An elastofibroma is a noncancerous growth made of dense fibrous tissue and thick, abnormal elastic fibers. Elastic fibers are the springy fibers that let tissues stretch and return to shape.
Almost all elastofibromas develop in one particular place, between the lower tip of the shoulder blade and the ribs, tucked beneath the muscles of the upper back. A growth in this location is often called an elastofibroma dorsi.
An elastofibroma does not spread to other parts of the body and does not turn into cancer. Many need no treatment at all.
This article explains how doctors diagnose an elastofibroma and what your pathology report findings mean.
Elastofibromas are found mostly in adults over 55 and are more common in women. Imaging studies suggest that about 2 in 100 people over 60 have one, and many of them have no symptoms and never know.
Both sides are affected in a substantial number of people, although not always at the same time. A growth may be found on one side, with the other side discovered later, or noticed on a scan done for the first.
Many elastofibromas cause no symptoms and are found during imaging done for another reason. When symptoms do occur, they usually involve the shoulder blade:
Symptoms do not match the size of the growth. A large elastofibroma can be painless, and a smaller one can be uncomfortable.
The cause is not fully understood. The leading explanation is repeated friction between the shoulder blade and the ribs beneath it. This would explain why these growths appear in one specific location, and why they are more common in people who do heavy manual work. Many people with an elastofibroma have never done such work, so friction alone does not explain every case.
Most elastofibromas occur on their own. Families with more than one affected member have been reported, and some growths show an X-chromosome change. Neither finding is used in diagnosis, and no genetic testing is recommended for this condition.
An elastofibroma has a characteristic appearance on MRI, with strands of fat running through tissue that otherwise resembles muscle. When the location and the imaging findings are typical, the diagnosis can often be made without removing tissue.
A pathology report is produced when a sample is taken in a biopsy or when the growth is removed. Under the microscope, an elastofibroma is made of dense collagen, the fibrous protein that gives tissue its strength, mixed with fat and with thick, irregular elastic fibers. The elastic fibers may form clumps or beaded, rope-like strands, and they give the growth its name.
These fibers can be hard to see on a routine slide, so pathologists often use a special stain to turn them black and make them easier to identify. The growth has no capsule and blends into the surrounding tissue. The cells are few in number and look normal, with no dividing cells and no dead tissue.
Your report may call an elastofibroma a tumor, a growth, or a pseudotumor, which means something that forms a mass without being a true tumor.
Experts continue to debate whether an elastofibroma is a true tumor or a reaction to long-standing friction. This debate does not change what it means for you. Under every view, an elastofibroma is noncancerous, does not spread, and does not become cancer.
A margin is the edge of tissue cut by the surgeon. Because an elastofibroma has no capsule and blends into the surrounding tissue, your report may say that it extends to a margin.
For an elastofibroma, a positive margin does not mean what it does for cancer. Surgeons remove the growth with only a small rim of normal tissue, since taking more would not help. Even so, these growths rarely come back.
The outlook is excellent. An elastofibroma is noncancerous, does not spread, and does not become cancer. After removal, it rarely comes back, and long-term follow-up studies report people remaining free of the growth for years afterward.
When an elastofibroma is left in place, it grows very slowly. Many people live with one indefinitely without it causing trouble.