Myelolipoma

by Jason Wasserman MD PhD FRCPC
July 11, 2022


What is a myelolipoma?

Myelolipoma is a non-cancerous tumour that is typically found in the adrenal gland. It is the second most common type of adrenal gland tumour.

What are the symptoms of a myelolipoma?

Most myelolipomas do not cause any symptoms and are discovered incidentally when abdominal imaging is performed for another reason. However, some tumours can cause symptoms such as abdominal pain or distension or and large tumours may cause symptoms associated with compression of nearby organs.

What causes a myelolipoma?

There is no known cause for most patients who develop myelolipoma.

Is myelolipoma a type of cancer?

No. Myelolipoma is a benign (non-cancerous) tumour.

How is the diagnosis of myelolipoma made?

The diagnosis of myelolipoma can be made after a small sample of tissue is removed in a procedure called a biopsy or after the entire tumour is removed. The tissue is then sent to a pathologist for examination under the microscope.

What does a myelolipoma look like under the microscope?

When examined under the microscope, myelolipoma is made up of two types of cells: adipocytes (fat cells) and cells normally found in the bone marrow. The relative proportion of these two types of cells varies between tumours.  Pathologists use the term mature adipocytes to describe the normal-appearing fat cells typically found throughout the tumour. The bone marrow cells normally found in this tumour include megakaryocytes and immature white blood cells. Pathologists use the term trilineage hematopoiesis to describe this combination of normal bone marrow elements. A rim of the normal adrenal gland may be seen surrounding or adjacent to the tumour.

Because large tumours may bleed, your pathology report may describe the presence of hemorrhage, red blood cells, or hemosiderin within the tumour. Large open spaces called cysts may also be seen, especially in large tumours.

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