1. Regarding desmoplastic fibroma (Choose a single answer):
a) Desmoplastic fibroma is a malignant neoplasm.
b) The most common site of occurence is the ilium.
c) Curretage is the treatment of choice.
d) "Pseudo-trabeculae" are a classic feature of desmoplastic fibroma
2. Regarding Ewings sarcoma (Choose a single answer):
a) Ewings sarcoma is typically a tumor of middle-age and beyond.
b) Tubular bones are most commonly affected in Ewings sarcoma in patients under 20 years old, with flat bones most commonly affected in those older than 20.
c) In Ewings sarcoma, bone metastases are uncommon and unlike the primary tumor, are usually blastic when they do occur.
d) The vast majority of occurrences of Ewings sarcoma in the long bones are of the central diaphyseal type.
3. Regarding osteochondroma
a) An osteochondroma is a bony projection with a cartilaginous cap arising from a bone preformed in cartilage
b) Malignant degeneration of osteochondroma to chondrosarcoma occurs in up to 20% of patients with hereditary multiple exostoses.
c) The cortex and medullary cavity of the host bone are not continuous with the osteochondroma.
d) The most common sites for osteochondroma are the hands and feet.
e) Almost all pseudoanerysms complicating osteochondromas arise from the popliteal artery
f) Benign osteochondromas generally do not demonstrate continued growth after skeletal maturity
Answers:
1. d
Desmoplastic fibroma is a locally aggressive, benign neoplasm of bone. It can be considered the intraosseous counterpart of the soft tissue desmoid tumor. The most common site of occurence is the mandible. Broad local resection is the treatment of choice. The lesion is prone to recur with curretage. "Pseudo-trabeculae" are a classic feature of desmoplastic fibroma.
2. b
Ewings sarcoma is a tumor of young people, with the peak age of incidence being 15 years old. Tubular bones are most commonly affected in Ewings sarcoma in patients under 20 years old, with flat bones most commonly affected in those older than 20. This is thought to reflect the red marrow distribution of the two age groups. In Ewings sarcoma, bone metastases are common, and usually ARE a lytic destructive process similar in appearance to the primary tumor. The vast majority of occurrences of Ewings sarcoma in the long bones are of the central diaphyseal type.
3. a, b, e, f
An osteochondroma is a bony projection with a cartilaginous cap arising from a bone preformed in cartilage. Malignant degeneration of osteochondroma to chondrosarcoma occurs in up to 20% of patients with hereditary multiple exostoses. The cortex and medullary cavity of the host bone ARE continuous with the osteochondroma. The most common sites of involvement include the distal femur, the proximal tibia, and the humerus. Almost all pseudoanerysms complicating osteochondromas arise from the popliteal artery. Benign osteochondromas generally do not demonstrate continued growth after skeletal maturity. In the presence of a large soft tissue mass or enlargement of a previously stable lesion chondrosarcomatous transformation must be considered.
