Bone & Soft Tissue

Question 1

What is the most common primary bone tumor in children?

Answer 1

Osteosarcoma

Question 2

Which 3 pediatric tumors share t(11;22) translocation?

Answer 2

Ewings, PNET and Desmoplastic Small Round Cell Tumor (but has a different breakpoint than Ewing’s and PNET)

Question 3

This tumor from the finger of a young child has a VERY characteristic appearance of these spindle cells with eosinophilic hyaline globules. What is the tumor?

Answer 3

Infantile fibromatosis

Question 4

What is the MOST IMPORTANT factor in prognosis of neuroblastoma that trumps everything else?

Answer 4

Age of the patient (THE most impt)

<1yr do ok

>5 poor

Good prognosis: hyperdiplioid, no structual chr abnormalities and expression of TrkA neurotrophin receptor

Question 5

What pediatric soft tissue tumor has characteristic dot like staining with desmin?

Answer 5

Desmoplastic small round blue cell tumor

Question 6

What are some poor prognostic factors in neuroblastoma?

Answer 6

MYC-N amplification (>10 copies/cell)

ALK amplification

Chromosome 1p36.3 or 11q23 deletion and gain of 17q

*although not formally used in risk stratification, chr 11q loss, unlike 1p loss, is seen in ABSENCE of NMYC amplification and may be independent marker of prognosis in NMYC non amplified diploid cases

Near-diploid DNA content (patients <18 months with metastatic disease)

Increasing age

*tend to express TrkB neurotrophin and BDNF

Question 7

What is the most common solid tumor in childhood?

Answer 7

Rhabdomyosarcoma

*less than 1 year old is neuroblastoma

Question 8

What % of children with osteosarcoma have metastatic disease at presentation

Answer 8

15%

Question 9

What primary 2 genes are altered in osteosarcomas?

Answer 9

TP53 and RB1

Question 10

What 5 syndromes are associated with increased risk of osteosarcoma

Answer 10

Hereditary retinoblastoma

Li-Fraumeni

Rothmund-Thomson

Bloom

Werner

Question 11

What is the most common bone tumor s/p tx primary malignancy

Answer 11

50-80% osteosarcomas

Esp if radiation dose >1000 cGy

Average dose 4500-5400 cGy

Question 12

What are risk factors for osteosarcoma?

Answer 12

Black/African

Radium

Ionizing radiation

RB1

Question 13

What is the most common cause of non-diagnostic biopsy in osteosarcoma, and what is the most common type to result in non-diagnostic biopsies?

Answer 13

Sclerosis

Telangectatic

Question 14

What test can help differentiate chondrosarcoma from osteosarcoma?

Answer 14

IDH1 and IDH2 mutations are present in 61% of chondrosarcomas

Question 15

What are the 3 most important prognostic factors in osteosarcoma?

Answer 15

Complete resection

Local recurrence

Metastases

Question 16

What is the mechanism of secondary high dose methotrexate resistance in osteosarcoma?

Answer 16

dihydrofolate overexpression