Congenital Orbital Anomalies

Question 1

What is anophthalmia, and what are the 3 types?

Answer 1

Total absence of tissues of the eye

1. Primary: rare, usually bilateral; failure of primary optic vesicle to grow out from cerebral vesicle
2. Secondary: rare, lethal; 2/2 gross abnormalities of neural tube
3. Consecutive: secondary degeneration of optic vesicle

Question 2

Definition of microphthalmia?

Answer 2

small eye with axial length at least 2 SD below the mean for patient’s age

Question 3

Most common location of orbit-involving meningocele, encephalocele, or meningoencephalocele?

Answer 3

Near medial canthus (may displace globe inferolaterally) or over bridge of nose

Question 4

Definition and examples of hamartomas?

Answer 4

anomalous growth of tissue consisting of mature cells normally found at involved site (capillary hemangiomas, neurofibromas)

Question 5

Definition and examples of choristomas?

Answer 5

tissue anomalies consisting of cell types NOT normally found at the involved site (dermoid cyst, epidermoid cyst, dermolipoma, teratoma)

Question 6

Difference between dermoid and epidermoid cysts?

Answer 6

• Dermoid cysts are lined by keratinized epithelium, contain dermal appendages (hair follicles, sebaceous glands), and are filled with both oil and keratin.
• Epidermoid cysts are lined by epidermis only, do NOT contain dermal appendages, and are filled with keratin only.

Question 7

Most common location of orbital dermoid cyst?

Answer 7

lateral brow adjacent to frontozygomatic suture

Question 8

Clinical presentation of dermoid cyst?

Answer 8

palpable, smooth, painless, oval mass present at birth that slowly enlarges.

Question 9

What is a dumbbell dermoid cyst?

Answer 9

dermoid cyst in temporal fossa expanding through the frontozygomatic suture into the orbit.

Question 10

Pulsatile proptosis with mastication?

Answer 10

dumbbell dermoid cyst

Question 11

CT appearance of dermoid cyst?

Answer 11

well-defined cyst with enhancing wall and non-enhancing lumen, often with partially calcified margin or rim

Question 12

Treatment of dermolipoma?

Answer 12

Surgery if large, symptomatic (fine overlying hairs can be irritating), or cosmetically unacceptable. These can be deep, but only the anterior, visible portion should be excised with efforts to spare the overlying conjunctiva

Question 13

Differential for dermatolipoma?

Answer 13

prolapsed orbital fat, prolapsed palpebral lobe of lacrimal gland, lymphoma

Question 14

Histology of teratoma?

Answer 14

composed of all three germ layers (ectoderm, mesoderm, endoderm), usually cystic, complex arrangement of various tissues, lined by any type of epithelium (respiratory, GI, etc), can contain islands of various tissue types (cerebral, hyaline cartilage, etc.)

Question 15

Clinical presentation of teratoma?

Answer 15

profound unilateral proptosis at birth

Question 16

microphthalmia with orbital cyst: cause, and laterality

Answer 16

failure of choroidal fissure to close in the embryo; usually unilateral