Dermatologic manifestations of systemic disease Flashcards
Outline calcinosis cutis
Dystrophic calcification of the skin
- HAC (naturallyoccurring and iatrogenic)
- Clinical diagnosis in cases with compatible Hx, characteristic skin appearance and location
- Erythematous papules, gritty plaques, ulceration, haemorrhagic crusts +/ 2ary infections
- The grittyness is pathogmonic
- Areas of friction
- Dorsal cervical, axillary, inguinal, MM, tongue
What would be the ddx for
- Paw pad hyperkeratosis & perioral crusting
dermatitis, Lethargy, PU/PD
- Superficial Necrolytic Dermatitis (hepatocutaneous syndrome)
- Pemphigus foliaceus
- Adverse Drug Reaction
- Erythema Multiforme
- Contact hypersensitivity/irritant
- Zincresponsive dermatitis
What do you see on skin biopsy in a case of superficial necrolytic dermatitis?
‘French flag’ pattern
- Pink (parakeratotic hyperkeratosis)
- White (keratinocyte pallor degeneration)
- Blue (basal cell hyperplasia)
What is superficial necrolytic dermatitis?
- Uncommon skin condition associated to systemic metabolic diseases
- Mostly 2ary to metabolic hepatic disease (cirrhosis, neoplasia, hepatic lipidosis, phenobarbital tx)
- Unique liver appearance on US (‘honeycomb’ or ‘Swiss cheese’)
- Other names: Hepatocutaneous Syndrome, Necrolytic Migratory Erythema
- Small number of cases 2ary to glucagonomas (most common cause in humans)
- Older dogs
- Footpad hyperkeratosis with fissures and crusting dermatitis at pressure points, mucocutaneous junctions and paws.
- PU/PD common
How do you treat superficial necrolytic dermatitis?
- Generally guardedpoor prognosis
- Parenteral aminoacid infusions, EFAs, high quality protein diets
- Manage 2ary pyoderma and/or Malassezia spp. overgrowth
- Potentially better prognosis if glucagon producing neoplasia identified and removed prior to metastases
What are the main non-neoplastic skin disorders associated with internal malignancy?
- Feline Thymoma associated exfoliative dermatosis
- Feline Paraneoplastic alopecia
- Testicular tumours
- Paraneoplastic pemphigus
How does Feline thymoma associated exfoliative dermatosis present?
- Generalised exfoliative dermatitis with marked scaling
- Immunemediated mechanism of graftversushost type reaction suspected
- Generally nonpruritic
- 2ary bacteria and Malassezia infections ++++
What are the ddx for generalised exfoliative dermatitis with marked scaling?
- Dermatophytosis
- Cheyletiellosis
- Erythema multiforme
- Epitheliotropic T-cell lymphoma
How do you dx/manage Feline thymoma associated exfoliative dermatosis?
- Dx: histopathology of skin lesions, thoracic imaging
- Surgical resection of thymoma results in resolution of dermatosis
- Feline non thymoma associated exfoliative dermatosis clinically and histopathologically identical
- Response to immune suppressive therapy
Outline feline paraneoplastic alopecia
- 2ary to pancreatic adenocarcinoma (others uncommonly)
- Bilaterally symmetrical, ventrally distributed alopecia
- Shiny skin (no fragility)
- Nonpruritic, unless 2ary Malassezia +++ common – brown greasy accumulations
- Dry, scaly or fissured footpads
- Skin lesions the 1st clinical sign noticed, no concurrent systemic signs
- Characteristic skin histopathology Æ recommend abdominal imaging
- Prognosis grave (metastasis)
What skin signs may you see with canine testicular tumours?
- Linear preputial erythema with hyperestrogenism
- Tail gland and perianal gland hyperplasia with hyperandrogenism
Outline paraneoplastic pemphigus
- Very rare (3 dogs, 1 cat)
- Reported with thymoma, thymic lymphoma and splenic sarcoma
- Severe autoimmune blistering skin disease
- Autoantibodies against several desmosomal components
- Erosions, ulcers on mucosae, mucocutaneous junctions +/ haired skin
- Dx: characteristic skin histopathology Æ look for internal neoplasia
- Suprabasal clefting (as seen with PV)
- Lymphocytic interface dermatitis with basal and suprabasal apoptotic keratinocytes (as seen with EM)
- Grave prognosis
- Management of the underlying neoplasia
- No response to immunesuppressive therapy
What would be the ddx for progressive generalised nonpruritic alopecia and scaling, PU/PD and weight loss, Generalised peripheral lymphadenopathy
Cutaneous lymphoma SLE Pemphigus foliaceus Sebaceous adenitis Endocrinopathy Anagen/telogen effluvium Infection Leishmania
Which viruses may show skin signs?
Leishmaniosis and other protozoal infections
Subcutaneous and deep mycoses (cryptococcosis, histoplasmosis, aspergillosis, etc)
Canine distemper virus
FIV/FeLV
Feline Poxvirus
Feline herpesvirus
FIP
What is canine sterile nodular panniculitis
Single or multiple deep subcutaneous nodules (+/ draining tracts, ulceration)
Trunk, head, neck, generalised
Inflammation of panniculus
Adult dogs (can also be seen in young), any breed
Dachshunds, Poodles, Australian shepherd dogs, Brittany spaniels, Chihuahuas, Dalmatians, Pomeranians
Diagnosis of exclusion
Rule out infectious and other noninfectious causes of nodular skin disease
Full thickness skin biopsies for histopathology + special stains + bacterial, fungal, and mycobacterial cultures
Immunosuppressive treatment with oral GC +/ ciclosporin, tetracycline antibiotic and niacinamide
What is canine renal cystadenocarcinoma and nodular dermatofibrosis?
Rare inherited syndrome of GSD (mainly)
Nodular dermatofibrosis (ND): cutaneous benign collagenous nodular disease
Multiple firm dermal and subcutaneous nodules affecting extremities +/ other locations
Bilateral renal neoplasia develop months to years after cutaneous nodules
Cystadenocarcinoma or cystadenoma or uterine leiomyoma (less common)
Haematuria, PU/PD, weight loss, vomiting
Nodular dermatofibrosis historically considered as a paraneoplastic syndrome
TGFb1 production by renal tumour cells
FLCN gene mutation encoding folliculin (tumour suppressor function suspected)
Autosomal dominant transmission
How does coronavirus become FIP?
a mutation occurs, resulting in the ability of the virus to replicate within macrophages, and mutated viruses are disseminated from the intestine by macrophages throughout the body. Clinical signs result from the cat’s own immune reaction. FIP is an immune complex disease involving virus, antiviral antibodies and complement
How does alopecia in curly coat retrievers present?
Young adults
follicular dysplasia
What is syndrome I of zinc responsive dermatitis
identified in Siberian huskies, Alaskan malamutes, and occasionally other breeds. Affected dogs typically present with erythema followed by variable alopecia with fine silver scale that becomes adherent or develops into crusting involving the mucocutaneous junctions of the face (periocular, perioral), pressure points (elbows, hocks), and footpad margins
Diagnosis is based on signalment, typical cutaneous lesions, and histopathology of skin biopsies that shows marked follicular and epidermal parakeratotic hyperkeratosis. Therapy requires Zn supplementation with a recommended dosage of 2–3 mg/kg of elemental Zn in the form of zinc sulfate, zinc gluconate, or zinc methionine. There was not a detected difference between the different Zn salts in one study Clinical signs are typically improved within 4–6 weeks.
What is zinc repsonsive dermatitis syndrome II?
occurs in rapidly growing puppies that are being fed a poor-quality dog food or are being oversupplemented with calcium. These dogs are thought to have a relative Zn deficiency caused by a combination of low Zn intake and calcium or cereal phytate binding of Zn. Affected dogs have generalized crusting plaques with extensive crusting and fissuring of the foot pads. Diagnosis is based on compatible history, clinical signs, and histopathology (similar to those of syndrome I). Response to Zn supplementation is dramatic but is not needed once the dog has reached maturity, unlike most syndrome I dogs. Many dogs will respond to a higher quality diet.
What is lethal acrodermatitis?
autosomal recessive disease seen in white bull terriers.
The homozygously affected puppies show clinical signs in the first few weeks of life and have a median survival of 7 months, typically succumbing to bronchopneumonia and sepsis. Bull terriers that are heterozygously affected may have increased risk for pyoderma.
progressive crusting dermatitis of the distal extremities and mucocutaneous junctions. Abnormal keratinization of paw pads can result in splaying of the feet. Claw dystrophy and paronychia may also be present.
There is no therapy
How do cutaneous xanthomas present?
present as multiple pale yellow to white plaques, papules, or nodules with erythematous borders. They often are located on the head, particularly the preauricular area or pinnae. Lesions can develop in paw pads and over boney prominences on limbs
occur when there is underlying hereditary defects in lipid metabolism or acquired dyslipoproteinemia secondary to diabetes mellitus, or use of megestrol acetate.
How do you ix/ tx cutaneous xanthomas
Histologic evaluation of skin biopsies shows large foamy macrophages and giant cells. Serum biochemistry evaluations for diabetes mellitus, hypercholesterolemia, and hypertriglyceridemia should be obtained. Feeding of a low-fat diet and identification and correction of the underlying disturbance in lipid metabolism is recommended for patients that have had cutaneous xanthomas identified.
How may deep or systemic mycoses appear?
blastomycosis, coccidioidomycosis, cryptococcosis, histoplasmosis, aspergillosis
papules, nodules, draining tracts, and ulceration and typically result from hematogenous dissemination of the fungal organism to the skin.
Nasal aspergillosis can cause depigmentation and ulceration often beneath the nares as a result of a drainage board effect from the chronic nasal discharge
How can distemper affect the skin?
Hard pad disease
Dogs develop excessive keratinous material on the foot pads and nasal planum
How can feline herpes virus affect the skin?
ulcerative dermatitis typically involves the dorsal muzzle, but lesions may extend to involve the nasal planum. Cats do not have to have concurrent ocular or upper respiratory tract signs. Histologically, the lesion is a necrotizing, ulcerative dermatitis most often with a concurrent marked eosinophilic inflammation, but the inflammatory pattern may be strongly neutrophilic in some cases
What is SLE?
Systemic lupus erythematosus (SLE) is a multisystemic autoimmune disease. The collie, Shetland sheepdog, German shepherd dog, spitz, and poodle are reported to be at increased risk. Skin disease occurs in less than 20% of SLE cases. Fever, polyarthritis, protein-losing nephropathy, anemia, and thrombocytopenia are more common clinical signs seen with SLE. Organ-specific and non–organ-specific autoantibodies target a variety of tissue antigens in SLE. Resultant tissue damage occurs when there is immune complex deposition (as occurs in glomerulonephritis) or can occur because of direct cytotoxic effects or cell-mediated immunity.
What cutaneous lesions may be seen with SLE?
erythema, scaling, crusting, depigmentation, alopecia, and ulcerations. Lesions often involve the face, pinnae, and distal extremities. Lesions may be present on mucocutaneous junctions and within the oral cavity. Ulcers and erosions are rarely diagnostic lesions to biopsy, because an intact epidermis is needed to make a definitive diagnosis. The histopathologic findings are variable, but classic lesions include apoptosis of basal cells and basal cell vacuolation, which lead to dermo-epidermal separation and consequent ulceration.
How does erythema multiforme present?
often pleomorphic with an acute onset of erythematous plaques and macules that often become annular or serpiginous as they coalesce or they may appear targetoid. Progression to ulcerations is common, and lesions may become variably crusted. Lesions often are generalized but are most commonly found on the ventrum, axillae, inguinal region, mucocutaneous junctions, oral cavity, and pinnae. Biopsies should be obtained from areas of erythema without ulceration or crusting because an intact epidermis is needed for the diagnosis. Histologically, apoptosis with lymphocyte satellitosis is the characteristic microscopic lesion of EM.
What may lead to an unkept haircoat in cats?
Hyperthyroidism
Reduced ability to groom - OA, obesity, oral pain, lethargy, malaise
Nutritional deficiencies
When may cats get demodex
diabetes mellitus, FIV, feline leukaemia virus (FeLV) infection, systemic lupus erythematosus (SLE), Mycoplasma haemofelis infection, hyperadrenocorticism, and systemic or topical inhalant (fluticasone) steroid therapy
What is FeLV giant cell associated dermatitis
very rare scaling, alopecic and crusting dermatitis, with some pruritus
The head is generally affected (pinnae, preauricular, perioral), along with variable involvement of feet, footpads and other mucocutaneous areas
Histopathology changes in skin biopsies reveal characteristic ballooning of epidermal and follicular epithelial cells (giant cells). FeLV infection in a cat with unexplained, poorly responsive or atypical pruritic dermatitis may raise suspicion for this differential
Outline cutaenous horns in cats
conical or cylindrical collections of keratin – are rare, and most often reported on the footpads, although they occasionally arise on the nasal planum or eyelids. They may be associated with FeLV infection (multiple horns), or may constitute localised cutaneous disease only (single or multiple, due to papillomavirus, actinic keratosis, squamous cell carcinoma [SCC] in situ, SCC, keratinising acanthoma). Screening for FeLV status is warranted in cats presenting with cutaneous horns
What are the most likely ddx for multifocal erosions and ulceration in a cat?
Erythema multiforme, paraneoplastic pemphigus, drug reactions (no recent history), cutaneous vasculitis and systemic lupus erythematosus
How do SCCs in situ present?
middle-aged to older cats of varying breeds as localised single or multifocal melanotic scaly plaques, progressing to ulcerative and crusted plaques and nodules
Some forms are associated with papilloma virus
What is erythema multiforme?
characterised by multifocal keratinocyte death (apoptosis), resulting in multifocal to coalescing areas of erythema to ulceration of the skin and mucosa. There is a spectrum of severity, from mild erythematous lesions to full thickness ulceration, affecting localised to extensive skin and mucosal areas. Classical ‘target’ lesions, consisting of erythematous macules that spread peripherally and clear centrally, may be present.
Concurrent malaise and pyrexia are common
What are the main causes of infectious nodules in cats?
Nocardia Leprosy Mycobacteria Environmental fungi Protozoa (e.g. leishmania)
