Bone tumour made easy part 2

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.

  • Age
  • Part of bone
  • Type of bones involved

1. By Age

Capture

2. By part of bone

Capture1.

3. By location

3

Osteosarcoma

  • 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.

Ewing’s sarcoma

  • 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.

Chondrosarcoma

  • 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.

Fibrosarcoma

  • 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

Osteosarcoma

  • 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

Acute osteomyelitis

  • 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.

Reference: radiopaedia.org

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