Malassezia Dermatitis Flashcards
(31 cards)
What is Malassezia pachydermatis? What stains are used for diagnosis?
lipid-dependent, lipophilic yeast (lacks fatty acid synthase) that is a normal inhabitant of canine skin –> broad-based, budding, round, peanut-shaped
- Diff-Quik
- methylene blue
- Wright’s stain
- Gram +
- silver stain
What 4 factors add to pathogenicity of Malassezia?
- environment - humidity, temperature
- immunity - age, disease
- breeds - Basset Hound, Boxer, Dachshund, American Cocker Spaniel
- concurrent disease - atopy
+/- skin lipid content drives species composition
What diseases are associated with Malassezia dermatitis in dogs and cats?
- ALLERGIES - atopy, adverse food reactions, flea allergy
- ENDOCRINE - hypothyroidism, Cushing’s, DM
- CORNIFICATION - seborrhea, epidermal dysplasia (WHWT)
- SYSTEMIC - liver/renal disease
systemic illness, allergies
What 5 pathogenic mechanisms do Malassezia contain?
- activation of alternate pathway of complement
- hypersensitivity to fungal allergens - IgE, IgG
- produces zymosan and phospholipase that contribute to inflammation and pruritus
- produces a biofilm
- symbiotic relationship with staphylococci
Where in the skin will Malassezia infection be found?
outer layer of skin –> enzymes absorbed deeper
- not normally in follicles or deeper
What are 3 key historical features of Malassezia dermatitis? What historical complaints are associated?
- severe progressive pruritis
- generally non-seasonal - heat exacerbation, wet weather, snow
- partially responsive to glucocorticoids
licking feet, rubbing face, perianal pruritus, otitis externa, weight loss –> seems like atopy out of control
What are the 4 major differential diagnoses for intense pruritus?
- scabies
- Malassezia dermatitis
- flea allergy dermatitis
- familial seborrhea - Cocker Spaniel
What are 5 lesions associated with Malassezia dermatitis?
- erythematous scaling and crusting
- lichenified, hyperplastic, hyperpigmented skin
- alopecia
- generalized enlarged LNs
- otitis
Malassezia dermatitis:
scaling and crusting
Malassezia dermatitis:
lichenification, alopecia
- swab edges, not thick skin
Malassezia dermatitis:
thin-skinned areas commonly affected –> inguinal, axilla, toe webs
Malassezia dermatits:
classical - interdigital skin, dorsal AND ventral
Malassezia, WHWT:
- depressed, lethargic
- thickened skin
- odor
- otitis
- WHWY armadillo syndrome
Malassezia, Himalayan:
thick, waxy debris
What are the two major trouble areas associated with Malassezia dermatitis?
- facial/lip folds
- paws - claw folds, interdigital skin, waxy buildup full of yeast common at nail beds
+/- thin-skinned areas
What cat breed is predisposed to developing Malassezia dermatitis? What is it associated with? What 3 species are most commonly seen?
Devon Rex –> allergy, seborrhea, systemic illness
- M. pachydermatis (50%)
- M. furfur (40%)
- M. sympodialis (10%)
What 7 steps are recommended while diagnosing Malassezia dermatitis?
- dermatological history
- PE and dermatologic examinations
- dermatology data base
- allergy testing - atopy, food
- CBC/chem/UA
- endocrine function tests
- immune system evaluation
What 3 locations should be sampled for Malassezia dermatitis? What areas are avoided?
- lip folds
- dorsal/ventral interdigital spaces
- axillary, perivulvar, perianal, and facial folds
severely lichenified skin
Malassezia cytology scale:
most useful for quality control, NOT if treatment is indicated
Malassezia:
Diff-Quik stains all stages
What secondary condition commonly needs to be treated in cases of Malassezia dermatitis? What are 2 options?
bacterial infections commonly associated with primary conditions (atopy)
- TOPICAL - BPO
- SYSTEMIC - anti-staphylococcal (Cephalexin, Cefpodoxime/Simplecef)
What 6 active ingredients are beneficial topical therapies recommended for cases of Malassezia dermatitis?
- selenium
- disulfide
- chlorhexidine
- miconazole, clotrimazole, enilconazole, ketoconazole
- nystatin
- lime sulfur
What 4 things alter frequency of topical therapy needed for cases of Malassezia dermatitis?
- severity of disease
- location of infection
- owner compliance
- other therapy - systemic
What are 2 options for degreasing shampoos in treating Malassezia dermatitis?
- selenium sulfide
- benzoyl peroxide - good for staph
can strip lipid layer chronically
