Endometrial Hyperplasia Without Atypia: Understanding Your Pathology Report

Section Editor: Kianoosh Keyhanian MD FRCPC
September 1, 2026

Endometrial hyperplasia without atypia is a noncancerous (benign) condition in which the lining of the uterus becomes thicker than normal. The lining is called the endometrium. In this condition, the endometrial glands grow and multiply more than they should, so they become crowded together.

The words “without atypia” carry most of the meaning. They tell you that the cells lining the glands look normal, even though there are too many of them. Atypia means the cells themselves look abnormal, and its presence substantially changes the diagnosis and treatment. Pathologists divide endometrial hyperplasia into two groups: without atypia and with atypia.

This is the lower-risk of the two. Most cases go away, either on their own or with treatment, and fewer than 5 in 100 women with this diagnosis develop endometrial cancer over the following 20 years. This article will help you understand what this diagnosis means on your pathology report, what each term means, and why it matters for your care.

What causes endometrial hyperplasia without atypia?

This condition results from an imbalance between the two hormones that control the lining of the uterus. Estrogen makes the lining grow. Progesterone matures it and prepares it to shed. In a normal cycle, estrogen dominates the first half, called the proliferative phase, and progesterone takes over after ovulation, in the secretory phase. If no pregnancy occurs, both hormones fall, and the lining sheds.

When estrogen acts on the lining without enough progesterone to balance it, the lining keeps growing and does not shed properly. Over time,e the glands become crowded, which is what hyperplasia describes. Situations that produce this pattern include:

Cycles without ovulation — Progesterone is only made after an egg is released. When ovulation does not happen, the lining sees estrogen alone. This is common in polycystic ovary syndrome and during the years approaching menopause.
Excess body weight — Fat tissue converts other hormones into estrogen, so higher body weight means higher estrogen exposure. This is the most common contributing factor after menopause.
Estrogen without progesterone — Hormone therapy containing estrogen alone, taken by someone who still has a uterus, produces exactly this imbalance.
Tamoxifen — A medication used in breast cancer treatment. It blocks estrogen in the breast but acts like estrogen in the uterus.
Estrogen-producing ovarian tumors — Uncommon, but a thecoma or a granulosa cell tumor of the ovary can produce enough estrogen to cause this.

What are the symptoms?

The main symptom is abnormal bleeding from the uterus, and it is usually what leads to the biopsy. This may take several forms.

Heavy or prolonged periods — Bleeding that is heavier or lasts longer than usual for you.
Bleeding between periods — Spotting or bleeding when a period is not expected.
Irregular cycles — Periods that are unpredictable, or long gaps followed by heavy bleeding.
Bleeding after menopause — Any bleeding after menopause should be assessed promptly, whatever the eventual cause turns out to be.

Some people have no symptoms, and the finding turns up in tissue removed for another reason.

How is the diagnosis made?

A pathologist makes the diagnosis by examining a sample of the endometrium under a microscope. The sample is usually obtained by endometrial biopsy, a brief clinic procedure in which a thin, flexible tube collects tissue from the lining. It may also come from a dilation and curettage, from a hysteroscopy, or from a uterus removed at surgery.

An ultrasound is often done first and may show a thickened lining, but thickness on a scan cannot distinguish hyperplasia from other causes. Only examination of the tissue can do that.

The pathologist’s task is to decide which of several diagnoses fits: a normal lining out of step with the cycle, hyperplasia without atypia, hyperplasia with atypia, or cancer. That decision depends on how crowded the glands are and how the lining cells look.

What does endometrial hyperplasia without atypia look like under the microscope?

Endometrial hyperplasia without atypia is a thickened lining of the uterus in which the glands are crowded, but the cells lining them remain normal. Under the microscope, the pathologist looks for the following features.

Crowded glands — The endometrial glands sit closer together than normal, with less supporting tissue between them. The degree of crowding separates hyperplasia from a normal lining.
Irregular gland shapes — The glands vary in size and shape, and may be branched or dilated rather than evenly round.
Normal lining cells — The cells forming the glands look like ordinary endometrial cells. Their nuclei are uniform and evenly spaced. This finding places the diagnosis in the “without atypia” group.
No invasion — The glands stay within the lining and do not grow into the muscle wall of the uterus.
Breakdown and bleeding — Areas where the lining is shedding are often present and explain the bleeding that prompted the biopsy.

Endometrial hyperplasia without atypia

How is this different from other endometrial diagnoses?

Endometrial hyperplasia without atypia falls within a range of diagnoses that differ in gland crowding and cell appearance. Your report may mention any of the following.

Disordered proliferative endometrium — A milder change, with slightly irregular glands but not enough crowding for hyperplasia. It reflects the same hormonal imbalance and is not precancerous. The line between this and hyperplasia without atypia is a matter of degree, and pathologists do not always draw it in the same place.
Endometrial hyperplasia without atypia — Crowded glands, normal cells. The diagnosis described in this article.
Atypical hyperplasia — Crowded glands together with abnormal-looking cells. Atypical endometrial hyperplasia is also called endometrioid intraepithelial neoplasia, or EIN. It is precancerous, and roughly 28 in 100 women develop cancer over 20 years without treatment.
Endometrioid carcinoma — Cancer of the lining of the uterus. Endometrioid carcinoma is the most common type and is often found early because it causes bleeding.

Older reports use different words for the same condition. Terms such as simple hyperplasia and complex hyperplasia without atypia come from a previous four-part system that the current two-group system has replaced. If you have a report from a few years ago using those terms, both fall under what is now called hyperplasia without atypia.

Can endometrial hyperplasia without atypia turn into cancer?

It can, but it usually does not. Fewer than 5 in 100 women with this diagnosis develop endometrial cancer over the following 20 years. Most cases go the other way and resolve, and about 3 in 4 regress without any treatment when the underlying cause is addressed.

The comparison with the other group is worth making, because the two are often confused. Atypical hyperplasia carries a risk of around 28 in 100 over the same period, roughly six times higher, and is managed quite differently. If your report says “without atypia,” you are in the lower-risk group.

Risk is higher for those whose estrogen exposure continues unchecked, and for those who do not complete follow-up. This is why treatment focuses on correcting the imbalance and confirming that the lining has returned to normal.

How is endometrial hyperplasia without atypia treated and followed?

Treatment aims to restore the balance between estrogen and progesterone, and to confirm afterward that the lining has returned to normal. The approach depends on your symptoms, your age, and whether you hope to become pregnant.

A hormonal IUD — A levonorgestrel-releasing intrauterine device is the recommended first choice. It delivers progestin directly to the lining, works better than tablets, and causes fewer side effects.
Progestin tablets — An alternative when an IUD is not suitable or not wanted.
Observation — Reasonable in some situations, particularly when a reversible cause such as estrogen-only hormone therapy can be corrected. Regression is more likely with treatment than with observation alone, so make this decision with your doctor.
Addressing the cause — Stopping estrogen-only hormone therapy, managing polycystic ovary syndrome, or weight reduction where relevant. Treating the lining without addressing the cause invites recurrence.
Hysterectomy — Not the first choice for this diagnosis. Consider it when the condition does not resolve after treatment, returns, or progresses to atypia. It is also an option when bleeding cannot be controlled, or when someone prefers not to continue with surveillance.

Follow-up biopsies are part of the treatment, not an optional extra. Treatment is usually given for at least six months, with biopsies at intervals until two consecutive samples come back normal. If you have the IUD, it can stay in place during the biopsy, and keeping it for up to five years reduces the chance of the condition returning. Report any new abnormal bleeding after discharge, since it can be the first sign of recurrence.

What other findings may be described in the report?

Your report may describe other features of the lining alongside the hyperplasia.

Endometrial polyp — A benign overgrowth of the lining, commonly found alongside hyperplasia and reported separately.
Breakdown and bleeding — Changes in a lining that is shedding, which often explain the symptoms.
Chronic inflammation — If plasma cells are present, the report may also diagnose chronic endometritis.
Sample adequacy — The report may note that the sample was scant or fragmented. This does not mean the diagnosis is wrong, but it may mean a repeat sample is needed to be confident nothing was missed.
Metaplasia — Areas where the lining cells have taken on a different but still normal appearance. This is common and not precancerous.

Questions to ask your doctor

Does my report say hyperplasia without atypia, or with atypia?
What do you think caused the hormonal imbalance in my case?
Do you recommend the hormonal IUD, tablets, or observation, and why?
How long should treatment continue?
When will I have a repeat biopsy, and how many will I need?
Was the sample adequate, or should it be repeated?
Was an endometrial polyp or any other finding reported?
Should I stop or change my hormone therapy?
Does this affect my chances of becoming pregnant?
How likely is this to come back after treatment?
What is my risk of developing endometrial cancer?
Would a hysterectomy be recommended in my situation?
What symptoms should prompt me to contact you?