Dermatopathology

Question 1

The body surface is exposed to full range of potential external damaging factors such as?

Answer 1

physical trauma
heat
cold
UV irritation
toxic chemicals

Question 2

Most epithelial surfaces (eg. lining the respiratory, alimentary and urinary tracts) show only?

Answer 2

a limited range of disease processes
only half a dozen are inflammatory disorders
and only a handful of neoplastic disorder.

Question 3

How many different tumours could be exhibited on the skin?

Answer 3

30-40

Question 4

What is dermatitis?

Answer 4

The most commonly encountered skin diseases are inflammatory
termed dermatitis

These are usually due to:
allergic reactions
infection
contact toxins
or an unknown cause

Dermatitis is the name give to inflammatory lesions of the skin,
irrespective of whether they involve the dermis or epidermis.
In most cases they effect components of both.

Some patterns of inflammatory skin disease have characteristic patterns which allows them to be easily identified
Some are caused by micro- organisms such as bacteria or fungi
e.g. athletes foot, impetigo, ring worm
Some are caused by viruses:
e.g. herpes, varicella
But most are non- specific,
the most common being ECZEMA (which can have many causes)

Question 5

What is Non- Specific Dermatitis also known as?

Answer 5

Eczema

Question 6

What levels can Non- Specific Dermatitis – aka Eczema by divided into?

Answer 6

It can be acute, subacute or chronic.

Question 7

What is acute dermatitis?

Answer 7

skin becomes red (erythema), itchy & tender.
tiny blisters called vesicles form under the epidermis.
When the vesicles burst, they discharge clear yellow fluid & then crust over.
The reddening of the skin is due a chronic inflammatory cell infiltrate around blood vessels in the upper dermis.
Leakage of fluid from vessels may produce swelling in the upper dermis- which may cause the lesions to be slightly raised above the level of normal skin.

Question 8

What is chronic dermatitis?

Answer 8

Because the lesion is itchy in the acute stage, it is almost always scratched by the patient.
As a result, secondary changes occur as a result of repeated trauma, rather than the background disease.
Repeated trauma to lesions of acute eczema leads to chronic dermatitis.
Chronic, non- specific dermatitis is usually always the result of chronic trauma to the acute dermatitis lesions.
The skin is thickened, often cracked and covered by a thick opaque scale.
This scale is a greatly thickened layer of surface keratin termed Hyperkeratosis which overlays the epidermis.
This thickening termed acanthosis is a common feature of chronic inflammatory skin diseases– of many types!

Question 9

What is subacute dermatitis?

Answer 9

used to describe skin inflammation in which there are features of chronic dermatitis, alongside vesicle formation seen in acute dermatitis

Question 10

What is Atopic dermatitis?

Answer 10

Atopic Dermatitis is a common type of Non- Specific Dermatitis (Eczema)
Sometimes called Atopic Eczema
It usually begins in childhood and can persist into adulthood.
Has strong genetic links
Often (but not always!) associated with hypersensitivity reactions. e.g. hayfever, asthma etc

Question 11

What is Gravitation Dermatitis aka Varicose Eczema ?

Answer 11

affects ankle & lower leg of patients with varicose veins

Question 12

What is Irritant Contact Dermatitis?

Answer 12

Due to strong agents such as detergents which come into contact with the skin

Question 13

What is allergic contact dermatitis?

Answer 13

Due to being in contact with something they are allergic to:
Nickel (for example a watch strap), rubber or latex can be example.

Question 14

What is Seborrheic Dermatitis?

Answer 14

Reddened and inflamed skin which is covered by thick waxy or white scale.
Usually seen in skin creases, and often linked with a type of yeast.

Question 15

What is Psoriasis?

Answer 15

Is a chronic intermittent disease

Defined by:
red, raised plaques
covered by thick, silvery- white scales.
Silvery scales may lift off, revealing a small area of bleeding.

Commonly found:
Knees, elbows  typically EXTENSOR surfaces
Trunk & scalp
Can occur in skin creases (here silvery plaques may be absent)

The scales are composed of flakes of thickened surface keratin
The epidermis shows a characteristic pattern of abnormality
Long ridges separated by markedly edematous papillary dermis, in which there are large numbers of dilated capillaries.
It is these capillaries which bleed when the scale is lifted off.
With regards to the swollen epidermis, the overlying papillary dermis is often very thin.

Psoriasis can also affect the nail bed leading to pitting, thickening and eventual destruction of the nail

Question 16

What is pustular psoriasis?

Answer 16

A pattern which commonly affects the palms of the hands & the soles of the feet.

Here a large number of neutrophils collect which are visible to the naked eye as yellowish purulent blobs
known as pustules

Question 17

What is the clinical relevance of psoriasis?

Answer 17

1 in 3 people with psoriasis develop psoriatic arthritis

Question 18

infections of the skin may be due to?

Answer 18

Bacteria
Fungi
Virus- Most common

Question 19

What is the herpes virus?

Answer 19

E.g. Herpes Simplex type 1 (cold sores)
Herpes Simplex type 2 (genital herpes)
Herpes Zoster – Varicella (Chickenpox / Shingles)
All produce blistering lesions of the epidermis

Question 20

What is pox virus?

Answer 20

Multiple pale domed lesions on the trunk and face of children, adolescents and young adults.
Due to localised nodular thickening of the epidermis.

Question 21

What are infections caused by fungi?

Answer 21

In most cases, the fungi or yeast forms in the reside in the keratin layer of the skin surface.
Associated with a minimal inflammatory response in the epidermis and upper dermis
Commonly Conditions you will see
Nature of the lesion depends on the particular area of skin affected.
e.g Athletes Foot
Ring Worm
Tinea Capitis

Question 22

What is the bacterial infection, impetigo?

Answer 22

Caused by staphylococci & streptococci
Highly contagious!
Spreads rapidly through populations
Large epidermal blisters (bullae) develop
These are filled with either clear fluid
or neutrophil polymorphs to form a puss – containing blister (pustule)

Question 23

What is the bacterial infection, cellulitis?

Answer 23

Inflammation of the dermis & subcutis
Bacteria can extend into the fascia and underlying muscles where they can rapidly infiltrate and secrete toxins
this leads to rapid and extensive spread and necrosis of involved tissues
Called Necrotising Fasciitis
This occurs predominantly in the limbs
Amputation is sometimes necessary to prevent septicaemia.

Question 24

What is vasculitis?

Answer 24

Most frequently involved vessels in vasculitis are the small capillaries, arterioles and venules in the upper dermis.
Vascular damage to the walls leads to extravasation of red cells into the upper dermis
this produces lesions called:
Petechiae (when minute)
Purpura (when larger)
Some lesions when raised and nodular - called Palpable purpura

the most common causes of a vasculitic lesions are drug reactions.
But can also occur in SLE and Septicaemia.

Question 25

Vasculitis secondary to drug reaction. Common drugs which can cause skin reactions include?

Answer 25

Aspirin
Penicillin (antibiotic)
Agents added to food

Question 26

Tumours can be subdivided into those derived from the:

Answer 26

Cells of the epidermis
From skin appendages
those from connective tissues in the dermis.

Most commonly originate from the
keratinocytes or
melanocytes

Question 27

What are Keratinocytes?

Answer 27

Form a barrier against the external environment and play an important role in wound repair

Question 28

What are Melanocytes?

Answer 28

Are the pigmented cells of the skin
Found in the basal later of the epidermis but have long arms which extend upwards.

Question 29

What are the 2 main types of Keratinocyte – Derived Tumours?

Answer 29

Basal Cell Carcinoma & Squamous Cell Carcinoma

Both are predisposed by exposure to light & ionising radiations
Therefore most likely to be seen in sun exposed areas such as the head & neck and hands.

Question 30

What is a basal cell carcinoma?

Answer 30

Can appear as a firm raised nodule (nodular basal cell)
flat, thickened or whitish (morpheic basal cell)
Superficial Basal Cell (flat red with irregular edge)

All basal cell carcinoma’s can be cured if completed removed. However reoccurance is a common problem.

Question 31

What is a squamous cell carcinoma?

Answer 31

Can appear as irregular plaques or patches
with rough hard hyperkeratotic surfaces.
Lesions can appear flat or raised
reddish – brown

Unlike basal cells, these have the potential for metastases.
usually spreading to local lymph nodes

Question 32

What are melanocyte derived tumours?

Answer 32

Melanocytes nevi – commonly known as “moles”
These are extremely common
Most individuals have a few, whilst others can have large amount of moles all over their bodies.

The vast majority of nevi are completely benign, but occasionally malignant change occurs.

The vast majority of nevi are completely benign, but occasionally malignant change occurs.

Clinically, such malignant nevi may present as:
larger than usual (more than 1cm)
irregular edge
Irregular surface pigmentation

Any changes in a pre-existing mole requires urgent further investigation

Question 33

How many stages are there of melanoma?

Answer 33

0-4

Question 34

What is Haemangioma?

Answer 34

Haemangioma’s are frequently seen vascular lesions in the dermis
Not cancerous.

Examples include:
Capillary Haemangiomas
common in babies
usually seen on the trunk, buttocks or face.
Not present at birth, but develop a few months later.
usually 2-3cm in diameter

Question 35

What is Haemangioma - port wine stain?

Answer 35

Present at birth as a flat, purplish red or pink are on the face and neck
Occasionally present on the limbs
Sometimes associated with intracerebral vascular malformations. (Sturge- Weber Syndrome)

Question 36

What are keloid scars?

Answer 36

Most common non- neoplastic fibrous lesions of the dermis

Appear as:
Raised, Firm, Collagenous lesions
Grow slowly
become firmer in time
common in the upper arm & shoulders.

Lesions follow a history of trauma e.g ear piercing or repeated rugby tackles.
Cosmetically, can be an unwanted complication post surgery.