“Subepithelial lesion” on an endoscopy report means that, while the inner surface of the stomach or digestive tract looks normal, a structure lying beneath the lining is producing an outward bulge.
These used often to be called “submucosal tumours”. Today the term subepithelial lesion (SEL) is preferred, because the structure can arise not only from the submucosa but from different layers of the wall of the digestive tract.
Seeing a subepithelial lesion does not mean there is cancer. A large proportion of these lesions are harmless. But further investigation is sometimes needed to understand what the lesion is.
What causes it?
Different structures can lie behind a subepithelial appearance:
- Lipoma: arises from fatty tissue and is generally harmless.
- Leiomyoma: develops from smooth muscle; mostly harmless.
- GIST (gastrointestinal stromal tumour): can be of very low risk, but can also carry malignant potential.
- Ectopic pancreas: normal pancreatic tissue in a different location.
- Granular cell tumour
- Neuroendocrine tumour
- Cysts and structures arising from blood vessels
Sometimes the spleen, liver, gallbladder or another structure outside the wall of the digestive tract can press from outside and mimic the appearance of a subepithelial lesion.
Does endoscopy show what the lesion is?
Not always.
Standard endoscopy shows mainly the surface of the lining. Because a subepithelial lesion lies beneath the lining, it may not be possible to determine its exact type by looking at the surface alone.
The endoscopist assesses the lesion’s size, its location, whether its surface is smooth, whether there is an ulcer over it, and features such as its firmness and mobility.
But the really important question is: “Which layer of the wall of the digestive tract does this structure arise from?”
Why does EUS matter?
Endoscopic ultrasound (EUS) is one of the most useful methods for assessing subepithelial lesions. EUS allows:
- Which layer of the wall it arises from To be determined.
- Its true size To be measured.
- Its internal structure and borders To be assessed.
- Its relationship with blood vessels To be seen.
- Whether tissue sampling is appropriate To be assessed where needed.
Lipoma, GIST and leiomyoma can look similar at standard endoscopy, for instance, while EUS can narrow the differential diagnosis considerably.
Is a biopsy needed?
A biopsy does not have to be taken from every subepithelial lesion.
What is more, because a standard endoscopic biopsy samples only the surface lining, it may not give a diagnosis in a subepithelial lesion.
Where a tissue sample is needed, EUS-guided needle biopsy or other sampling methods may be used depending on the lesion’s features.
A biopsy being requested does not mean there is cancer.
What does finding a GIST mean?
GIST is a particular group of tumours that develop from the wall of the digestive tract, and is seen most often in the stomach.
Not every GIST is cancer.
How a GIST behaves varies with factors such as its size, its location, its cellular features and its mitotic count. So where GIST is suspected, the lesion needs assessing in detail.
Does the size of the lesion matter?
Yes, but it is not enough on its own.
In general, as size increases the assessment becomes more important. In lesions of about 2 cm and above in particular, or in structures with suspicious features on EUS, tissue diagnosis, removal or closer follow-up may come into consideration.
But the decision is not made from centimetres alone.
Should every subepithelial lesion be removed?
No.
Where the appearance and assessment are consistent with a typical lipoma, for instance, neither treatment nor even follow-up may be needed.
By contrast, the approach may change where there is suspicion of GIST, growth, an ulcer developing over it, bleeding, suspicious EUS features or symptoms.
Where treatment is needed, removal by endoscopic or surgical methods may be considered according to the lesion’s features.
Is a follow-up endoscopy needed?
There is no single follow-up programme for every subepithelial lesion.
The decision is made by weighing together the lesion’s type + size + location + EUS features + tissue result + the patient’s clinical situation.
When should more care be taken?
More detailed assessment is needed if a subepithelial lesion is accompanied by
Bleeding · anaemia · black stools · difficulty swallowing · persistent vomiting · marked pain · unintended weight loss.
Remember
- A subepithelial lesion Does not mean cancer.
- Many subepithelial lesions Are harmless.
- Standard endoscopy Shows the surface of the lesion but cannot always determine its type.
- EUS Matters a great deal in assessing which layer of the wall it arises from and what its structure is.
- Not every lesion Needs a biopsy.
- Size and EUS features Matter in the decision about follow-up or treatment.
This is not enough to make a diagnosis
“Subepithelial lesion” on an endoscopy report does not on its own mean a malignant condition. The lesion’s location, size and endoscopic appearance are assessed; and in patients who need it, EUS and appropriate tissue sampling are used to find out what it is.
Sources
- Prof. Ali Tüzün İnce, MD