Cytologic evaluation of otic exudates

The multifactorial nature of otitis externa requires accurate etiologic information to ensure therapeutic success. The collection and preparation of cytologic samples of otic exudates are simple to perform, and information of immediate diagnostic and therapeutic value can be attained. Evidence of epidermal hyperplasia and increased glandular secretory activity suggests a noninfectious cause. Large numbers of microorganisms and infiltrating leukocytes confirm the presence of infection. The presence of ear mites, particularly O. cynotis, is always significant. Abnormal epithelial cells that appear singly or in sheets and clusters support the diagnosis of neoplasia; the extent of cell differentiation determines malignancy. Inflammatory cells and acantholytic keratinocytes from vesicular otic lesions suggest autoimmune skin disease.