This is part 2 of a hopefully 3 parts series.
Approach to bone tumour in a more detailed way: trying to know which bone tumour it is.
- Part of bone
- Type of bones involved
1. By Age
2. By part of bone
3. By location
- Primary osteosarcoma: typically occurs in young patients (10-20 years) when the growth centers of the bone are more active during the puberty to adolescence time period.
- Secondary osteosarcoma: occurs in the elderly, usually secondary to malignant degeneration of Paget disease, extensive bone infarcts ,post-radiotherapy for other conditions, osteochondroma, and osteoblastoma.
Cloud like bone matrix with aggressive periosteal reaction in distal femur.
- Tumour of bone marrow
- Most characteristic is the moth eaten, permeative type of bone destruction
- Compared to osteosarcoma which occurs in metaphysis, Ewing’s normally is located in diaphysis.
Ewing’s sarcoma with cortical destruction
**Osteomyelitis can present and look like tumour, therefore whenever doing biopsy always send for microbiological culture and surgical pathology !
Dont touch lesion: cortical desmoid
- Athletic teenager
- Repetitive stress at the attachment of the adductor magnus aponeurosis at the posterior medial aspect of the distal femoral metaphysis.
- A little periosteal reaction
- Saucer-shaped radiolucent cortical irregularity involving the posteromedial aspect of the distal femoral metaphysis
Lymphoma of bone
- Commonly from secondary spread
- Primary bone lymphoma is less common.
- Commonly diaphysis with soft tissue extension.
- Normally in long bones, pelvis and ribs
- Can be primary or secondary (arising from echondroma or osteochondroma)
- By the time of diagnosis, normally is a big mass.
– Rings and arcs calcification
– Endosteal scalloping >2/3 of cortical thickness
– Moth eaten/permeative pattern
- Has poor blood supply so
– Does not enhance on gadolinium
– Does not respond to chemo. need complete resection.
- Primary or secondary after radiation or from chronic osteomyelitis or Paget’s disease
- Distinct but also similar to malignant fibrous histiocytoma (MFH)
- MRI: isointense to muscle in T1, hyperintense in T2
MFH of thigh
- other than conventional one, we have telangiectatic and surface OS
- Telangiectatic OS:
– Very vascular and presents almost exclusively as lytic lesion
– Most of the tumour comprises of large blood filled spaces separated by thin bony septations.
- Surface OS
– Good prognosis if marrow is not involved (resect for cure). If marrow is involved, it is treated as conventional OS.
– Parosteal (from inner layer of periosteum) and periosteal (from outer layer of periosteum)
– Periosteal is higher grade than parosteal but lower grade than conventional OS
– Parosteal OS imaging features: exophytic mass arising from the cortex with string sign (30% seen in CT/X ray, a radiolucent line separating the tumour and cortex of the bone), no aggressive periosteal reaction because they arise from the outer layer of periosteum, commonly in posterior femoral condyle
– Periosteal OS has aggressive periosteal reactions, contains chondroid matrix therefore is hyperintense in T2
** Differing from conventional OS with osseous matrix
- In general, osteomyelitis must extend at least 1 cm and compromise 30 to 50% of bone mineral content to produce noticeable changes in plain radiographs. Therefore, normally the changes are only recognizable 1 week after in children and up to 2 weeks in adults.
- Radiologic features are non specific:
– Regional osteopenia
– Focal osteolysis
– Aggressive periosteal reactions
– Endosteal scalloping
Diabetic osteomyelitis due to diabetic foot ulcer
In part 3 we’ll be discussing more on non aggressive lytic and blastic lesions.