Chondrosarcoma of skull base/Sphenoid bone in the eye of a Radiologist

1. Chondrosarcoma
of skull Base
Dr.Santosh Atreya
Phase-B Resident
Department of Radiology & Imaging
BSMMU,Dhaka

2. Introduction
• Chondrosarcoma of the skull base are rare
tumors.
• The incidence is reported to be 0.03 per
100,000 persons in the United States

3. Epidemiology
• Chondrosarcomas of the base of the
skull make up only a small fraction of
all chondrosarcomas
• Head and neck chondrosarcomas- only 7%.

4. • Petro-occipital synchondrosis (most common)
• Sphenoethmoidal junction
• Sella turcica
• The majority of chondrosarcomas of the base of the
skull are located off the midline
• Chordomas-usually midline.
Location

6. • The petro-occipital synchondrosis, also known
as the petroclival synchondrosis, is a primary
cartilaginous joint between the basilar part of
the occipital bone and the petrous temporal
bone.
• 'Fissure' and 'junction' are other terms used to
describe this structure,
however, synchondrosis is technically more
correct.

7. Risk factors
• The vast majority –sporadic
• However, some predisposing conditions are
reported, and include:
• previous trauma/fractures

8. Clinical presentation
• Patients usually present due to mass effect,
either on adjacent brain, brainstem, cranial
nerves or (if extension inferiorly) structures of
the superior neck.

9. Chondrosarcoma
• Skull:Painless expanding mass
Types:
• Myxoid (Low grade)-Most common
• Dedifferentiated
• mesenchymal

10. Radiographic features
• Plain radiograph
• Only of historical interest,
• Lytic lesions in 50% and
calcifications in
approximately 60%.
• Differentiation of
chondrosarcomas from
other skull base tumors
was very difficult prior to
cross-sectional imaging.

11. CT
• Thin triplanar bone
algorithm images is
important is confirming
bony involvement and
demonstrating
calcification of the tumor,
often in
characteristic rings and
arcs (70%)
• Centered off mid-line
• Petro-occipital fissure

12. MRI
• T1: low signal
• T2: high signal
• T1 C+ (Gd)
– usually heterogeneous
enhancement
– Scalloped well
circumscribed margin.

13. Chondrosarcoma of the sphenoid in a 56-year-old man. (A) Axial, T2-weighted
MR image shows a lobulated mass at the sphenoid . The mass contains abundant
intermediate signals but also includes hyperintense foci. (B) Axial, contrast-
enhanced, MR image with fat suppression shows peripheral enhancement that
indicates chondrogenic tumor. A pathological analysis revealed grade 1
chondrosarcoma.

14. Differential Diagnosis
• Chordoma
– usually midline projecting posteriorly
• Meningioma
– usually not high T2 signal
– calcification pattern usually not chondroid
• Metastases
– calcification not as common
– more destructive
• Nasopharyngeal carcinoma
– calcification uncommon
– epicentre in the nasopharynx
• Pituitary macroadenoma
– calcification uncommon
– centred on pituitary fossa
• Cavernous sinus hemangioma
– also high T2 signal but usually homogeneous
– no calcification

15. Chordoma
Found in mid-line
Most common-
Sacrococcygeal
30-50%

16. Treatment
• Multidisciplinary approach should be
implemented in managing this rare tumour
apart from radical resection as its mainstay
treatment.

17. Take Away Messages for Radiology
Resident
• Skull base chondrosarcoma typically forms an
expansile mass with multilobulated margins. CT
shows an osteolytic mass. Typical ring and arc
calcification can be seen
• The tumor demonstrates iso- to hypointensity on
non-contrast T1-weighted and hyperintensity on
T2-weighted MR images.
• The contrast enhancement pattern is
heterogeneous with a predominance at the
periphery.