2 - papule 3 - plaque 4 - pustule 5 - nodule 6 - wheal 7 - vesicle 8 - macule

Question 28

Skin problems make up what percentage of all general practice consultations Select one: * 0-8% * 9-14% * 15-23% * 24-29% * 30-36%

Answer 28

15-23% Correct is around 19% of all GP consultations

Question 29

Hyponychium Lunula Nail matrix Nail bed Nail plate

Answer 29

Hyponchium - G the area of epithelium, particularly the thickened portion, underlying the free edge of the nail plate on the nail Lunula - B Nail matrix - E Nail bed - F Nail plate - A

Question 30

https://s3.amazonaws.com/classconnection/403/flashcards/11907403/png/ppngjpgpngjpgpngjpg-17205E65BA6532BE77B.png

Answer 30

Sebcaeous gland is labelled by both D and H Fibroblast - found in the dermis - so G Keratin layer - A Melanocytes - labelled C (unsure how we can see this)

Question 31

Which cell or structure of the skin corresponds to the following function? * DNA Protection from Ultraviolet Radiation, * Temperature Regulation, * Collagen Synthesis, * Waterproof Barrier, * Skin Lubrication

Answer 31

DNA Protection from Ultraviolet Radiation- melanocytes Temperature Regulation,- blood vessels Collagen Synthesis,- fibroblasts Waterproof Barrier,- keratin layer (high lipid content due to lamellar organelles from the granular layer releaseing lipid content) Skin Lubrication - sebaceous gland

Question 32

A 13 year old girl develops lip and tongue swelling 5 minutes after eating a prawn sandwich. This reaction is: Select one: Type IV hypersensitivity reaction mediated by T lymphocytes Type I hypersensitivity reaction mediated by IgE Type II hypersensitivity reaction mediated by complement Type II hypersensitivity reaction mediated by histamine Type IV hypersensitivity reaction mediated by B lymphocytes Type I hypersensitivity reaction mediated by mast cells

Answer 32

Type I hypersensitivity reaction mediated by IgE This is a rapid response to an allergen so it is a hypersensitivity type I reaction, which are mediated by IgE

Question 33

Which of the following statements are TRUE? (Must select ALL correct answers to gain marks) Select one or more:

• * Apocrine glands are affected in acne
• * Sebaceous glands are attached to hair follicles in the skin
• * Acne is common pre-puberty
• * Eccrine glands are the commonest sweat glands on the face
• * A main function of apocrine glands is cooling of the skin

Answer 33

Correct answers are ‘sebaceous glands are attached to hair follicles in the skin’ and ‘eccrine glands are the commonest sweat glands on the face’.

• Sebaceous glands are affected in acne and a surge in androgens at puberty stimulates their production of sebum.
• Eccrine sweat glands play a role in temperature regulation.
• Apocrine glands are involved in scent. (also androgen dependent)

Question 34

A 58 year old man presents in July with blisters on the dorsal aspect of his hands which have been appearing over the last few months, crust over and heal leaving scarring. He works as a joiner and is aware that his skin has also been more fragile than usual. You notice that he has a lot of hair growing on his cheeks. He is generally well and on no medication * What is the most likely diagnosis? * What is the presentation?

Answer 34

Porphyria cutanea tarda Presentation in adult with blisters and fragility Hypertrichosis- excess hair growth (usually on cheeks) Hyperpigmentation is also a symptom