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Sarah - Dermatohistopathology > DermPath rounds > Flashcards

DermPath rounds Flashcards

1
Q

Hairs are most likely to be pigmented (in pigmented coats) in which hair follicles, primary, secondary or both?

A

You are more likely to see pigmented hair in primary hair follicles.

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2
Q

Which structure of the hair is more likely to be visible in the primary hair follicle compared to a secondary hair follicle?

A

The medulla

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3
Q

What marks the transition of the infundibulum to the isthmus?

A

A ring of tricholemmal keratin

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4
Q

Which cornifies first, Henle’s or Huxley’s layer?

A

Henle’s layer (outermost layer of IRS)

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5
Q

Which cells in the follicle wall are indicative of a regressing hair follicle?

A

Apoptotic keratinocytes

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6
Q

If a hair follicle shows apoptotic keratinocytes and trichilemmal keratin, what stage is it in?

A

Catagen

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7
Q

Which unusual features can be seen in normal bovine skin?

A

Dilated sweat glands

Parakeratotic inner root sheath

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8
Q

What is a flame follicle?

A

Excessive trichilemmal keratin (produced by the ORS) that protrudes between keratinocytes
+/- hair shaft

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9
Q

What % of hairs in skin biopsies are in catagen?

A

1-2%

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10
Q

What is abnormal about the keratohyaline granules in hairless cats?

A

They are irregularly sized

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11
Q

When describing a pustule histopathologically, what are the key features?

A
  1. Size, width and location (e.g. interfollicular)
  2. Is it multilayered (pustules with overlying crust)
  3. Location in the epidermis (e.g. intracorneal, subcorneal)
  4. Content of pustule (not crust! e.g. degenerate or non-degenerate neutrophils)
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12
Q

Which species has lots of large sweat glands and low numbers of single hair follicles with bulbs that reach deep into the subcutis?

A

Pigs

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13
Q

What does a tuberculoid granuloma look like?

A

A central zone of neutrophils and necrosis surrounded by histiocytes, epithelioid macrophages, and giant cells, in turn surrounded by lymphocytes and an outer layer of fibroblasts

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14
Q

What does a sarcoidal granuloma look like?

A

It consists of epithelioid macrophages

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15
Q

Tuberculoid granulomas can be seen in which diseases?

A

Tuberculosis, feline leprosy, atypical mycobacterial infection, and Corynebacterium pseudotuberculosis infections.

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16
Q

Sarcoidal granulomas can be seen in which diseases?

A

Sterile sarcoidal granulomas and foreign-body reactions.

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17
Q

What is a palisading granuloma?

A

They are characterised by the alignment of histiocytes, such as staves around a central focus of collagen degeneration (feline, canine, and equine eosinophilic granuloma; equine mastocytoma); parasite or fungus (habronemiasis, pythiosis, conidiobolomycosis, basidiobolomycosis, demodicosis); lipids (xanthoma); or other foreign material (e.g., calcium as in dystrophic calcinosis cutis and calcinosis circumscripta).

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18
Q

What does an epithelioid macrophage look like?

A

Elongated or oval vesicular nuclei and abundant finely granular, eosinophilic cytoplasm with ill-defined cell borders.

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19
Q

What do Langhans MNGCs look like?

A

The nuclei form a circle or semicircle at the periphery of the cell

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20
Q

What do foreign body MNGCs look like?

A

The nuclei are scattered throughout the cytoplasm

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21
Q

What do Touton MNGCs look like?

A

The nuclei form a wreath that surrounds a central, homogeneous, amphophilic core of cytoplasm that is, in turn, surrounded by abundant foamy cytoplasm

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22
Q

Which type of MNGCs:

a) is strongly indicative of xanthomas
b) suggests the need for an acid-fast stain

A

a) Touton

b) Langhans

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23
Q

Which group of diseases has diffuse, compact orthokeratotic hyperkeratosis on histopathology?

A

Cornification disorders e.g. ichthyosis

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24
Q

A ‘wind-blown’ appearance of epidermal keratinocytes is typical of which disease?

A

Bowenoid in situ carcinoma

It can also affect the hair follicles

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25
Q

How big are erythrocytes, mast cells and keratinocytes?

A

Erythrocytes ~5-6um diameter
Mast cell ~15um diameter
Keratinocyte ~15-20um diameter

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26
Q

In which species is a lamellar appearance of the stratum corneum a normal finding?

A

Horses and cattle

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27
Q

Which granules within keratinocytes cannot be seen on H&E stained slides?

A

Lamellar granules

Can see keratohyalin granules only with H&E

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28
Q

Bacteria can produce which enzyme leading to dryness of the skin and impaired barrier function?

A

Ceramidase

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29
Q

Which structure is missing from the stratum corneum in JRTs with TGM-1 deficiency?

A

Cornified envelope is missing

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30
Q

What are the extracellular proteins of the desmosome?

A

Desmoglein and desmocollin

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31
Q

What are the intracellular proteins of the desmosome?

A

Plakophilin, plakoglobin and desmoplakin which are linked to keratin filaments

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32
Q

Where is desmocollin 1 expressed?

A

Stratum cornuem
Stratum granulosum
Haired skin and foot pads only, not found in the buccal mucosa

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33
Q

Where is desmocollin 3 expressed?

A

All layers of the epidermis in haired skin and foot pad and more strongly in basal layer of buccal mucosa than the superficial layers

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34
Q

Epidermolysis bullosa simplex is associated with mutations in which genes in cats and cattle?

A

KRT14 cats

KRT5 cattle

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35
Q

Palmoplantar keratoderma in the Dogue de Bordeaux is associated with which gene mutation?

A

KRT16

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36
Q

What are the two layers of the dermis called?

A

Papillary dermis and reticular dermis.

Papillary dermis is not easily seen in dogs and cats; easier to see in people, pigs and large animals. It has finer collagen fibres than the reticular dermis.

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37
Q

Which species have dilated sweat glands as a normal histopathological finding?

A

Cows and pigs

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38
Q

Which species have simple hair follicles?

A 
Equine
Bovine
Porcine
Murine
Ovine
Human
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39
Q

Which species have compound hair follicles?

A 
Canine
Feline
Rabbits
Caprine
Ovine
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40
Q

What features define the transition of the infundibulum to the isthmus?

A

Sebaceous gland duct and rim of trichilemmal keratin

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41
Q

What feature marks the transition from isthmus to inferior portion of the hair follicle?

A

The isthmus starts where the last cell of the inner root sheath is fully cornified (can no longer see pink keratohyalin granules)

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42
Q

How does cornification differ in anagen and telogen hair follicles?

A

Anagen show inner root sheath cornification

Telogen show trichilemmal cornification of the outer root sheath

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43
Q

What is iSALT and where is it found?

A

Inducible skin associated lymphoid tissue

Found at the post-capillary venules

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44
Q

Which species has the most brightly eosinophilic eosinophils?

A

Horse

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45
Q

What should you describe in the first sentence of a histopath report for a tumour?

A 
Location
Densely or sparsely cellular
Well or poorly demarcated
Shape (nodular, verrucous etc)
Expansile or infiltrative
Encapsulated or unencapsulated
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46
Q

How do you describe cell patterns in tumours?

A

Carcinoma: nests, packets, lobules, cords
Adenocarcinoma: tubules, acini
Sarcoma: bundles fasicles, streams
Round cells: sheets

Densely packed or loosely arranged
Stroma: fine, coarse, fibro vascular, pre-existing

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47
Q

How do you describe neoplastic cells?

A

Shape: round, spindle, oval, cuboidal, colnat, polygonal, pleomorphic
Size: small or large
Cell borders: distinct or indistinct
Cytoplasm: amount, colour, character
Nucleus: shape, location, chromatin distribution
Nucleolus: number, colour

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48
Q

Porphyria has been reported in which species?

A

Cattle, pigs and cats

It is caused by defective uroporphyrinogen III cosynthetase, an enzyme of hemoglobin synthesis

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49
Q

Secondary photosensitisation is caused by what?

A

Secondary photosensitisation is caused by defective liver function with subsequent accumulation of photodynamic phylloerythrin a chlorophyll metabolite

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50
Q

Primary photosensitisation is caused by what?

A

Primary photosensitisation is caused directly by chromophores from plants, drugs, or abnormal metabolites

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51
Q

What are the subcategories of mural folliculitis?

A

Interface
Infiltrative (lymphyocytes, eosinophils, granulomatous, destructive, necrotizing, mucinotic)
Pustular
Bulbitis

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52
Q

Name the superficial pustular diseases of the epidermis

A 
Impetigo
Superficial spreading pyoderma
Mucocutaneous candidiasis
Superficial spreading dermatophytosis
PF
PE
Subcorneal pustular dermatosis 
Sterile superficial erythroderma of miniature Schnauzers
Superficial drug reaction
Idiopathic linear pustular acantholytic dermatosis 
Dermatophilosis (equine)
Bovine papular stomatitis
Greasy pig disease (Staphylococcus hyicus)
53
Q

Name the bullous and vesicular diseases of the epidermis and dermal-epidermal junction

A 
Bullous pemphigoid
MMP
PV
PNP
Hereditary epidermolysis bullosa 
Epidermolysis bullosa acquisita 
Canine Darier's disease
Linear IgA disease
Mixed AISBD
Vesicular stomatitis
Swine vesicular disease
FMD (apthovirus)
Vesicular erythema of swine
Swine parvovirus vesicular disease
54
Q

Name the interface diseases of the dermal-epidermal junction

A 
DLE
SLE
PE
ECLE
VCLE
MCLE
Erythema ab igne
EM
Feline exfoliative dermatitis (+/- thymoma)
SLO
Juvenile onset ischaemic dermatopathy
Post rabies panniculitis
Generalised idiopathic ischaemic dermatopathy
Bovine viral diarrhoea
55
Q

Name the necrotizing diseases of the epidermis

A 
EM
Feline exfoliative dermatitis (+/- thymoma)
PNOE
TEN
Toxic shock syndrome
SND
Generic dog food dermatosis
Split pad disease
Burns
Irritant contact dermatitis
56
Q

Name the spongiotic and vesicular diseases of the epidermis

A 
Allergic contact 
Feline eosinophilic plaque
Psoriasiform dermatitis of pads
Facial dermatitis of Persian / Himalayan cats
Sarcoptes, psoroptes, chorioptes
Contact dermatitis
Viral vesicular dermatitis 
FMD
Orf (parapoxvirus)
Photosensitisation
57
Q

Name the ulcerative and crusting diseases of the epidermis

A 
Pyotraumatic dermatitis
Miliary dermatitis 
Mosquito bite hypersensitivity
Herpesvirus ulcerative dermatitis
Feline cowpox 
Indolent ulcer
Feline idiopathic ulcerative dermatosis
Canine pyoderma gangrenosum
Molluscum (equine - poxvirus)
Candidiasis
Dermatophilosis (bovine, equine)
Linear keratosis (equine)
58
Q

Name the hyperplastic diseases of the epidermis

A 
Chronic hyperplastic dermatitis
Fibropruritic nodules
Acral lick
Malassezia dermatitis
Actinic dermatitis / solar keratosis
Acanthosis nigricans (dachshunds)
Psoriasiform-lichenoid dermatosis (Springers)
Lichenoid keratosis
Inflamed linear epidermal nevus
Giant cell dermatosis in FeLV
Linear keratosis (equine)
59
Q

Name the diseases with abnormal cornification

A 
Primary seborrhea
Vitamin A responsive dermatosis
Canine ear margin seborrhea
Nasodigital hyperkeratosis
Nasal parakeratosis of Labradors
Congenital follicular parakeratosis 
Ichthyosis
Familiar pawpad hyperkeratosis
Schnauzer comedo syndrome
Actinic comedones
Callus
Sebaceous adenitis
Zinc-responsive dermatosis
SND
Inflamed linear epidermal nevus 
Acrodermatitis of bull terriers
Ulcerative nasal dermatitis in Bengals
60
Q

Name the perivascular disease of the dermis

A 
Superficial spreading pyoderma
Atopic dermatitis
Food allergy
FAD
Urticaria (allergic)
Allergic contact dermatitis 
Sarcoptes / Notoedres
Cheyletiellosis 
Feline superficial demodicosis
Cutaneous microfilariasis 
Hookworm dermatitis
Cutaneous anatrichosomiasis
Vitiligo
Onchocerca (equine) 
Habronema (equine)
Stephanofiliaria (bovine)
61
Q

Name the Vascular diseases of the dermis

A

Septic vasculitis
Urticaria and angioedema
Telangiectasia, phlebectasia and cutaneous flushing
Cyroglobulinaemia and cryofibrinogenaemia
Neutrophilic immunologic vasculitis
Cell poor vasculitis
Familial cutaneous vasculopathy of GSDs
CRGV
Proliferative thrombovascular necrosis of the pinnae
Proliferative arteritis of the nasal planum
Solar vasculopathy

62
Q

Name the lichenoid (Band- like) diseases of the dermis

A 
Mucocutaneous pyoderma
DLE
PF
VKH / uveodermatological syndrome
Psoriasiform-lichenoid dermatosis
Lichenoid keratosis
63
Q

Name the infectious nodular and diffuse granulomatous and pyogranulomatous diseases of the dermis

A

Actinomyces and nocardiosis
Bacterial pseudomycetoma
Feline leprosy
Canine leproid granuloma
Opportunistic mycobacterial infection (rapidly growing / atypical / nontuberculous)
Opportunistic mycobacterial infection (M. avium)
Dermatophytic (pseudo)mycetoma
Cutaneous blastomycosis, histoplasmosis and coccidiomycosis
Cutaneous cryptococcosis
Sporotrichosis
Opportunistic fungal infection
Cutaneous pythiosis, lagendiosis, entomophoromycosis
Leishmaniosis

64
Q

Name the noninfectious nodular and diffuse granulomatous and pyogranulomatous diseases of the dermis

A

Sterile granuloma and pyogranuloma syndrome
Reactive histiocytosis
Juvenile sterile granulomatous dermatitis and lymphadenitis (juvenile cellulitis, puppy strangles)
Adult sterile granulomatous dermatitis
Cutaneous xanthoma
Canine sarcoidosis
Foreign body reaction (foreign body granuloma)
Palisading granuloma
Localised and generalised granulomatous dermatitis (Eq. sarcoidosis)

65
Q

Name the nodular and diffuse diseases of the dermis with prominent eosinophils, neutrophils, or plasma cells

A

Arthropod reaction
Feline mosquito bite hypersensitivity
Spider bites
Fire ant bite
Feline herpes virus ulcerative dermatitis
Feline eosinophilic plaque
Feline indolent ulcer
Feline eosinophilc granuloma (feline collagenolytic granuloma, feline linear granuloma)
Canine eosinophilic granuloma
Canine eosinophilic dermatitis
Feline hypereosinophilic syndrome
Plasma cell pododermatitis
Familial cutaneous vasculopathy of german shepherd dogs
Canine sterile neutrophilic dermatosis (Sweet’s syndrome)
Sterile pustular erythroderma of miniature schnauzers
Well’s syndrome
Cutaneous mastocytosis

66
Q

Name the degenerative, dysplastic and depositional diseases of dermal connective tissue

A 
Calcinosis cutis
Calcinosis circumscripta
Cutaneous mucinosis
Cutaneous amyloidosis
Ehlers-danlos syndrome
Feline acquired skin fragility syndrome
Topical steroid reaction
Perforating dermatitis
Morphea
Cicatricial alopecia
Solar elastosis (solar dermatitis)
Erythema Ab Igne
67
Q

Name the pustular and nodular diseases without adnexal destruction

A 
Superficial bacterial folliculitis
Feline dermatophytosis
Canine dermatophytosis
PF 
Sterile eosinophilic pustulosis
Stralensia cynotis
68
Q

Name the pustular and nodular diseases with adnexal destruction

A

Deep bacterial folliculitis and furunculosis
German shepherd dog pyoderma
Post-grooming furunculosis
Acral lick dermatitis
Actinic furunculosis
Interdigital furunculosis (pedal folliculitis and furunculosis, interdigital pyoderma)
Callus pyoderma (pressure point pyoderma)
Canine acne (muzzle folliculitis and furunculosis)
Feline acne
Kerion
Canine demodicosis
Feline follicular demodicosis (d. mange, demodectic acariasis)
Pelodera dermatitis
Eosinophilic furunculosis of the face
Sebaceous adenitis
Stralensia cynotis

69
Q

Name the mural diseases of the hair follicle

A

Alopecia areata
Mural folliculitis due to demodicosis and dermatophytosis
Pseudopelade
Eosinophilic mural folliculitis in dogs
Degenerative mucinotic mural folliculitis in cats
Granulomatous mural folliculitis in dogs
Follicular mucinosis (alopecia mucinosa)
ILPAD (Idiopathic linear pustular acantholytic dermatosis)
Mural mucinotic isthmic folliculitis of Lundehunds
Proliferative, lymphocytic, infundibular, mural folliculitis and dermatitis with follicular apoptosis and parakeratosis (PLIMF)
Malignant catarrhal fever (ovine)

70
Q

Name the atrophic diseases of the adnexa

A

Hypothyroidism
Canine hyperglucocorticidism (canine hyperadrenocorticism, canine cushing)
Feline hyperglucocorticoidism (feline hyperadrenocorticism, feline cushing)
Canine sertoli cell tumour-associated skin disease (male feminizing syndrome)
Canine female hyperestrogenism (ovarian imbalance typeI)
Alopecia X
Post-clipping alopecia
Feline paraneoplastic alopecia
Acquired pattern alopecia (canine pinnal alopecia, pattern baldness, dachshund pattern baldness)
Ischemic dermatopathy/canine dermatomyositis
Post-traumatic alopecia
Traction alopecia (mechanical alopecia)
Telogen effluvium
Doxorubicin-induced alopecia
Excessive physiological shedding
Feline psychogenic alopecia

71
Q

Name the dysplastic diseases of the adnexa

A

Color dilution alopecia and black hair follicular dysplasia
Canine follicular dysplasia
Cyclical flank alopecia (seasonal flank alopecia, recurrent FA)
Congenital hypotrichosis
Follicular lipidosis
Sebaceous gland hyperplasia
Sebaceous gland dysplasia

72
Q

Name the diseases of the panniculus

A 
Post-rabies vaccination panniculitis
Post-injection panniculitis
Sterile abscess of repositol injection
Traumatic panniculitis
Vasculitic panniculitis of thermal burns
Idiopathic sterile nodular panniculitis
Vasculitic septal panniculitis (subcutaneous leukocytoklastic vasculitis)
Feline pansteatitis
Metatarsal fistulation of the german shepherd dog (sterile pedal panniculitis of the GSD, Deep metatarsal/metacarpal toritis in GSD)
Pancreatic panniculitis
73
Q

What four things should you first describe when looking at tumour?

A
  1. Demarcation
  2. Cellularity
  3. Infiltrative or expansive
  4. Capsule or not
74
Q

Name the types of round cell tumour in the skin

A 
MCT
Histiocytoma
Lymphoma
Plasmacytoma
Transmissible venereal tumour
75
Q

Which features can help to differentiate a histiocytoma from a lymphoma (both can be epitheliotropic)?

A
  1. Histiocytomas have a ‘bell’ shaped dome
  2. Histiocytomas have rete ridges associated with epidermal hyperplasia
  3. Histiocytomas have parallel sheets of round cells that ‘fall’ from the epidermis
  4. Histiocytes have more cytoplasm and bean shaped nuclei
76
Q

Where do you see lymphocytes appear in a regressing histiocytoma?

A

At the edges/base of the tumour - they infiltrate as the mass regresses

77
Q

Other than tumours, what other space occupying masses can be seen in the skin?

A

Cysts, hyperplasia, hamartoma

78
Q

Are benign or malignant tumours are more likely to have a capsule?

A

Benign

79
Q

Cells with nest/packet/lobule formation in tumours are most likely of what origin?

A

Epithelial

80
Q

Which round cell tumour is often associated with dilated sweat glands?

A

MCTs

81
Q

What can be seen within the abnormal vessels formed with haemangiosarcomas?

A

Thrombi

82
Q

What do you call an epitheliotropic lymphoma that only affects the epidermis?

A

Pagetoid reticulosis

83
Q

What are the neutrophils surrounding in this crust?

A

Bacterial colonies

84
Q

What is the arrow pointing at?

A

Acid fast bacillus within an epitheliod macrophage

85
Q

Histopath of crusted lesions from a goat; what is the arrow pointing at?

A

Paired cocci arranged in parallel rows with branching filaments

Dermatophilus congolensis

86
Q

What are pallisading granulomas?

A

Palisading granulomas are generally circumscribed infiltrates of histiocytes perpendicularly oriented to collagen fibers or foci of necrosis - inflammatory lesions.

Localized trauma/damage to collagen bundles may be the primary inciting cause.

87
Q

Match the IHC markers with the cells:
CD3, CD79b, Mum1
T cells, B cells and plasma cells

A 
CD3 = T cells 
CD79b = B cells 
Mum1 = plasma cells
88
Q

How do dermal dendritic and Langerhans cells differ in their IHC staining? Both are IBA1-positive.

A

Interstitial dendritic cells are E-cadherin-negative with variable CD204 labelling.

Langerhans cells are expected to be E-cadherin positive and CD204-negative

89
Q

When taking biopsies from alopecia, where should you sample?

A

Center/worst part of the lesion AND partially affected areas

90
Q

With loss of hair follicles, eg dysplasia, what happens to the epidermis?

A

It becomes hyperplastic and the stratum corneum is more compact (more like glaborous skin)

91
Q

What do you see on histopathology with trichotylomania?

A

Abnormally oriented fragments of hair shafts within the follicles - pulling on hair shafts leads to breakage and broken hairs within the follicle snap back

92
Q

A pale outer root sheath (contains glycogen) and trichohyaline granules are seen in which stage of the hair cycle?

A

Anagen

93
Q

Which changes, other than follicular arrest, can be seen on histopathology of HAC?

A

Epidermal and dermal atrophy
Comedone formation
Sebaceous gland atrophy
Calcinosis cutis (then see epidermal hyperplasia!)

94
Q

What is kenogen?

A

Hairless telogen with no evidence of a new anagen follicle developing (consequence of prolonged telogen)

95
Q

Which changes, other than follicular arrest, can be seen on histopathology of hypothyroidism?

A

Mucin deposition
Dermal thickening
Vavuolar changes in erector pili muscles (not very reliable change)

96
Q

What histopathological changes do you see with ischaemic dermatopathy?

A
  • Fading follicles
  • Pronounced follicular fibrous sheath
  • Deposition of fine fibrillar (wispy) collagen
  • Vascular walls are hyalinised/mummified with a lack of endothelial cells +/- leukocytoclasia
97
Q

Ear margin seborrhoea can be seen with which endocrinopathy?

A

Hypothyroidism

98
Q

What do you see on histopathology with feline paraneoplastic alopecia?

A

Epidermal hyperplasia

Miniaturised hair follicles (makes SG looks big!)

99
Q

Biopsy from a horse with scaling and alopecia on the face; what is the diagnosis?

A

Onchocerca (purple larvae on H&E)

100
Q

Can you see a clonal T cell population in inflammatory lesions?

A

Yes, rarely (e.g. drug reactions, ehrlichiosis)

101
Q

What histopathological changes do you see with alopecia X?

A

Prominent trichilemmal cornification of primary hairs (flame follicle)

Nordic breeds normally have increased trichilemmal keratin in telogen!

102
Q

Which non-inflammatory alopecia has these characteristic follicles?

A

Canine recurrent flank alopecia (witches feet)

103
Q

What mechanisms of keratinocyte necrosis are involved in confluent necrosis in SJS/TEN?

A
  1. Lymphocytes: Soluble cytotoxic proteins such as FasL and granulysin
  2. Macrophages/dendritic cells: TNF-alpha
    - TNF related apoptosis induced ligand (TRAIL) interacting with Apo2
    - TNF weak inducer of apoptosis (TWEAK) interacting with Apo3
104
Q

With viral triggers of EM, should you see viral inclusions at the site of EM lesions?

A

No - if you see viral inclusions then the pathology is due to antiviral cytotoxicity rather than EM

105
Q

PNOE in cats affects the pinna, ear canal and more rarely, which other sites?

A

Periocular, perioral and generalised

106
Q

What do you see on histopathology of Erythema ab igne?

A
  • Basal cell vacuolation
  • Apoptosis throughout epidermis
  • Dysplastic keratinocytes with karyomegaly
  • Wavy elastin fibres (red spaghetti)
  • Fibrosis
107
Q

Why do you not see many hair follicles in catagen?

A

It is the shortest phase of the hair cycle

108
Q

How many substages of catagen are there?

A

8

109
Q

How many substages of anagen are there?

A

6

110
Q

What is the most important feature for recognising the hair cycle phase?

A

The dermal papilla

It’s size (most prominent in anagen and within hair bulb) and position in the hair follicle and location in the dermis or subcutis

111
Q

What is the only mesenchymal component of the hair follicle?

A

Dermal papilla

112
Q

Trichohyaline granules are present in the outer root sheath in which portion of the hair follicle?

A

Inferior

113
Q

What is Adamson Fringe?

A

Where both layers of the outer root sheath are cornified (where the isthmus starts!)

114
Q

Which granules are visible in the infundibulum?

A

Keratohyalin granules

There are no granules in the isthmus!
Trichohyalin granules are present in the inferior portion

115
Q

Which part of the hair follicle contains glycogenated cells in the outer root sheath?

A

Lower isthmus and suprabulbar portion of inferior

116
Q

Why do you see comedones in HAC?

A

Thinned collagen is unable to support the hair follicle and it dilates

117
Q

What is a typical epidermal feature of histiocytomas?

A

Rete ridges

118
Q

Do plasma cell tumours or histiocytomas form cords?

A

Histiocytomas form cords, particularly noticeable at the superficial dermis

Plasma cell tumours often form dense sheets

119
Q

What shape can nuclei be in histiocytomas?

A

Round to oval and often indented (like a potato!)

120
Q

Some plasma cell tumours contain accumulations of which eosinophilic substance? Which special stain can be used to help identify the substance?

A

Amyloid

Congo red

121
Q

Which type of furunculosis most often contains haemorhage?

A

Post grooming furunculosis

122
Q

Biopsy of a cat pinna; what is the most likely diagnosis?

A

Cystadenomatosis

123
Q

Why do lesions of atypical mycobacterial infection in cats feel firm?

A

Fibroplasia

124
Q

From a cutaneous nodule in a ferret, what is the diagnosis?

A

Fungal pyogranuloma (dermatophytic pseudomycetoma)

125
Q

What is Dunstan’s blue line?

A

Gram-positive cocci within superficial layers of keratin accompanied by granular basophilic cellular debris

126
Q

How do you differentiate candidiasis from superficial pustular dermatophytosis?

A

Culture

127
Q

What is the ‘usable artifact of Stannard’?

A

Artifactual dermal–epidermal separation at the margin of the specimen. Only tissue weakened through the dermal–epidermal junction will separate in this manner during processing, and consequently this ‘usable artifact of Stannard’ is valid evidence of interface damage

128
Q

What is ‘red spaghetti of Walder’?

A

Eosinophilic, wavy elastin fibrils in the superficial dermis seen in erythema ab igne

129
Q

How many nuclei can be present in an epidermal syncytial giant cell in FeLV giant cell dermatosis?

A

Up to 30!

Sarah - Dermatohistopathology (6 decks)

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