Ear Anatomy and Cytology
Clinical Pathology
Normal anatomy
• The ear canal is a cartilaginous structure lined
with skin (epithelium).
• Hair follicles, sebaceous glands, and apocrine
glands line the entire canal to the eardrum.
• In the normal ear, glandular secretions and
epithelial cell migration, move dirt and debris
away from the ear drum.
• A normal ear exam should reveal a smooth, noninflamed epithelial lining and an intact tympanic
membrane.
Anatomy continued…..
• The tympanic membrane is a thin, semitransparent membrane that separates the
external canal from the tympanic cavity.
• Transmits sounds to the hearing apparatus.
Otitis
• Definition: Inflammation of the ear canal
and/or pinnae.
Otitis externa
• Inflammation of the ear canal to the tympanic
membrane.
Otitis Media
• Inflammation of the tympanum and the
tympanic bullae.
Otitis Interna
• Inflammation of the hearing apparatus.
• Neurologic signs and deafness are usually
present.
Causes of ear disease
•
•
•
•
•
•
Abnormal conformation
Ectoparasites
Systemic diseases, allergies, endocrine disease.
Tumors
Foreign bodies
Trauma
Diagnosis of ear problems
• Clinical signs:
▫ Inflamed ear canal
▫ Color of discharge
▫ Neurological signs
• Otoscopic exam
• Ear swab cytology
• Culture/sensitivity
Ear Cytology Technique
• Using a cotton tip
applicator, gently swab
ear canal.
• Gently roll the swab
along a clean glass slide.
• Heat fix
• Stain
▫ Diff-quick
▫ Gram stain
Cytological exam
• Bacteria
▫ Rods or cocci
 Pseudomonas, Proteus, Staphlococcus, Streptococcus
• Yeast
▫ Malassezia pacydermatitis
• WBC’s
▫ neutrophils
• Epithelial cells
• Neoplastic cells
• Earmites
Bacterial Otitis
• May see large numbers of bacteria, often
phagocytized bacteria in neutrophils.
• May see large numbers of neutrophils.
• May have mixed infections (rods and cocci)
• Discharge color
▫ Creamy, dark, yellow-light brown usually is
Staph/Strep
▫ Thick, odorous, pale yellow discharge usually is
Pseufomonas, Proteus
• Do culture/sensitivity especially if rods are found
Malassezia Otitis
•
•
•
•
Yeast are normal inhabitants
>10 yeast/HPF is abnormal.
Discharge: dark brownish exudate, yeasty odor.
May be present with bacteria (mixed infection).
Treatment of Otitis
• Depends on organism causing problems.
• Topicals
▫ Antifungals
▫ antibacterials
• Systemic drugs
▫ Antibiotics
▫ Antifungals
• Treat underlying disease