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