Pathology of the Skin Flashcards

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1
Q

Parakeratosis

A

Persistence of nuclei in the keratin layer, due to excessive differentiation of keratinocytes and high speed of turnover

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2
Q

Hyperkeratosis

A

Increased thickness of keratin layer

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3
Q

Acanthosis

A

Increased thickness of epithelium

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4
Q

Papillomatosis

A

Irregular epithelial thickening

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5
Q

Spongiosis

A

Oedema fluid between squamous appears to increase prominence of intercellular prickles

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6
Q

What are the 4 main classifications of inflammatory skin disease?

A
  1. Spongiotic (intraepidermal oedema)
  2. Psorisiform (elongation of rete ridges)
  3. Lichenoid (basal layer damage)
  4. Vesiculobullous (blistering)
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7
Q

Koebner Phenomenon

A

Refers to skin lesions appearing on lines of trauma

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8
Q

What are the histological characteristics of Psoriasis?

A

Elongation, clubbing and fusion of the rate ridges, parakeratosis and superficial blood vessels

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9
Q

What is the most common lichenoid disorder?

A

Lichen planus - Itchy flat topped violaceous papules

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10
Q

What are histological features of lichen planus?

A

Irregular sawtooth acanthosis, pigment incontinence (pigments have dropped into the dermis due to damage to basal layer)

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11
Q

Which antibodies are involved in pemphigus vulgaris and bullous pemphigoid?

A

IgG

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12
Q

Which antibodies are involved in dermatitis herpetiformis?

A

IgA

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13
Q

Pemphigus

A

Rare autoimmune bulls disease, of which there are 4 types - the most common being pemphigus vulgaris

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14
Q

What is common to all variants of pemphigus?

A

Acantholysis - lysis of intercellular adhesion sites (cells all separate)

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15
Q

In pemphigus vulgaris, what do the autoantibodies act against?

A

Desmoglein 3 (maintains desmosomal attachments)

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16
Q

In bullous pemphigoid, what do the autoantibodies act against?

A

Antigen of the hemidesmosomes anchoring basal cells to basement membrane.

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17
Q

What is a hallmark of immunofluorescence in BP?

A

Linear arrangement of IgG fluorescence along basement membrane

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18
Q

What is the hallmark of dermatitis herpetiformitis?

A

Papillary dermal micro abscesses, particularly on the buttocks - look like ‘scratch lesions’

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19
Q

In dermatitis herpetiformitis, what do the autoantibodies act against?

A

Gliadin component of gluten but cross react with connective tissue matrix proteins

20
Q

Sites of which glands is acne associated with?

A

Sebaceous glands - therefore face, upper back and anterior chest are affected

21
Q

What are the 4 main factors in the aetiology of acne?

A
  1. Increased sebum production and thickness in response to androgens
  2. Blockage of sebum foreign comedones
  3. Builds up and ruptures causing inflammation
  4. Bacterial infections
22
Q

Which gene determines the balance go pigment in skin and hair?

A

Melanocortin 1 receptor gene (MC1R)

23
Q

What does Eumelanin and Phaeomelanin cause in terms of hair colour?

A

Eumelanin causes all hair colours except red, phaeomelanin causes red hair

24
Q

What does MC1R do in terms of eumelanain and phaeomelanin, and what does defective copies do?

A

MC1R turns phaeomelanin into eumelanin. One defective copy causes freckles, 2 defective copies causes red hair and freckles

25
Q

What are ephilides?

A

Freckles - Patchy increase in melanin pigmentation over a few rete ridges in the skin (reflects clumpy distribution of melanocytes)

26
Q

What are actinic lentigines?

A

Age/Liver spots - due to localised proliferation of melanocytes in areas of chronic sun exposure. They don’t fade in winter, unlike freckles.

27
Q

What are the 2 types of naevi?

A

Acquired (most common) or congenital

28
Q

What is the basis of acquired naevi?

A

During infancy the melanocytes:keratinocyte ratio breaks down at a number of cutaneous sites, allowing smoke naevi to form

29
Q

What is the developmental pathway for acquired naevi?

A
  • In childhood, junctional naevus forms, where clusters of melanocytes develop at DEJ.
  • Then in adolescence, compound naevus forms, with clusters at the epidermal junction and dermis.
  • Finally in adulthood, the intradermal naevus forms where the cluster is fully dermal
30
Q

What are dysplastic naevi?

A

‘Funny-Looking moles’ - may appear malignant, as they are variegated pigment, >6mm diameter, asymmetrical

31
Q

What are the 2 main types of dysplastic naevi?

A

Sporadic (not inherited, common in freckly red-heads) and Familial (inherited condition with high risk of melanoma and have hundreds of dysplastic naevi)

32
Q

What is this?

A

Halo Naevi (peripheral halo of depigmentation )

33
Q

What is this guy?

A

Blue naevi (entirely dermal, and consist of pigment rich dendritic spindle cells)

34
Q

What are spitz naevi?

A

Naevi that usually occur <20y, consiting of spindle/epitheliod cells. May mimic melanoma.

35
Q

Do most melanomas start ‘denovo’ or from dysplastic naevi?

A

De novo

36
Q

What are the 4 main types of malignant melanoma?

A
  1. Superficial spreading (commonest)
  2. Acral/mucosal lentiginos
  3. Lentigo maligna
  4. Nodular
37
Q

Radio-growth phase (RGP)

A

SSM, A/MLM and LMM all grow as macule outwards when either entirely in-situ or with dermal micro invasion

38
Q

Vertical growth phase (VGP)

A

Eventually the melanoma cells invade the dermis forming an expansile mass with mitoses - only this phase can metastasise

39
Q

Which melanomas shows no radio-growth phase, only vertical growth phase?

A

Nodular

40
Q

Breslow’s Depth

A

Deepest tumour from granular layer mm

41
Q

What are the classifications of tumour types in terms of depth?

A
42
Q

What would a suffix of a ‘b’ mean in tumour type?

A

It would indicate ulceration

43
Q

What clearance should be given in excision of different types of lesions?

A
  • If in-situ then clear by circa 5mm
  • If invasive but 1mm thick tjem 2cm clearance
  • Sentinel node biopsy (SNB) if >1mm thick or thinner with mitoses
44
Q

What is the key difference between freckles and naevi/lentigines?

A

Freckles are increase in melanin, while naevi/lentigines are an increase in the number of melanocytes

45
Q

What are seborrheic keratoses?

A

Benign skin tumour that originates from keratinocytes. Appear as brown/black greasy lesions with a ‘stuck on’ appearance

46
Q

What is a dermatofibroma?

A

A dermatofibroma is a common benign fibrous nodule that most often arises on the skin of the lower legs.

47
Q
A