Pathology

Question 1

Seborrhoeic keratosis

• What is it?
• Who is it common in and where on the body?
• How do the lesions appear?
• Pathological features?

Answer 1

• Benign proliferation of epidermal keratinocytes
• Very common in ageing/elderly skin
• Common on face, chest and back
• Stuck on appearance - greasy hyperkeratotic surface
• Epidermal acanthosis, hyperkeratosis, horn cysts

Question 2

Eruptive appearance of many seborrhoeic lesions lesions in a short time period may indicate internal malignancy.
What sign is this?

Answer 2

Leser-Trelat sign

Question 3

Very hyperplastic keratin layer and horn cysts.

This is the histology of which condition?

Answer 3

Seborrhoeic keratosis

Question 4

How should you investigate seborrhoeic keratosis?

Answer 4

Curette and send for histology

Question 5

Who is basal cell carcinoma common among?

Answer 5

• Sun exposed sites
• UK - middle aged and elderly
• Australia - younger age groups

Question 6

What are the three main subtypes of basal cell carcinoma?

Answer 6

1. Nodular
2. Superficial
3. Infiltrative (morphoeic)

Question 7

How does a basal cell carcinoma develop?
Does it metastasize?
Can it kill?

Answer 7

• Basal cells sprout from epidermis
• Groups of cells invade dermis
• Peripheral palisading
• Mitoses and apoptoses very numerous
• Slow growing, locally destructive

Almost never metastasises
May kill by invading eye -> brain

Question 8

What is the most severe type of basal cell carcinoma and why?

Answer 8

Infiltrative type

• Margins are poorly defined
• May spread along nerves
• Resection may be challenging

Question 9

How does nodular basal cell carcinoma appear on histology?

Answer 9

Very well defined; nodules of basal cells which spread down into the dermis

Question 10

What can superficial BCC mimic?

Answer 10

Eczema

Question 11

How does infiltrative BCC show on histology?

Answer 11

Desmoplastic stroma

Question 12

Give three common precursors of squamous cell carcinoma.

What do they have in common?

Answer 12

1. Bowen’s disease – occurs especially on legs
2. Actinic keratosis – little scaly things especially on head/neck
3. Viral lesions - especially on anogenital skin
   All show squamous dysplasia

Question 13

Bowen’s disease

• What is it?
• Who gets it and where on the body?
• How does it appear?
• is it invasive?
• What can it mimic?

Answer 13

• This is squamous cell carcinoma in –situ
• Female excess – mostly presents on lower leg
• A well-defined, slowly enlarging, red scaly plaque with irregular border
• No dermal invasion
• Can be erythematous and hence mimic inflammatory conditions in some cases

Question 14

Actinic keratosis

• Where on the body?
• Precursor of?
• What does histology show?

Answer 14

• Sun-exposed skin esp. scalp, face, hands
• Common precursor of invasive SCC
• Histology shows parakeratosis with moderate squamous dysplasia

Question 15

What is Erythroplasia of Queryat

Which pathogen is it associated with?

Answer 15

Penile Bowen’s disease

Associated with HPV

Question 16

What are the most common sites for SCC?

What are some less common sites?

Answer 16

Elderly, sun exposed sites (face, ears, dorsal hands)
Occasionally arises
- Chronic leg ulcers e.g. stasis ulcers
- Sites of burns; sinuses e.g. chronic osteomyelitis
- Chronic lupus vulgaris

Question 17

How does SCC tend to behave?

Answer 17

• Generally good prognosis
• Locally invasive
• Low but definite risk of metastasis

Question 18

What are some adverse prognostic features of SCC?

Answer 18

• Thickness > 4mm and poor differentiation
• Lymphatic / vascular space invasion
• Perineural spread
• Specific sites poorer prognosis - scalp, ear, nose

Question 19

Where does SCC tend to metastasize to?

Answer 19

Lymph nodes

Question 20

Which type of tumour can develop after an insect bite?

Answer 20

Dermatofibroma

Question 21

What is Merkel cell cancer?

Answer 21

Neuroendocrine cancer of cells which detect pressure

Question 22

Where are melanocytes derived from?

Answer 22

Neural crest

Question 23

Aside from the skin where else can you get melanomas?

Answer 23

Eye

Meninges

Question 24

Where in the skin do melanocytes reside?

Answer 24

Basal layer

Question 25

How does melanocyte ratio vary with race?

Answer 25

Ratio is constant irrespective of race

Question 26

Which gene governs production of melanin? Which type of melanin determines hair colour? Which type for red hair?

Answer 26

Eumelanin (other than red) | Phaeomelanin for red hair

Question 27

What is the tole of MC1R in red hair?

Answer 27

MC1R turns phaeomelanin into eumelanin One defective copy of MC1R causes freckling Two defective copies-red hair and freckles!

Question 28

What is the proper name for freckle? | What is a freckle?

Answer 28

Ephilide | Patchy increase in melanin pigmentation – where the distribution of melanocytes is increased in a particular area

Question 29

What is actinic lentigines?

Answer 29

Aka sun spot - related to UV exposure | Basically increased melanin and basal melanocytes

Question 30

What are most melanocytic naevi acquired?

Answer 30

1st and 2nd decades

Question 31

What is the risk with giant congenital melanocytic naevus?

Answer 31

Melanoma

Question 32

Describe the steps of melanocytis naevus development

Answer 32

1. Childhood - junctional naevus - melanocytes proliferate, clusters of cells at DEJ 2. Adolescense - compound naevus - junctional clusters + groups of cells in dermis 3. Adulthood - intradermal naevus - all junctional activity has ceased, entirely dermal

Question 33

What is a dysplastic naevi? | Clinical features?

Answer 33

These are an intermediate between melanocytic naevi and melanoma - Generally >6mm diameter - Variegated pigment - Border asymmetry

Question 34

What are the two typical clinical settings for dysplastic naevus? Give some features of each.

Answer 34

Sporadic - Not inherited - One to several atypical naevi - Risk of MM slightly raised Familial - Strong FH of melanoma - Autosomal inheritance - High penetrance - Atypical naevi+++ - Lifetime risk melanoma up to 100%

Question 35

Halo naevi - How does it appear? - Associated with which cell type? - Pathology?

Answer 35

- Have a peripheral halo of depigmentation. - Show inflammatory regression and are overrun by lymphocytes - Body decides to attack the naevus and the skin surrounding it loses its pigment

Question 36

Blue naevi - Which layer of skin? - Consist of which type of cell? - How do they appear?

Answer 36

- Entirely dermal - Consist of pigment rich dendritic spindle cell - Looks blue because of light scattering effect of the epidermis

Question 37

Spitz naevus - Age group? - Consist of which type of cell? - What do they mimic? - What do they often look like?

Answer 37

- Usually occur <20 years - Consist of large spindle and/or epithelioid cells - May closely mimic melanoma, although most are entirely benign - difficult area as there is a malignant variant! - Often look like haemangioma – note pink colouration opposite due to prominent vasculature

Question 38

What does a Spitz naevus closely resemble on histology?

Answer 38

Melanoma

Question 39

Melanoma - Which sites on the body? - Where else do they rarely occur?

Answer 39

Melanoma most common on sun-exposed sites scalp, face, neck, arm, trunk, leg. Rarely occur in eye, meninges, oesophagus, biliary tract, anus.

Question 40

What clinical features should make you suspect melanoma?

Answer 40

- Change in shape - Irregular pigmentation - Bleeding - Development of satellite nodules - Ulceration - New pigmented lesion develops in adulthood

Question 41

What are the four main types of MM?

Answer 41

1. Superficial spreading – most common in trunk and limbs 2. Acral/mucosal lentiginous - acral and mucosal 3. Lentigo maligna - sun-damaged face/neck/scalp 4. Nodular - varied sites but often trunk

Question 42

Which types of malignant melanoma grow similarly? | How do they tend to grow?

Answer 42

1. Superficial spreading melanoma 2. Acral/mucosal melanoma 3. Lentigo maligna Grow as macules when either entirely in-situ or with dermal microinvasion - this is RGP Eventually the melanoma cells invade the dermis forming an expansile mass with mitoses - this is VGP Only VGP melanomas can metastasise

Question 43

How is the growth of nodular melanoma different to that of the others?

Answer 43

Nodular melanoma – seems to bypass radial growth, instead just looks like a nodule from the outset

Question 44

How can you measure prognosis of melanoma?

Answer 44

Breslow depth = deepest tumour from granular layer

Question 45

Name and describe three ways in which melanomas can spread

Answer 45

1. Local dermal lymphatics -> satellite deposits of MM 2. Regional lymph node metastases – common pattern of disease progression Nodes excised (radical lymphadenectomy) 3. Blood spread - Skin / soft tissue - Heart, lungs - GI tract, liver - Brain

Question 46

Describe the treatment of melanoma

Answer 46

- Primary excision to give clear margins - Some also receive a sentinel node biopsy - If SN positive - regional lymphadenectomy - Treatment of advanced disease difficult - Chemo, immunotherapy, genetic therapies