Osteoblastic and Osteolytic Metastasis

Posted: January 12, 2014 in Repeated Topics In PG Entrance
Tags: , , , ,

I am writing this article because its a direct question frequently asked in PG examinations.

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What are the so called “osteoblastic meatstasis” and “osteolytic metastasis”?

  • Normal bone development and maintenance are sustained through a balanced communication between osteoclasts and osteoblasts.
  • Invasion of the bone compartment by cancer cells causes an imbalance in their activities and results in predominantly bone lysing or bone forming phenotypes depending on the origin of the cancer.
  • Tumor-induced bone lesions usually exhibit disturbances of both cell types.
  • Thus, osteolytic activity is activated in a predominantly osteoblastic lesion and vice versa.
  • The recent development of agents that target the osteolytic components of bone metastasis, including bisphosphonates and denosumab, showed promising results in osteolytic bone diseases such as multiple myeloma but were less effective in improving the osteoblastic bone disease found in prostate cancer.
  • Thus, while osteolytic components are present in both osteoblastic and osteolytic bone lesions, inhibition of the osteolytic component alone is not sufficient to alter the vicious cycle leading to tumors with an osteoblastic phenotype.

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Causes of Osteolytic and Osteoblastic metastases

*Causes of Osteolytic metastasis:
[Mnemonic: KT(LGB) : *LGB: Lateral Geniculate Body.]
– Kidney (expansile) and Thyroid : Expansile lytic osseous metastasis are characteristic of Renal cell carcinoma (kidney) and Thyroid cancers.
– Lung.
– Gastrointestinal tract (GIT).
– Breast (occasionally).
– Less commonly melanomacarcinoma of bronchus and pheochromocytoma may also present with expansile lytic lesions.

*Causes of Osteoblastic metastasis:

[Mnemonic: PSCO-BU: *PSCO: Posterior sub-capsular opacification]
 Prostate.
– Seminoma.
– Carcinoid. 
– Ovary.
– Breast (may be mixed).
– Uterus.
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