Brief Answer:
Marrow fibrosis indicates and underlying condition- further details below

Detailed Answer:
Hello and welcome to "Ask a Doctor" service,

I carefully read your query and understand your concern.

Cancellous bone is also called the spongious bone, which is that area of some bones that has bone marrow and produces blood (the long bones, the vertebra and the hip bone have these generally).
Reactive marrow fibrosis is a change in the bone marrow where the normal cells that should be there (to produce blood) are substituted by fibrous tissue (similar to the scar tissue).

In itself, marrow fibrosis is not cancer but it may indicate the presence of another condition- this is why it is called reactive.

The underlying condition can be many from infection, storage disease, autoimmune conditions and in some cases, even malignancies (cancer).

The biopsy should give more information on the kind of fibers (reticulin or collagen) and if fibrosis is local or spread. These help further guide on the possible cause.
Reticulin fibers, for instance, are more often related to non-cancer conditions while collagen fibers are more common with cancer.

I hope this answers your query and is helpful to you. I remain at your disposal in case further medical assistance is needed.

I wish you well.

Regards,
Dr.Antoneta Zotaj, General and Family Physician

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