H&N

Question 1

Benign mimicker of NPC?

Answer 1

Retained secretion, Lymphood hyperplasia, Retropharyngeal lymph nodes, Mucosal inflammatory changes

Question 2

When to consider CT for NPC?

Answer 2

Cortical invasion(sinuses and petrous temporal bone), tumor calcification

Question 3

What skull base structures to look for NPC invasion?

Answer 3

6 bones: clivus, both pterygoid bones, both petrous apices, sphenoid sinus walls
3 foramina: rotundum, ovale, lacerum
3 canals: vidian, pterygopalatine, hypoglossal
3 fissures/fossa: pterygopalatine fossa, pterygomaxillary fissure, orbital fissure

Question 4

Where can NPC invades througb PPF(pterygopalatine fossa)?

Answer 4

• inferior orbital fissure to orbit
• vidian canal to foramen lacerum(skull base and ICA)
• foramen Rotundum to middle cranial fossa
• sphenopalatine foramen to nasal cavity
• pterygopalatine canal to oropharynx
• pterygomaxillary fissure to infratemporal fossa

Question 5

Chordoma arises from__?

Answer 5

Notocord

Question 6

Key imaging features of chordoma?

Answer 6

• midline arising from clivus
• chunks of destroyed bone within the tumor
• some may have cystic areas
• relatively avascular but variable contrast enhancement

Question 7

Ddx of chondroma?

Answer 7

Ecchordosis physaliphora is a congenital benign hamartomatous lesion derived from notochord remnants, usually located in the retroclival prepontine region, but can be found anywhere from the skull base to the sacrum.

Question 8

Site of chondrosarcoma?

Answer 8

Off-midline, arises at synchondrosis between petrous temporal bone and clivus

Question 9

Total radiation dose and predisposing factor for radiation induced sarcoma?

Answer 9

• Total radiation dose > 55Gy

- Patient with NPC at risk

Question 10

Sites of radiation induced sarcomas?

Answer 10

Any site within radiation field but usually deep seated in skull base

Question 11

Subtypes of radiation induced sarcomas?

Answer 11

Osteosarcoma, Fibrosarcoma, Angiosarcoma, Spindle cell sarcoma

Question 12

Biological behaviour of acoustic neuroma?

Answer 12

Tend to expand the bone but not destroy the bone

Question 13

Origin of sinonasal ca?

Answer 13

Epithelial(SCC, adenoCA, anaplasticCA) or Salivary(adenocystic, acinic cell, mucoeoidermoid)

Question 14

Site of olfactory neuroblastoma?

Answer 14

Unilateral superior nasal cavity(spread into sinuses and through cribriform plate into cranium)

Question 15

Site of juvenile angiofibroma?

Answer 15

Arises at junction of the lateral wall and roof of the posterior superior nasal cavity adjacent to sphenopalatine foramen

Question 16

Vascular supply of juvenile angiofibroma?

Answer 16

ECA usually internal maxillary or ascending pharyngeal, occasional ICA