Introduction to Dermatology

Question 1

What is the structure and function of the subcutaneous layer of skin?

Answer 1

Structure: Fat energy store

Function: Insultation

Structure: Fibrous bands

Function: Anchor skin to fascia

Question 2

What is the structure of the dermis?

Answer 2

Collagen and elastin matrix with mucopolysaccharide gel also fibroblasts, dermal dendritis cells and macrophages

Question 3

What are the three cell types found in the epidermis?

Answer 3

Epidermis: Keratinocytes (majority of cells), melanocytes and langerhans cells

Question 4

What is the function of melanocytes?

Answer 4

Makes melanosomes (collections of melanin)

Question 5

What is the function of langerhans cells?

Answer 5

Process antigens and migrate to lymph nodes to induce an immune response

Question 6

What are the layers of the skin?

Answer 6

Question 7

What are the stages of the hair cycle?

Answer 7

Anagen - growing phase

Catagen - growth stops for 2-3 weeks, hair follicle shrinks

Telogen - Resting phase for 1-4 months

Question 8

What are the functions of skin?

Answer 8

•Thermoregulation

–Insulation, Heat transfer

•Skin immune system

–Innate and Adaptive functions

•Barrier

–Protects against Mechanical, Chemical, microorganisms, Ultraviolet light

–Keeps in water and Electrolytes, Macromolecules

•Sensation

–Temperature, touch and pain

•Vitamin D synthesis

–UV light converts 7-dehydrocholesterol to cholecalciferol

•Interpersonal Communication

–Physical appearance, smell, self -identity

Question 9

What are the causes of skin disease?

Answer 9

•External

–Temperature, UV, chemical (allergen or irritant), infection, trauma

(photosensitivity, cold injury (frost bite, utricaria, chilblains)

•Internal

–Systemic disease, genetics, drugs, infection, Autoimmune (bullous pemphigoid)

Question 10

Describe photosensitivity

Answer 10

Commonly caused by medications (NSAIDS, bendroflumethiazide)

Exposed sites are affected - may be sensitive to visible light or UV light

Question 11

What is utricaria?

Answer 11

Usually seen as a wheel on the skin

Urticaria – mast cells degranulate (spontaneous is most common) – nettle sting type reaction – can happen as a result of pressure, cold weather or even water

Question 12

Is dermatitis artefacta caused by internal or external reasons?

Answer 12

External:

Dermatitis artefacta is a condition in which skin lesions are solely produced or inflicted by the patient’s own actions. This usually occurs as a result or manifestation of a psychological problem. It could be a form of emotional release in situations of distress or part of an attention seeking behaviour.

Question 13

What words are used to describe the size of the skin lesion?

Answer 13

Macule Small circumscribed area

Patch Larger circumscribed area

(small means less than 5 mm)

Question 14

What words are used to describe if the skin lesion is raised or not raised?

Answer 14

Papule - small raised area

Plaque - large raised area

Question 15

What words are used to describe if the skin lesion is fluid filled?

Answer 15

Vesicle - small fluid filled

Bulla - large fluid filled

Question 16

What words are used to describe if the skin lesion is pus filled?

Answer 16

Pustule - small pus filled

Abscess - large pus filled

Question 17

What words are used to describe the depth of the skin lesions?

Answer 17

Erosion - Loss of Epidermis

Ulcer - Loss of Epidermis and dermis

Question 18

What are the most common skin conditions?

Answer 18

Question 19

Some conditions have cutaneous signs:

Answer 19

Erythema Nodosum

Sarcoidosis

Vasculitis

Malignancy

Auto-immune conditions

Question 20

What skin condition can happen as a result of abnormal lipid metabolism?

Answer 20

Eruptive xanthoma - hyperlipidaemia

Question 21

What is acanthosis nigricans assoicated with?

Answer 21

Insulin resistance

Obesity

Malignancy

Question 22

What are the features of acanthosis nigricans?

Answer 22

Hyperkeratosis

Hyperpigmentation

Papules

Velvety appearance

Flexural distribution

Question 23

What are the skin features of thyroid skin disease?

Answer 23

Myxoedema - swelling of the skin and underlying tissues - gives skin a waxy appearance - typical of patients with an underactive thyroid gland

Pretibial myxoedema

Mucinosis (fibroblasats produce abnormally large amounts of acid mucopolysaccharides) - causing eye disease

Other eye diseases are also common in thyroid skin disease

Question 24

What are the investiagations in dermatology?

Answer 24

Charcoal swab - you can’t swab for cellulitis - the investigation for cellulitis is blood culture

MC and S

Suspected viral infection - viral swab for PCR ( you can swab vesicles, bulla (ruptured) or throat)

Fungal infection (skin scraping, nail clipping, hair sample, fungal cultures)

Punch biopsy