Primary Bone Tumors

2. Changes with Aging (important to remember for the DDx)

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      1. Most bone TMRs arise from distant METS during this period.

         1. Neuroblastoma

         2. Wilm’s TMR

         3. Rhabdomyosarcoma

   2. Age 5 to 20

-this is a time of increased bone turnover and therefore increasedd risk of TMR formation/growth.

-most benign and malignant bone (of all ages) TMRs occur here.

1. Most TMRs at this age are benign

   1. #1 excised TMR is Osteochondroma (b/c it sticks out from the side of the bone – very noticeable)\

-fig 28-26

1. Most sarcomas occur here b/c of the increase turnover of the bone

   1. #1 is Osteosarcoma (1000-2000/year)

   2. #2 is Ewing’s Sarcoma (~400/year in the U. S.)

2. Primary Bone TMR

   1. b/c of  turnover, this is when most of the primary bone malignancies occur.

1. Age 20-40

   1. Few malignant bone TMRs occur.

   2. Most common is GCT of Bone, Fibrosarcoma/Malignant Fibrous Histiocytoma, Lymphoma

   3. Can immediately r/o Ewing’s, Osteosarcoma, METS (usually)

2. Over 40 Years old - Assume any excessive bone growth is malignant until proven otherwise

   1. #1 TMR is some kind of METS

   2. #1 Primary marrow TMR = Myeloma

   3. #1 Sarcoma = Chondrosarcoma (almost exclusive to older adults)

3. Bone TMR Sites

   1. Bone forming

      1. Metaphysis

      2. Knee

      3. Proximal Humerus

   2. Bone marrow derived/other

      1. Diaphysis

      2. Pelvis

   3. Solitary Bone Lesions (DDx of Holes in bones)

      1. Neoplasm: benign or malignant.

      2. Osteomyelitis: more common and mimics nearly everything.

      3. Cysts: idiopathic or the cystic remnant of a TMR.

      4. Focal Dysplasias: can mimic neoplasms.

      5. Metabolic Diseases: such as Hyperparathyroidism; brown TMR – check blood and look at other bones (is the problem systemic like a metabolic disease would beincreased)

      6. Infarcts: that mineralize and look like cartilaginous lesions.

4. Naming Bone TMRs

   1. Generally

      1. “-oma” = benign

      2. “-sarcoma” = malignant

5. General Prognosis of Bone TMRs

   1. Most are benign and w/o incident. They are usually removed b/c:

      1. They get in the way of a ligament (the growth)

      2. They are deforming (ex. if they are on the face)

      3. Incidental finding on x-ray and the pt or physician is paranoid.

      4. They cause a pathological frax (most common presentation)

Category: Orthopedics Notes