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Derm > Ch0 Basic Principles > Flashcards

Ch0 Basic Principles Flashcards

1
Q

What is erythema caused by

A

Erythema is caused by vasodilation and/or increased blood flow within the dermis

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2
Q

Entities that have the Koebner phenomenon

A
  • psoriasis
  • vitiligo
  • lichen planus
  • lichen nitidus
  • cutaneous small vessel vasculitis
  • Still disease
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3
Q

What does Woods lamp emit

A

UVA at 365 nm

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4
Q

How does a Woods lamp work

A
  • lamp 4-5 inches away from where you are examining
  • after the target absorbs the UVA radiation, there is some loss of energy and therefore the emission is at a longer wavelength within the visible range
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5
Q

What does vitiligo look like under woods lamp

A

chalk-white to dullish blue - fluorescence of dermal collagen observed due to a marked decrease or absence of melanin within the epidermis

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6
Q

Hyperpigmentation under Woods lamp

A
  • Epidermal melanin –> enhances brown colour

- Dermal melanin –> difference between lesional and non-lesional skin becomes less obvious

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7
Q

Pseudomonas under Woods lamp

A

Green

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8
Q

Corynebacterium under Woods lamp

A

Coral red

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9
Q

P acnes under woods lamp

A

Orange-red (in comedones)

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10
Q

Pit versicolor under Woods lamp

A

Yellowish-white
Yellow-green
Golden
Copper-orange

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11
Q

Tinea capitis under Woods lamp due to Microsporun

A

Blue-green to yellow-green

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12
Q

Trichophyton schoenleinlii under Woods lamp

A

blue-wehite

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13
Q

How long does parakeratosis take to develop (scale)

A

2 weeks

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14
Q

How long does tense bullae last for

A

less than a week

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15
Q

Causes of a rash and fever

A
  • Infectious
    • Bacteria: toxic shock, SSSS, scarlet fever, septic emboli, secondary syphilis
    • Viruses: exanthems, disseminated zoster
    • Fungi
    • Protozoa
  • Kawasaki
  • Inflam:
    • Drug reactions - DRESS< AGEP
    • EM, SJS
    • Primary cutaneous disorders
    • Rheum disorders
    • GVHD
  • Neoplastic: lymphoma
  • Inherited
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16
Q

Acute cutaneous eruptions in otherwise healthy individuals

A
  • urticaria
  • acute allergic contact dermatitis, ICD
  • Drug eruptions
  • Pit rosea
  • Viral exanthems
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17
Q

Where to biopsy in vasculitides

A

Centre of early lesion

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18
Q

Where to biopsy in livedo reticularis

A

centre of pale areas defined by surrounding venous plexus network, corresponds to site of ascending arteriole

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19
Q

Where to biopsy CT disease

A

fully developed lesion, not scarred

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20
Q

Where to biopsy alopecia

A

Active advancing edge, ares of perifollicular inflammation

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21
Q

Where to biopsy infectious

A

Mature lesions, if ulcerated inflammatory border

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22
Q

Ulcerative dermatoses where to biopsy

A

Active edge of ulcer or early lesion

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23
Q

Where to biopsy pigmentary lesion

A

Get non-lesional skin as well

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24
Q

Where to biopsy urticaria

A

Edge of lesion as well

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25
Q

Vacuolar definition

A

Degeneration of basilar keratinocytes with little or no inflammation

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26
Q

Lichenoid definition

A

lymphocytes directly engaged in the destruction of basilar keratinocytes

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27
Q

Spongiosis definition

A
  • intercellular oedema, widened spaces between keratinocytes with elongation of intercellular bridges. Often associated with exocytosis of inflammatory cells
    • Acute, subacute, chronic
    • When chronic - may be more acanthosis (thickening of the epidermis)
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28
Q

Psoriasiform definition

A

Epidermal hyperplasia - elongation of rete ridges

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29
Q

Pseudoepitheliomatous hyperplasia definition

A

related to psoriasiform - irregular, hyperplasia of the epidermis and/or adnexal structures. Can occur from chronic rubbing/scratching, but can be with inflammatory etc

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30
Q

Acantholysis definition

A
  • discohesion of keratinocytes due to disruption of desmosomes
  • Identifying level of epidermis
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31
Q

Ballooning degeneration definition

A

intracellular oedema in response to cytotoxic events –> presence of abundant pale cytoplasm of keratinocytes in the spinous zone. When ballooning is severe –> keratinocyte rupture –> reticular degeneration and epidermal necrosis

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32
Q

Granulomatous vasculitis

A

histiocytes within and around BV walls with fibrin/degenerative and necrotic changes. Seen in a restricted group of diseases: GPA, EGPA, temporal arteritis

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33
Q

Nodular and diffuse dermatitis definition

A

similar to perivascular dermatitis, but inflammatory infiltrate has enlarged and coalesced to form one or multiple nodules within the dermis

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34
Q

4 histopathologic types of granulomas

A
  • Tuberculoid –> epithelioid histiocytes, surrounded by a dense infiltrate of lymphocytes and plasma cells, +/- central caseation. May be Langhan type, associated with cutaneous infections, lupus miliaris
  • Sarcoidal –> epithelioid histiocytes with minimal lymphocytic infiltrate - naked tubercles
  • Palisaded ‘necrobiotic’ - epithelioid histiocytes aligned as a rim around a central area of degenerated collagen with different tinctorial qualities. All palisaded granulomas are markedly palisaded, and histiocytes may be distributed interstitially –> interstitial granuloma
  • Suppurative –> comprised of neutrophils within and sometimes among or surrounding, aggregates of epithelioid histiocytes
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35
Q

Langerhan cell histiocytosis brief histo overview

A

reniform (kidney bean-shaped) nuceli, positive for S100, CD207 and CD1a

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36
Q

Non-LCH brief histo overview

A

range of cytologic features - vacuolated, spindle shaped, foamy, scalloped, oncocytic. S100-, CD1a- and CD68+ (nonspecific marker of histiocyte lineage)

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37
Q

Lipophage definition

A

Foamy histiocytes filled with lipid

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38
Q

Questions to ask when assessing panniculitis

A
  • septal or lobular?
  • vasculitis or no?
  • type of inflammatory infiltrate?
  • cytologic atypia?
  • fat necrosis - hyaline changes, basophilic saponification
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39
Q

Causes of invisible dermatoses

A

Stratum corneum:
Superficial infections - tinea versicolor, dermatophytosis, erythrasma, pitted keratolysis
Keratinization: ichthyosis, DSAP
Basilar layer - pigment issues: vitiligo, melasma, CALM
Superficial dermis:
Infestations - onchocerciasis,
Mast cells: TMEP
Endogenous deposition: macular amyloidosis
Superficial and deep:
Exogenous substance: argyria
Endogenous: systemic amyloidosis
Collagen: collagenoma, atrophoderma
Elastic tissue: naevus elasticus, anetoderma
Absence of normal epithelial structure:
hypohidrotic ectodermal dysplasia

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40
Q

What to do when deposition of materials within skin

A
  • some materials are limited to the cutaneous adnexa –> silver
  • polarized light or darkfield microscopy might be helpful
41
Q

H&E marks what

A
  • basophilic structures (nuclei and granular layer of the epidermis), eosin marks eosinophilic structures - cytoplasm, collagen, muscle, nerve, fibrin
    • Elastic tissue does not stain with H&E –> van Gieson
42
Q

Alcian blue

A

mucinoses, lupus, blue

43
Q

Leder

A

myeloid and mast cells

44
Q

Colloidal iron

A

mucinoses, lupus

45
Q

Congo red

46
Q

Crystal violet

A

Acid mucopolysaccharides and amyloid

47
Q

Fontana masson

A

Melanin, black

48
Q

Giemsa

A

Nuclei of cells, microorganisms - Leish, histo, mast cell granules

49
Q

Methenamine silver

A

Fungal cell walls, stains black

50
Q

Gram

A

Positive- blue

Negative - red

51
Q

Masson’s trichome

A

Smooth muscle - pink

Collagen - blue/green

52
Q

Myeloperoxidase

A

Immature myeloid cells - orange

53
Q

Orcein

A
  • for elastic tissue disorders
    • Collagen - pink
    • Elastic tissue - dark brown
    • Muscle and nerves - yellow
54
Q

PAS stain

A

glycogen, fungal walls, neutral mucopolysaccharides, fibrin, basement membranes, red –> mycotic infections, DLE, PCY

55
Q

Perls iron

A

haemosideron and ferric ions - blue

56
Q

Sudan black

A

lipids, black

57
Q

Sudan orange

A

Lipids, orange

58
Q

Van Gieson

A
  • Collagen - pink-red
  • Elastic - black
  • Muscles and nerves - yellow
59
Q

Von kossa

A

Calcium, black

60
Q

Ziehl-neelson

A

Acid fast bacteria, red

61
Q

What is immunohistochemistry

A

use of immunologic tehcniques to identify cellular antigens that are not visible
- antibody is conjugated to an enzyme that can catalyze a colour producing reaction when the antibody-enzyme conjugate is bound to the appropraite antigen within tissue - enzyme is often peroxidase

62
Q

Diagnosis of tumours with sebaceous differentiation

A

Adipophilin

63
Q

Distinguishes BCC from trichoepithelioma

64
Q

Distrinction of BCC from other cutaneous basaloid tumours

65
Q

Tubular differentiation in epithelial tumours, diagnosis of benign and malignant adnexal neoplasms

66
Q

Low molecular weight cytokeratin, in simple epithelia and Merkel cells
Specific for Merkel cell carcinoma
Cutaneous mets from different types of adenocarcinomas

67
Q

Ductal differentiation in eccrine and apocrine tumours

Positive in most sebaceous glands

68
Q

Breast carcinoma metastases

Sweat gland carcinoma with apocrine differentiation

A

Gross cystic disease fluid protein 15

69
Q

Myoepithelial neoplasms

Distinction of primary cutaneous adenocarcinoma (positive) versus cutaneous mets from visceral adenocarcinomas

70
Q

Screening tumours for epithelial origin

Useful for SCCs

A

Pancytokeratin AE1/AE3

71
Q

S100

A

Family of low molecular weight calcium binding proteins
Neural crest-derived cells
Use for: melanocytic naevi and melanoma, most sensitive marker for spindle cell/desmoplastic melanoma
Alsot stains malignant peripheral nerve sheath tumours and clear cell sarcoma

72
Q

Melan-A

A

Melanocytic naevi and melanomas

73
Q

HMB45

A

Melanocytic naevi and melanomas
Diminished straining with dermal descent more frequent in benign tumours
Also may stain melanosome-containing keratinocytes

74
Q

MITF

A

Nucleus of melanocytic naevus and melanoma cells
Positive staining in almost all melanoma subtypes (80-100%
Helps distinguish solar lentigo from lentigo maligna
Less specificity as can also stain non-melanocytic spindle cell tumours

75
Q

Tyrosinase

A

Enzyme involved in the initial steps of melanin and biosynthesis, expressed in melanocytes
High sensitivity and specificity
Sensitivity decreases with increased clinical stage
Not helpful in desmoplastic melanomas as only 6% positive

76
Q

SOX10

A

Highly sensitive for primary and metastatic melanomas
Expressed in all melanoma subtypes
Positive in clear cell sarcomas and peripheral nerve sheath tumours
Useful for detection of micromets in LN

77
Q

BRAF V600E

A

BRAF - serine/threonine protein kinase in the MAPK pathway
V600E - detected in ~ 50% of cutaneous melanomas
Detection of this leads to treatment with BRAF inhibitors
Also present in LCH

78
Q

P75

A

Helps to diagnose desmoplastic and neurotropic melanoma with S100 staining is weak or absent

79
Q

PNL2

A

Melanocytic anevi and melanomas
Not so positive in desmoplastic melanomas
Can be positive in clear cell sarcomas, PEComas and melanocytic schqannomas

80
Q

pHH3

A

Precise identification of mitoses within tumours

81
Q

Merkel cell carcinoma stains

A

Chromogranin
CK20
Neurofilament
Snyaptophysin

82
Q

CD31

A

Benign and malignant vascular neoplasms

Hsitiocytes also stain positively

83
Q

CD34

A

Benign and malignant vascular neoplasms
DFSP
Many cutaneous spindle cell neoplasms so poorly specific

84
Q

Bcl-2

A

Primary cutaneous diffuse large B-cell lymphoma
Distinguishes systemic/nodal follicular lymphomas with secondary skin involvement from primary cutaneous follicle centre lymphomas (negative)

85
Q

Bcl-6

A

Primary cutaneous follicle centre lymphoma
Reactive lymphoid follicles
T follicular helper cells

86
Q

Dermal and congenital naevi vessels

A

Comma vessels

87
Q

Melanoma and Spitz Naevi vessels

A

Dotted vessels

88
Q

Melanoma vessels

A

Linear irregular vessels

89
Q

What does hairpin vessels mean

A

keratinizing tumours, seb K and SCC

90
Q

Sebaceous hyperplasia vessels

A

Crown vessels

91
Q

sBCC vessels on dermoscopy

A

multiple blood crusts over a red background

92
Q

Red lacunas

A

Haemangioma

93
Q

Pyogenic granuloma dermoscopy vessels

A

Red homogenous areas intersected by whitish lines

94
Q

Features of seb k on dermoscopy

A
  • Light-brown fingerprint like structures
  • Cerebriform pattern
  • Comedo lie openings
  • Multiple milia-like cysts
95
Q

BCC dermoscopy features

A
  • Arborizing vessels
  • Leaf-like structures
  • Large blue-gray ovoid nests
  • Multiple blue-gray globules
  • Spoke wheel areas
  • Ulcerations
96
Q

Types of patterns of melanocytic lesions

A
  • Reticular
  • Globular
  • Cobblestone - intradermal melanocytic
  • Homogenous
  • Starburst - Spitz/Reed
  • Parallel - acral
97
Q

Acral naevi patterns

A
  • Parallel-furrow pattern
  • Lattice-like
  • Fibrillar
  • Parallel ridge pattern
98
Q

Menzies diagnostic criteria for melanoma

A
  • for a lesion to be diagnosed, must have neither or both negative features, and one or more of the nine positive features
  • Negative:
      1. Symmetry of pattern
      1. Presence of a single colour
  • Positive
      1. Blue-white veil
      1. Multiple brown dots
      1. pseudopods
    • Radial streaming
    • Scar-like depigmentation
    • Peripheral black dots/globules
    • Multiple - 5-6 colours
    • Multiple blue/grey dots
    • Broadened network

Derm (57 decks)

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