Week 3 Pathology + Embryology

Question 1

Keloids of external ear

- What are they and what are they made of.

Answer 1

• Excessive hypertrophic scar formation

- Immature Type III collagen, particularly common on earlobes after trauma or piercings of ears.

Question 2

Malignant otitis externa

- Main agent, risk factors

Answer 2

• pseudomonas aeruginosa

- diabetics and patients with leukemia

Question 3

Aural polyps

- What are they and what are they composed of?

Answer 3

• benign inflammatory lesions that arise from within the external auditory canal.
• ulcerated and inflamed granulation tissue = friable and bleeds easily

Question 4

Acute Otitis Media

- main agent, hx, complication

Answer 4

• strep pneumoniae
• hx of URI that extends from the naso pharynx
• Acute mastoiditis
• bulging puss with fluid into the external auditory meatus

Question 5

Chronic Otitis Media

- hx, eardrum characteristics, sx, complication

Answer 5

• recurrent ear disease in early childhood
• ear drum = retracted, scarred, perforated
• SX: Otorrhea and painless discharge
• Complication: Cholesteatomas

Question 6

Cholesteatoma

- What is it, complications

Answer 6

• mass of accumulated keratin and squamous mucosa = external ear canal through perforated ear drum into middle ear.

Question 7

Osteosclerosis

- what is it, special stat, most frequent site.

Answer 7

• Formation of new spongy bone around the stapes and oval window
• most common conductive hearing loss in young and middle aged adults in the US. Female > Male (2:1)
• most frequent site: immediately anterior to the oval window, causing bony ankyloses

Question 8

Meniere Disease

• what is it
• triad sx
• what is it also called, what is pathogenesis

Answer 8

• Idiopathic disorder of the inner ear aka endolymphatic hydrops: Dilation of cochlear duct and saccule, dilates entire endolymphatic system, causes rupture, etc.
• Triad SX: Tinnitus, vertigo, hearing loss.
• Note: postnatally, Mumps is the most common cause of deafness, unilateral.

Question 9

Embryology: Auricle + Malleus + Incus + Stapes

Answer 9

• Auricle = 1st and 2nd arch
• Malleus + Incus = 1st arch
• Stapes = 2nd arch

Question 10

Embryology: External Auditory Canal

Answer 10

• 1st cleft

Question 11

Embryology: Tympanic Cavity

Answer 11

• 1st pouch

Question 12

Embryology of Membranous labyrinth

Answer 12

• Surface ectoderm => Otic Placodes => Otic/Auditory Vesicles => Membranous labyrinth.

Question 13

Embryology of the ear in general

Answer 13

Rhombencephalon.

Question 14

Embryology of Eyes (Day 22)

Answer 14

Optic Groove => Optic Vesicles => Lens placode => Optic cup + stalk.

PAX6 = master gene in eye development
PAX2 = expressed in stalk.