Schneiderian papilloma

by Emilija Todorovic MD FRCPC
June 5, 2022


What is a Schneiderian papilloma?

A Schneiderian papilloma is a non-cancerous tumour that starts from the tissue that lines the inside of the nasal cavity and paranasal sinus. Pathologists divide Schneiderian papillomas into three types: inverted, exophytic, and oncocytic (see below for more information). Schneiderian papillomas can grow into surrounding tissues but the tumour cells are not able to spread to other parts of the body. Another name for Schneiderian papilloma is sinonasal papilloma.

What are the symptoms of a Schneiderian papilloma?

Schneiderian papillomas often grow as finger-like projections outwards and can block the nasal passages. As a result, the tumour can cause symptoms such as:

  • Blockage of the nose
  • Runny nose
  • Bleeding
  • Repeated infections
  • Pain
  • Headache

Types of Schneiderian papillomas

Schneiderian papillomas are divided into three types – inverted, exophytic, and oncocytic – based on how the tumour looks when examined under the microscope. The tumour type is important because the inverted type is more likely to grow and damage surrounding tissues if it is not completely removed. The inverted type is also associated with a high risk of developing a type of cancer called squamous cell carcinoma.

Inverted type Schneiderian papilloma

Inverted Schneiderian papilloma is the most common type of Schneiderian papilloma. It typically affects adults over the age of 50 years and most arise in the wall of the maxillary sinus and the lateral wall of the nasal cavity. Less commonly, the tumour will start in the wall of the ethmoid, frontal, or sphenoid sinus.

When examined under the microscope, the tumour is seen growing downwards from the surface mucosa, which is why they are called inverted. The tumour is made up of a combination of squamous cells and mucin-producing mucocytes. Specialized immune cells called neutrophils are also seen.

inverted sinonasal papilloma

While it is considered a non-cancerous tumour, an inverted Schneiderian papilloma can cause significant damage to surrounding tissues as it grows. This can include the cartilage of the nose and bones of the face. In addition, a small number of inverted Schneiderian papillomas can change over time into a type of cancer called squamous cell carcinoma (see sections below). For these reasons, all inverted type Schneiderian papilomas should be removed completely.

Exophytic type Schneiderian papilloma

Exophytic Schneiderian papillomas tend to occur more often in people less than 50 years of age and are twice as common in men than women. It almost always starts on the medial wall of the nasal cavity near the septum.

When examined under the microscope the tumour is seen growing outwards from the surface of the mucosa in long finger-like projections of tissue. Pathologists call these finger-like projections a papillary pattern of growth. The tumour is made up of a combination of squamous cells and mucin-producing mucocytes. Specialized immune cells called neutrophils are also seen.

Oncocytic type Schneiderian papilloma

Oncocytic Schneiderian papillomas are more common in people over the age of 50 years and affect men and women equally. This type of Schneiderian papilloma is more likely to start on the lateral wall of the nasal cavity although it can also start on the wall of a sinus. When examined under the microscope, the tumour is made up of large pink cells. Pathologists describe these types of cells as oncocytic.

How is the diagnosis of Schneiderian papilloma made?

The diagnosis of Schneiderian papilloma is usually made after a small tissue sample is removed in a procedure called a biopsy. The tumour is then removed completely in a procedure called a resection. Your pathologist will carefully examine the entire tumour to look for a pre-cancerous change called dysplasia or a type of cancer called squamous cell carcinoma.

Dysplasia in a Schneiderian papilloma

Dysplasia is an abnormal pattern of growth that can change into cancer over time. Pathologists divide dysplasia into grade – low grade dysplasia and high grade dysplasia – and the risk of developing cancer is greater when high grade dysplasia is seen.

Although rare, dysplasia can be seen in some Schneiderian papillomas. For this reason, the entire Schneiderian papilloma needs to be examined closely for any evidence of dysplasia and when seen, it will be described in your pathology report.

Cancer developing from a Schneiderian papilloma

Schneiderian papillomas are non-cancerous tumours. However, over time, a cancerous tumour can develop from the cells in a Schneiderian papilloma. The most common type of cancer to develop from a Schneiderian papilloma is called squamous cell carcinoma. Carcinoma ex Schneiderian papilloma is the term pathologists use to describe a cancer such as squamous cell carcinoma that develops from a Schneiderian papilloma.

Most cancerous tumours develop from a precancerous change called dysplasia (see Dysplasia section above). Both dysplasia and cancer are more likely to develop in an inverted type Schneiderian papilloma and they are very rare in the exophytic or oncocytic types.

Cancerous tumours that develop from a Schneiderian papilloma tend to behave in an aggressive fashion. For example, the cancerous tumour is more likely to grow into parts of the head surrounding the sinonasal tract. Similar to other types of cancer, the cells in a cancerous tumour that develops from a Schneiderian papilloma are also able to spread to other parts of the body.

Margins

A margin is any tissue that was cut by the surgeon in order to remove the tumour from your body. Whenever possible, surgeons will try to cut tissue outside of the tumour to reduce the risk that any tumour cells will be left behind after the tumour is removed.

Margin

A negative margin means there were no tumour cells at the very edge of the cut tissue. A margin is considered positive when there are tumour cells at the very edge of the cut tissue. A positive margin is associated with a higher risk that the tumour will grow back (recur) in the same site after treatment.

Because Schneiderian papillomas are often removed in multiple pieces, your pathologist may not be able to reliably assess the margins of the tumour. For that reason, most pathology reports for Schneiderian papillomas do not have information about margins.

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