Post on 04-Jun-2019
Pathology of the
Integumentary System
Histopathology Lab (web)
Paul Hanna Fall 2017
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
Area where skin is minimally
affected; ie normal appearing
follicles & glands
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
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)
*
Perifolliculitis Folliculitis Furunculosis
At higher magnification, see myriads (= too
numerous to count) of arthrospores around
and hyphae within degenerating hair shaft
Arthrospores and hyphae staining bright red with PAS stain
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).
Slide #161 & #162
Morphologic Diagnosis:
Severe, multifocal, pyogranulomatous perifolliculitis / folliculitis / furunculosis with
intralesional arthrospores
Comment:
• lesions are diagnostic of dermatophytosis (ringworm)
Slide #165
Signalment:
• 3 yr-old, female, Golden retriever
Clinical History:
• dog is mildly pruritic
• pustules and epidermal collarettes evident on abdomen and flanks
Note, pustules and epidermal collarettes
Histopath pattern = Intraepidermal pustular dermatitis
Intraepidermal pustule (intracorneal)
Exocytosis of neutrophils, ie migration of neutrophils from dermis, through epidermis, into pustule
Intraepidermal pustule (intra- to subcorneal)
Intraepidermal (intra- to subcorneal) pustule containing
degenerate neutrophils
Exocytosis of neutrophils, ie migration of neutrophils from dermis into pustule
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
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)
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
Pattern = Hyperplastic perivascular / interstitial
dermatitis
Section of mite within epidermal tunnel;
note prominent cuticular spines Note infiltrate of eosinophils adjacent to
tunnel containing mite.
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
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)
Slide #167
Signalment:
• 4 yr-old, spayed female, dog
Clinical History:
• chronic bilateral (symmetric) alopecia with hyperpigmentation and comedones
• skin is very thin
Note comedones which are more
obvious on closer inspection (inset)
subcutis
underlying
skeletal muscle
skin is very thin
Dermis is very thin and follicles appear small and abnormal
Hyperkeratosis &
hyperpigmentation
Arrested (catagen / telogen)
& atrophic follicles atrophic sebaceous glands
Histopathologic Pattern = Atrophic dermatosis
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
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
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