Abstract
BackgroundRarely, Malassezia otitis presents as a painful, erosive otitis with an otic discharge containing Malassezia and neutrophils on cytology. There are no published reports of this type of suppurative Malassezia otitis (SMO). The role of Malassezia hypersensitivity in otitis is still unknown, and no association has been demonstrated with SMO. We compared Malassezia IgE levels, intradermal test and histology changes in SMO dogs with the more conventional Malassezia otitis (MO) presentation.ResultsThree dogs (case 1, case 2 and case 3) were diagnosed with SMO, one dog (case 4) was diagnosed with unilateral MO and unilateral SMO, and one dog (case 5) was diagnosed with MO. Only one case (case 4) with SMO/MO had a positive Intradermal Allergy Test (IDAT) and elevated IgE levels for Malassezia. Histopathology findings from SMO revealed: interface dermatitis (case 1 and 3), lymphocytic dermatitis (case 2) and chronic hyperplastic eosinophilic and lymphoplasmacytic dermatitis (case 4). Histopathology findings from MO showed perivascular dermatitis (case 4 and 5). All the cases were treated successfully.ConclusionsSMO presents with a distinct clinical phenotype in comparison with conventional MO. No consistent aetiology could be isolated. In these clinical cases it is possible that previous treatments could have influenced the results. More research is needed to understand the possible aetiologies and the pathogenesis of SMO.
Highlights
Malassezia otitis presents as a painful, erosive otitis with an otic discharge containing Malassezia and neutrophils on cytology
Malassezia pachydermatis is commonly involved in canine otitis externa [1, 2]
The authors have recognised another type of chronic Malassezia otitis that presents with pain, a suppurative exudate, and sometimes with ulceration of the ear canal
Summary
Malassezia otitis presents as a painful, erosive otitis with an otic discharge containing Malassezia and neutrophils on cytology. There are no published reports of this type of suppurative Malassezia otitis (SMO). We compared Malassezia IgE levels, intradermal test and histology changes in SMO dogs with the more conventional Malassezia otitis (MO) presentation. Clinically healthy dogs have not been shown to elicit an immediate hypersensitivity response to intradermal injection of M. pachydermatis extracts, in contrast, dogs with Malassezia otitis do [4]. This supports the possibility that a type I hypersensitivity. The authors have recognised another type of chronic Malassezia otitis that presents with pain, a suppurative exudate, and sometimes with ulceration of the ear canal. Cytology is the only test to differentiate between the more conventional Malassezia otitis (MO) and suppurative Malassezia otitis (SMO), in which yeast
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