Ch48 Tumours of the skull

Question 1

What features of a bone lesion suggest malignancy?

Answer 1

Irregular margins, no sclerosis and multiple lesions

Question 2

What is the most common primary bone tumour of the skull?

Answer 2

Osteoma - round sclerotic tumours arising from the outer table of the skull. Hot on bone scans.

Question 3

What is Gardner’s syndrome?

Answer 3

Multiple osteomas, colon polyps and soft tissue tumours

Question 4

What are the two types of haemangioma?

Answer 4

Cavernous and capillary (very rare). Treat with excision or cement vertebroplasty if in the spine.

Question 5

What are the x-ray / CT appearance of a haemangioma?

Answer 5

Trabecular pattern. If radial then has a sunburst appearance. Sclerotic margins in 1/3,

Question 6

What are dermoid / epidermoid cysts?

Answer 6

Benign ectodermal inclusion cysts

Question 7

What is the difference between a teratoma and a dermoid?

Answer 7

Teratomas contain 2 or more germ cell layer tissue derivatives e.g. teeth, dermoids only contain ectoderm. Whilst Epidermiods contain squamous epithelium and keratin only.

Question 8

What is this midline lesion?

Answer 8

Skull dermoids

Question 9

What is this lesion?

Answer 9

Langerhans cell histiocytosis

Appears as a punched out lytic lesion skull xray

Question 10

Where do chodomas arise?

Answer 10

Clivus and sacrum

Question 11

What cells are characteristic of a chordoma?

Answer 11

Physaliphorous cells (contain intracellular mucin)

Question 12

What are chordomas remnants of?

Answer 12

Notochord (which normally forms the intervertebral discs)

Question 13

What is the recurrence rate of chordomas?

Answer 13

85% so aggressive radiotherapy or proton beam therapy is employed.

10% metastasise (lung, liver and bone)

Question 14

What are the MRI features of a chordoma?

Answer 14

Bright on T2, dark on T1 and no enhancement.

Question 15

What % of primary bone tumours are chordomas?

Answer 15

50%

M>F

Usually sacrococcygeal but can be in C2.

Limited by presacral fascia so do not normally invade the rectum.

Question 16

What is the treatment for sacrococcygeal chordoma?

Answer 16

En-bloc excision (Sacrectomy)

High dose radiotherapy / proton beam more effective

Question 17

What chemotherapy is used for chordomas?

Answer 17

Imatinib aka Glivex (tyrosine kinase inhibitor of the mTOR pathway). Stabilises the disease in 70% Ref: Hindi et al 2015

Question 18

What conditions cause diffuse thickening of the skull?

Answer 18

Hyperostosis frontalis interna

Fibrous dysplasia

Osteopetrosis

Paget’s disease

Question 19

Diagnosis?

Answer 19

Hyperostosis frontalis interna

Question 20

Diagnosis?

Answer 20

Fibrous dysplasia

Question 21

Diagnosis?

Answer 21

Paget’s disease

Question 22

Diagnosis?

Answer 22

Osteopetrosis

Question 23

What is the median survival of a chordoma?

Answer 23

6.3 years

Question 24

What is the classical feature of hyperostosis frontalis interna?

Answer 24

The midline bone at the insertion of the falx is spared.

More common in Females (9:1)

Associated with acromegaly, hyperprolactinaemia, hyperphosphataemia and DISH.

Question 25

How do you investigate someone with suspected hyperostosis frontalis interna?

Answer 25

GH / Prolactin / ALP / Ca / Parathyroid levels Skull Xray or CT

Question 26

How is hyperostosis frontalis interna treated?

Answer 26

If needs treating, then excision and cranioplasty

Question 27

What is fibrous dysplasia?

Answer 27

A non-neoplastic condition where bone is replaced with expansile fibrous connective tissue. Risk of malignant transformation \<1%.

Question 28

What sites are commonly affected by fibrous dysplasia?

Answer 28

Skull, face, proximal femur and ribs

Question 29

What is McCune-Albright syndrome?

Answer 29

Polyostosic fibrous dysplasia, precocious puberty and cafe au lait spots

Question 30

What is this X-ray finding?

Answer 30

Shepherd's crook deformity, associated with fibrous dysplasia of the prox femur

Question 31

What are the 3 patterns of involvement of fibrous dysplasia?

Answer 31

1. Mono-ostotic 2. Poly-ostotic 3. Part of McCune Albright syndrome (polyostotic fibrous dysplasia, precious puberty and cafe au lait spots)

Question 32

What are the 3 forms of fibrous dsyplasia?

Answer 32

Cystic, Sclerotic and mixed

Question 33

What are the reasons to treat fibrous dysplasia?

Answer 33

Cranial nerve-related compression (visual loss, diplopia, hearing loss, trigeminal neuralgia and facial weakness) Cosmesis Pathological fractures (long bones / maxilla etc)

Question 34

What imaging studies do you request for fibrous dysplasia?

Answer 34

Skeletal survey, CT head and dental films (OPG)

Question 35

What is the natural history of fibrous dysplasia?

Answer 35

Slow growth which does not usually progress after skeletal maturity is reached so if possible wait until age 10 /12 years before treatment. Rapid growth can occur with GH excess and this should be managed aggressively.

Question 36

What are the medical treatment options for fibrous dysplasia?

Answer 36

Calcitonin Bisphosphonates Treat GH excess