Angioinvasive Oncocytic Adrenocortical Carcinoma: Understanding Your Pathology Report

by Jason Wasserman MD PhD FRCPC
January 19, 2026

Angioinvasive oncocytic adrenocortical carcinoma is a rare type of adrenal gland cancer. It starts from the adrenal cortex, the outer layer of the adrenal gland that normally produces hormones such as cortisol and aldosterone.

This tumour is described as oncocytic because the cancer cells contain an unusually large number of mitochondria. Mitochondria are the parts of a cell that produce energy, and when they are very numerous, the cells appear large, granular, and pink under the microscope.

The tumour is called angioinvasive when cancer cells are found inside blood vessels. This feature is important because it increases the risk that cancer cells can spread to other parts of the body.

This article explains how this diagnosis is made, what features pathologists look for in the tissue, and how those findings help doctors estimate tumour behaviour and guide treatment.

What are the symptoms of angioinvasive oncocytic adrenocortical carcinoma?

The symptoms associated with oncocytic adrenocortical carcinoma vary from patient to patient. Some tumours cause symptoms because of their size and location, while others cause symptoms because they produce excess hormones. In some patients, the tumour is discovered incidentally on imaging performed for another reason.

When symptoms are related to tumour growth, they may include abdominal or flank pain, a feeling of fullness after eating small amounts, unexplained weight loss, or back pain caused by pressure on nearby organs.

When the tumour produces hormones, symptoms depend on the hormone involved. Excess cortisol can cause Cushing syndrome, with weight gain (especially in the face and trunk), muscle weakness, easy bruising, high blood pressure, diabetes, and osteoporosis. Excess aldosterone can cause Conn syndrome, leading to high blood pressure and low potassium levels, which may result in muscle weakness, cramps, or fatigue. Rarely, the tumour produces sex hormones, which can cause virilization (such as excess facial hair or voice deepening in women) or feminization (such as breast development in men).

What causes angioinvasive oncocytic adrenocortical carcinoma?

The exact cause is not always known, but this tumour develops due to genetic changes in adrenal cortical cells. These genetic changes affect how cells grow, divide, and respond to normal control signals.

Some people have an increased risk because of inherited cancer syndromes, such as Li–Fraumeni syndrome or Beckwith–Wiedemann syndrome. In most adults, however, the tumour develops sporadically, with no known family history. Environmental factors such as smoking have been linked to adrenal cortical tumours in general, but no single exposure has been proven to cause this specific tumour type directly.

How is this diagnosis made?

The diagnosis of angioinvasive oncocytic adrenocortical carcinoma is made by combining imaging studies, surgical findings, and a pathologist’s microscopic examination of the tumour. Additional tests, such as immunohistochemistry and markers of proliferation, help confirm the diagnosis and estimate the tumour’s aggressiveness.

Imaging

CT or MRI scans are usually performed first. Tumours suspicious for carcinoma are often large, solid, and heterogeneous, and may show areas of bleeding or tissue breakdown. Imaging also helps determine whether the tumour has grown into nearby structures or blood vessels.

Microscopic features

Under the microscope, oncocytic adrenocortical carcinoma is made of large tumour cells with abundant granular, pink cytoplasm, reflecting their high mitochondrial content. The cells are arranged in solid sheets, nests, or broad trabeculae rather than the orderly patterns seen in benign adrenal tumours.

Pathologists also carefully examine the edges of the tumour. Capsular invasion means the tumour has grown through the thin fibrous layer that normally surrounds the adrenal gland. Lymphatic invasion means tumour cells are found inside lymphatic channels. Both findings indicate more aggressive behaviour and increase the risk of spread.

Vascular invasion

Vascular invasion (angioinvasion) means tumour cells are seen inside blood vessels, often attached to the vessel wall or mixed with clot material. This is one of the most important features in adrenal cortical carcinoma because it provides a direct route for tumour cells to spread to distant organs such as the lungs or liver. Vascular invasion is associated with a worse prognosis.

Tumour grade

Oncocytic adrenocortical carcinomas are commonly divided into low-grade and high-grade based on the rate of tumour cell division. Faster-growing tumours tend to behave more aggressively.

One way to measure growth rate is mitotic count, the number of tumour cells observed dividing (mitotic figures) when the tissue is examined under the microscope. Pathologists count mitotic figures in a defined area (often reported as a number per 10 mm²).

In many practices, tumours are classified as:

• Low grade when there are 20 or fewer mitoses per 10 mm².

• High grade when there are more than 20 mitoses per 10 mm².

Another way to measure growth is the Ki-67 proliferation index, determined by immunohistochemistry. Ki-67 highlights tumour cells that are actively cycling. The result is reported as a percentage, usually measured in the most active area of the tumour (“hot spot”). For example, the report may state: “Ki-67 proliferation index: 8%” or “Ki-67: approximately 25% in hot spots.” Higher Ki-67 values are associated with worse prognosis and may influence decisions about additional therapy after surgery.

What is the Helsinki score?

The Helsinki score is a scoring system used by some pathology teams to help assess adrenal cortical tumours. It combines three features into a single score: tumour mitotic activity, tumour necrosis, and the Ki-67 proliferation index.

The Helsinki score is calculated as follows: (3 × mitotic count) + (5 × necrosis) + (Ki-67 percentage).

Necrosis means tumour cell death. It is scored as present or absent (if present, it contributes points), and Ki-67 is added as the measured percentage from the tumour hot spot.

The result is reported as a single number (for example, “Helsinki score: 12”). A score greater than 8.5 supports the diagnosis of adrenocortical carcinoma in the appropriate setting. Higher values are associated with more aggressive behaviour, and some centres use higher cutoffs (e.g.,>17) to identify particularly high-risk tumours.

Weiss score

The Weiss score is another system pathologists use to distinguish benign adrenal tumours from carcinomas. It is based on nine microscopic features, including mitotic activity, necrosis, growth pattern, and invasion into surrounding tissues or vessels.

Each feature scores one point. A total score of 3 or more supports a diagnosis of adrenocortical carcinoma, while a lower score favours adenoma. The Weiss score is especially useful for conventional (non-oncocytic) tumours, while modified systems are often used for oncocytic tumours.

Surgical margins

A margin is the edge of tissue cut by the surgeon when the tumour is removed. Pathologists examine these edges to see if tumour cells are present.

A negative margin means no tumour cells are seen at the cut edge and suggests the tumour was removed entirely. A positive margin means tumour cells reach the edge of the specimen, increasing the risk that cancer cells remain in the body and that the tumour could recur. Margin status is an important factor when deciding whether additional treatment is needed.

What happens after the diagnosis?

After diagnosis, doctors consider tumour size, invasion, grade, scores such as the Helsinki or Weiss scores, and whether the tumour was removed entirely. Additional imaging, hormone testing, and sometimes genetic counselling are recommended. Patients with aggressive features usually require close long-term follow-up, and some may benefit from additional therapies.

Questions to ask your doctor

• Is my tumour low-grade or high-grade?

• Was vascular invasion identified?

• What were my Helsinki and Weiss scores, and what do they mean?

• Were the surgical margins clear?

• Do I need genetic testing or additional imaging?

• What follow-up plan do you recommend?