Pathology of the Integumentary System, Pt. 5 Flashcards
What are the 2 types of nodular/diffuse dermatitis? What are the 3 possible inflammatory infiltrates and their cause?
- infectious**
- noninfectious
- neutrophils —> bacteria
- eosinophils —> parasites, eosinophilic granuloma
- histiocytes (chronic granuloma/pyogranuloma) —> mycobacteria, fungi, foreign body
Nodular/diffuse dermatitis, histology:
How does nodule/diffuse dermatitis present grossly?
nodular or plaque-like lesions that may be alopecic, ulcerated, or draining
What causes canine leproid granuloma? What breeds are most commonly affected?
novel mycobacterial species
short-coated large breeds, like Boxers
How does canine leproid granuloma present grossly?
single to multiple well-circumscribed, firm, nonpainful dermal nodules on pinnae (ONLY)
What is seen histologically in canine leproid granuloma?
pyogranulomatous dermatitis with intralesional acid-fast positive bacteria
What are cutaneous lesions from deep/systemic fungal infection secondary to? How does infection begin?
systemic infection from lungs, eyes, and bones
ingestion or inhalation from contaminated soil
- geographical distribution
What are 4 examples of fungi that cause deep/systemic fungal infection?
- Cryptococcus neoformans
- Histoplasma capsulatum
- Blastomyces dermatitidis
- Coccidioides immitis
Deep/systemic fungal infection, gross lesions:
nodular, plaque-like; ulcerative, alopecic
Deep/systemic fungal infection, histology:
What is pythiosis?
ulcerative lesions with fistulous tracts, along with pale yellow coral-like concretions found in sinus tracts (kunkers) caused by Pythium insidiosum, an aquatic dimorphic water mold
How does the presentation of pythiosis compare in dogs and horses?
DOG: GI > skin
HORSE skin > GI
- limbs, ventral thorax, abdomen
What is seen on histology of pythiosis?
granulomatous and eosinophilic inflammation and granulation tissue
- + peripheral eosinophilia
What causes Leishmaniasis? How is it transmitted?
Leishmania infantum —> obligate intracellular protozoa
bite of sandfly
- zoonotic!
What are the cutaneous and systemic symptoms of Leishmaniasis?
CUTANEOUS: alopecia, ulcers, nodules, and exfoliative dermatitis on the muzzle, periorbital and aural regions; onychongryphosis
SYSTEMIC: hyperproteinemia with hypergammaglobulinemia and hypoalbuminemia
Leishmaniasis, histology:
What causes Habronemiasis? What is its pathogenesis? When is infection most common?
(summer sores in horses)
Habronema muscae nematode transmitted by flies
- nematode passed in feces
- ingested by fly maggots
- deposited onto horse in the medial canthus of eye and prepuce by host fly
summer and early fall, when flies are active
What is seen histologically in Habronemiasis?
granulomatous and eosinophilic inflammation around nematode larvae
What are 2 examples of noninfectious diffuse/nodular dermatitis?
- sterile granulomatous dermatitis and lymphadenitits
- eosinophilic granuloma
What is sterile granulomatous dermatitis and lymphadenitis? In what dogs is it most common?
juvenile cellulitis, puppy strangle
mostly young Golden retrievers, dachshunds, labrador retrievers, and Gordon setters
What gross lesions are seen in granulomatous dermatitis and lymphadenitis? What are some other clinical signs?
facial swelling, papules, and pustules affecting the periocular skin, muzzle and pinnae
- fever
- lethargy
- hyporexia
- lymphadenomegaly
What is seen histologically with granulomatous dermatitis and lymphadenitis?
nodular pyogranulomatous dermatitis lacking any infectious agents
What is the cause of granulomatous dermatitis and lymphadenitis? What does it commonly respond to?
cause unknown
immunosuppressive drugs
What are the 3 manifestations of eosinophilic granuloma complex?
- eosinophilic plaque
- indolent ulcer
- eosinophilic granuloma
What is the characteristic of eosinophilic granuloma complex on histology?
flame figure of hyalinized collagen
- + eosinophils
What is panniculitis? What are some probable causes?
inflammation of the subcutis
- trauma
- post injection
- post surgery
- foreign body
- infectious disease (must rule out)
- pancreatic disease (lipase release)
- vitamin E deficiency
- immune-mediated
- idiopathic
What type of panniculitis is most commonly has idiopathic cause?
sterile nodular panniculitis more common in dogs
Panniculitis, histology:
inflammatory cells infiltrate subcutis
What are 2 major lesions characteristic of panniculitis?
- nodules
- draining tracts
What is sterile nodular panniculitis? In what dogs is it most common?
(sterile pyogranulomatous dermatitis and panniculitis; sterile granuloma/pyogranuloma syndrome)
idiopathic condition with dermal or subcutaneous nodules with drainage or ulcers mostly found on the trunk (commonly in association with fever, anorexia, and concurrent disease)
Dachshunds
How is sterile nodular panniculitis diagnosed? What type of treatment does it typically respond to?
must rule out infectious disease first with negative tissue culture and special stains for bacteria, fungi, and mycobacterium
immunomodulatory or immunosuppressive medications
What is seen histologically in sterile nodular panniculitis?
pyogranulomatous dermatitis and panniculitis
What are the main 3 features of atrophic dermatoses (noninflammatory alopecia? What are 3 causes?
- follicular atrophy (telogen) with follicular keratosis
- sebaceous atrophy
3 epidermal +/- dermal atrophy - endocrine dermatopathy***
- ischemia
- feline acquired skin fragility
Atrophic dermatoses (noninflammatory alopecia), histology:
How does endocrine dermatoses present?
bilateral symmetrical alopecia with hyperpigmentation, epidermal and dermal thining, and a rough, dry, and dull coat
- minimal inflammation —> scaling with secondary infection
How is endocrine dermatoses diagnosed?
clinical, gross, and histological lesion are rarely specific —> diagnosis based on clinical and histological features + clinical testing for hormonal deficiency/excess
What 6 conditions are responsible for endocrine dermatoses?
- hypothyroidism (T4)
- hyperadrenocorticism
- hyperestrogenism
- hyposomatotropism (dwarfism)
- hypersomatotropism
- alopecia X
What is hypothyroidism? What dermal lesions does it cause? In what dogs is it most common?
primary thyroid dysfunction caused by lymphocytic thyroiditis or idiopathic thyroid atrophy
bilateral symmetrical alopecia, thickened and droopy facial skin from myxedema, and alopecia of the entire tail (rat tail)
middle-aged dogs
What are 3 causes of hyperadrenocorticism (HAC)?
- pituitary-dependent
- adrenal-dependent
- iatrogenic
What are 6 common dermal lesions caused by hyperadrenocorticism (HAC)?
- bilaterally symmetrical alopecia of the trunk
- pendulous abdomen
- hyperpigmentation
- telangiectasia
- comedones (keratin accumulation)
- calcinosis cutis (most common in iatrogenic form)
What is alopecia X most common in? How does it present?
plush-coated breeds (Pomeranians, Chow Chows, Husky)
bilateral symmetrical alopecia with hyperpigmentation on the trunk, and caudal thighs, sparing the head and distal extremities
What are the main 2 causes of hyperestrogenism? How does it present?
- SPONTANEOUS: testicular sustentacular cell (Sertoli cell) tumor, ovarian cyst, ovarian neoplasia (increases estrogen levels)
- EXOGENOUS: transdermal estradiol gel
bilaterally symmetrical alopecia and hyperpigmentation, with gynecomastia or vulvar enlargement
What is cutaneous vasculitis? What are 4 common causes?
inflammation targeting walls of venules or arterioles
- bacterial infection (Ehrlichiosis, Rocky Mountain spotted fever)
- bacterial septicemia (Erysipelothrix rhusiopathiae)
- immune-mediated disease
- drug associated
What are the 4 most common lesions associated with cutaneous vasculitis?
- edema
- erythematous macules
- petechiae
- ecchymoses
Other than edema, erythematous macules, petechiae, and ecchymoses, what can cutaneous vasculitis also lead to?
ulceration of distal extremities (pinnae, toes, tail tip) with or without sloughing of tissue
What causes swine erysipelas (diamond skin disease)? What are the 3 forms? What kind of pigs does it usually affect?
Erysipelothrix rhusiopathiae
- acute (septic/fatal/cutaneous lesions)
- subacute
- chronic
growing and adult swine
What causes cutaneous lesions to occur during swine erysipelas (diamond skin disease)? What lesions are seen?
septicemia —> bacterial emobolization to the skin —> vasculitis —> thrombosis, ischemia, infarction
multifocal, red to purple rhomboidal (diamond), slightly raised skin lesions
What are 4 cutaneous tumor-like proliferations? What are the 3 types of tumors?
- viral plaque
- cyst
- hamartoma
- cutaneous horn
- epithelial (adenoma, carcinoma)
- mesenchymal (-oma, -sarcoma)
- round cell
What diagnostic is commonly used on growths to see if it is a cancerous growth? How do the different types of tumors show?
FNA for cytology
- epithelial: cell adhesions remain
- mesenchymal: individualized spindles
- round cell: individualized, large, round
Tumor-like lesions:
What are the major presentations of Papillomaviral disease in dogs?
- oral papillomatosis (cauliflower-like)
- cutaneous papillomas
- squamous cell carcinomas
- pigmented viral plaques
What are the 2 most common things seen on histology of viral papilloma?
- viral cytopathic effect - grey cytoplasm
- intranuclear viral inclusion bodies
What causes papillomavirus in cattle? At what age is infection most common? How is it transmitted?
bovine papillomavirus 1-13
young cattle <2 years old
direct or indirect contact
How does papillomavirus present in cattle?
horny, dry, cauliflower-like masses (warts) on the head, neck, shoulders, teats, and penis
What is one of the most common malignant neoplasms in cats? What causes it in different parts of the skin?
(epithelial) squamous cell carcinoma
UV light = lightly pigmented skin
papillomavirus = pigmented skin
What is the most common skin neoplasm of equids? What causes it?
(mesenchymal) equine sarcoid
BPV-1, 2, and 12
What is equine sarcoid? In what areas does it frequently develop?
locally aggressive, nonmetaplastic, fibroblastic skin tumors that present as nodules, plaques, verrucous masses on the head, periocular region, ears, limbs, and prepuce
- areas with previous trauma
- recurs after surgical excision
What causes injection site-associated sarcoma? What is prognosis like?
vaccines, injections of foreign material, trauma, and microchip implantations
locally aggressive with a high rate of local recurrence —> poor prognosis
What kind of tumors are injection site-associated sarcomas?
mesenchymal —> fibrosarcomas**, osteosarcoma, rhabdomyosarcoma, lymphoma
What are the most common pigmented nodules?
RED: hemangioma or hemangiosarcoma
BLACK: melanocytoma or melanoma
What acronym is used to list the types of round cell neoplasia? How are they diagnosed?
L = lymphoma
Y = transmissible venereal tumor
M = mast cell tumor
P = plasma cell tumor
H = histiocytoma
perform a FNA and do cytologic exam
What kind of neoplasm is histiocytoma? What do they look like? What age animals are mostly affected?
round cell neoplasia of Langerhans cells
dome-shaped
young dogs
What is the prognosis of histiocytomas?
good! —> undergoes spontaneous immune-mediated regression
What is the most common skin tumor in dogs? How does it typically present?
(round cell) mast cell tumors
alopecic, solitary to multiple, erythematous and edematous nodules on the trunk, extremities, and head
What does the prognosis of mast cell tumors depend on?
histoligcal grades —> submit for biopsy!
How does canine cutaneous epitheliotropic lymphoma present? In what animals is it most common? Why is prognosis so poor?
generalized scaling, ulcers, nodules and depigmentation of the lips and nasal planum
older dogs
tends to metastasize to lymph nodes, which leads to systemic spread
What is characteristic of canine cutaneous epitheliotropic lymphoma?
neoplastic CD3+ T-cells infiltrated epidermis/dermis
