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Pathology of the
Integumentary System
Histopathology Lab (web)
Paul Hanna Fall 2017
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Slide #161 & #162
Signalment:
• Cocker spaniel, 1 yr-old, male
Clinical History:
• patchy area of alopecia on left side of neck
• Woods lamp negative
• submitted fresh hairs from lesion and punch biopsy of lesion
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Area where skin is minimally
affected; ie normal appearing
follicles & glands
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Some areas show hypercellularity (inflammatory
cells) surrounding follicles & within follicular lumina
At higher magnification you can see inflammatory cells
surrounding and within follicular wall / lumen
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In other areas the inflammation has entirely destroyed the follicular walls,
leaving just hair shafts surrounded by inflammation (ie furunculosis) Higher magnification of area with furunculosis: note degenerating
hair shaft surrounded by inflammation (asterix)
*
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Perifolliculitis Folliculitis Furunculosis
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At higher magnification, see myriads (= too
numerous to count) of arthrospores around
and hyphae within degenerating hair shaft
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Arthrospores and hyphae staining bright red with PAS stain
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Slide #161 & #162
Morphologic Features:
• intense inflammatory cell infiltrate surrounding, infiltrating or disrupting follicles
• inflammatory cells are a mixture of neutrophils, lymphocytes, plasma cells and
macrophages
• degenerating hairshafts are infiltrated and surrounded by arthrospores & hyphae
(stain pale blue on H&E stain and bright red with PAS stain).
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Slide #161 & #162
Morphologic Diagnosis:
Severe, multifocal, pyogranulomatous perifolliculitis / folliculitis / furunculosis with
intralesional arthrospores
Comment:
• lesions are diagnostic of dermatophytosis (ringworm)
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Slide #165
Signalment:
• 3 yr-old, female, Golden retriever
Clinical History:
• dog is mildly pruritic
• pustules and epidermal collarettes evident on abdomen and flanks
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Note, pustules and epidermal collarettes
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Histopath pattern = Intraepidermal pustular dermatitis
Intraepidermal pustule (intracorneal)
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Exocytosis of neutrophils, ie migration of neutrophils from dermis, through epidermis, into pustule
Intraepidermal pustule (intra- to subcorneal)
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Intraepidermal (intra- to subcorneal) pustule containing
degenerate neutrophils
Exocytosis of neutrophils, ie migration of neutrophils from dermis into pustule
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Slide #165
Morphologic Features:
• subcorneal / intracorneal pustule containing neutrophils (mostly degenerate) and
occasional coccoid bacteria
• epidermis shows moderate regular hyperplasia & frequent exocytosis of neutrophils
• superficial dermis shows edema, hemorrhage and perivascular to interstitial infiltrate
of moderate numbers of neutrophils
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Slide #165
Morphologic Diagnosis:
Intraepidermal pustular dermatitis
Comment:
• consistent with pyoderma (likely Staphylococcus)
• rule-out:
i) pemphigus foliaceous (no acantholytic cells), etc
ii) underlying skin disease (eg HS’s, ectoparasites, etc)
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Slide #166
Signalment:
• dachshund, 3 months, female
Clinical History:
• dog has been severely pruritic
• treated 3 times (steroids?) - no response
• severe alopecia, scaling and lichenification on limbs (esp elbows & hocks) and to
a lesser degree on ear margins
• patchy alopecia & scaling throughout most of the rest of the coat
• numerous papules on ventral abdomen
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Pattern = Hyperplastic perivascular / interstitial
dermatitis
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Section of mite within epidermal tunnel;
note prominent cuticular spines Note infiltrate of eosinophils adjacent to
tunnel containing mite.
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Slide #166
Morphologic Features:
• at low power: prominent crusting and epidermal hyperplasia
• at medium / high power:
cellular crust - keratin admixed with degenerate inflammatory cells
epidermal hyperplasia – with occasional intraepidermal “tunnels” containing mites
superficial dermis – edema & pervascular / interstitial infiltrate of eosinophils and monuclear
inflammatory cells
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Slide #166
Morphologic Diagnosis:
Hyperplastic perivascular dermatitis with marked cellular crusting & intralesional
mites (consistent with Sarcoptes sp)
Comment:
• morphology of mites (cuticular spines) diagnostic for sarcoptic mange
• if don't see mites, consider sarcoptes and other ectoparasites &/or hypersensitivities
(eg flea allergy dermatitis)
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Slide #167
Signalment:
• 4 yr-old, spayed female, dog
Clinical History:
• chronic bilateral (symmetric) alopecia with hyperpigmentation and comedones
• skin is very thin
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Note comedones which are more
obvious on closer inspection (inset)
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subcutis
underlying
skeletal muscle
skin is very thin
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Dermis is very thin and follicles appear small and abnormal
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Hyperkeratosis &
hyperpigmentation
Arrested (catagen / telogen)
& atrophic follicles atrophic sebaceous glands
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Histopathologic Pattern = Atrophic dermatosis
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Hyperkeratosis with increased melanin Epidermis reduced to 1 cell layer in some areas
Dilated, atrophic follicle filled with keratin
(ie histopathologic equivalent of comedo) Atrophic sebaceous gland
= features
suggestive of
Cushings
Atrophic follicles
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Slide #167
Morphologic Features:
• low power: thin dermis and small irregular follicles (catagen / telogen)
• medium / high power:
hyperkeratosis with excess pigment
atrophy of non-cornified epidermis (often 1 cell layer!)
sebaceous gland atrophy
hair cycle arrest (no anagen follicles), follicular atrophy / dilation / keratosis
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Slide #167
Morphologic Diagnosis:
Atrophic dermatosis
Comment:
• history and lesions are characteristic of an endocrine dermatosis
• some of the gross (ie thin skin & comedones) and histopathologic (epidermal /
dermal atrophy) features, are suggestive of hyperadrenocorticism
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