Elastic fibers are thin, stretchy strands in the body’s supporting tissue. They let tissues such as the skin, lungs, and large blood vessels stretch and then spring back to their original shape. Pathologists identify elastic fibers when they examine sun-damaged skin, blood vessels, and some tumors. A special stain that highlights elastic fibers also helps the pathologist decide whether a cancer has grown into a blood vessel or through the lining of the lung.
This article explains what elastic fibers are, where they occur in the body, and why they appear in pathology reports.
What are elastic fibers made of?
Elastic fibers consist mainly of a protein called elastin, wrapped around a thin framework of other proteins. Elastin can stretch well beyond its resting length and then recoil, much like a rubber band. Elastic fibers work together with collagen, which is strong but does not stretch. Collagen gives tissue its strength, while elastic fibers give it flexibility.
Where are elastic fibers in the body?
Elastic fibers are most plentiful in tissues that need to stretch and recoil many times a day. The main places include:
- Skin. The dermis, the layer beneath the skin’s surface, contains many elastic fibers that keep the skin firm and springy.
- Lungs. Elastic fibers let the lungs expand when you breathe in and recoil when you breathe out. A layer of elastic fibers also runs through the thin lining that covers the lungs, called the visceral pleura.
- Large blood vessels. Arteries contain sheets of elastic fibers, called elastic laminae, that help them stretch with each heartbeat.
- Some cartilage. The cartilage of the outer ear and the epiglottis contains elastic fibers, which makes it bendable.
How do pathologists see elastic fibers?
Pathologists see elastic fibers best with a special stain, often called an elastic stain, such as the Verhoeff-van Gieson stain. This stain colors elastic fibers black against a pink or red background. On a routine slide, elastic fibers are hard to tell apart from other fibers, so pathologists use the special stain when their exact position matters.
Why do elastic fibers matter in a pathology report?
Elastic fibers matter in a pathology report because changes in them, or their position next to a tumor, can affect a diagnosis or a cancer stage. Common situations include:
- Lung cancer staging. When a lung cancer grows through the elastic layer of the visceral pleura, pathologists call it visceral pleural invasion. Under the AJCC 8th edition staging system, this raises a tumor 3 cm or smaller to stage T2a. An elastic stain helps the pathologist see whether the tumor has crossed this layer.
- Vascular invasion. Elastic fibers outline the walls of veins and arteries. An elastic stain can show tumor cells inside a blood vessel that might otherwise be hard to see.
- Sun-damaged skin. Years of sun exposure cause elastic fibers in the skin to clump and break down. Pathologists call this solar elastosis.
- Blood vessel disease. Some types of vasculitis, or blood vessel inflammation, damage the elastic layers in artery walls.
- Tumors. An elastofibroma is a noncancerous growth made of many thick, abnormal elastic fibers. It usually forms under the shoulder blade.
Questions to ask your doctor
- Why did the pathologist order an elastic stain?
- Did the elastic stain show that the tumor grew into a blood vessel?
- If I have lung cancer, did the tumor invade the visceral pleura?
- How does this finding affect the stage of my cancer?
- Does my skin biopsy show sun damage, such as solar elastosis?
- Do I need any further tests or treatment because of this finding?
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