Malassezia Dermatitis

• Caused by Malassezia pachydermatis
• Yeast, normally present in external ear canal and skin
• Clinical disease may cause yeast to proliferate and cause infection
• Grossly:
  • Regional lesions: muzzle, ears, interdigital, perianal
  • Or generalised disease
  • Erythematous, hyperpigmented, lichenified and scaly lesions with alopecia
• Microscopically:
  • hyperkeratosis, parakeratosis
  • Spongiotic pustular dermatitis
  • Acanthosis
  • Organisms are usually present, minimum 3-5 yeasts per high-power field must be found to imply cause of disease

Grossly, regional lesions may be seen around the muzzle, ears, interdigital, and perianal. Other common signs include erythema, hyperpigmentation, lichenified and scaly lesions with alopecia.

Microscopically, one may see;hyperkeratosis, parakeratosis, spongiotic pustular dermatitis, Acanthosis.