Pleural tumors

What are pleural tumors?

The pleura consists of two thin membranes, the two pleural sheets. The parietal pleura lines the inside of the chest wall, while the visceral pleura covers and protects the lungs. Between them lies the pleural cavity, which contains little fluid and prevents the two leaves from rubbing against each other. Due to the negative pressure in the pleural cavity, both leaves lie close together and support the lungs in breathing.

Even if the pleura is only a thin layer of connective tissue, tumors can form here. However, pleural tumors are comparatively very rare. We differentiate between pleural tumors on the basis of various criteria.

Primary and secondary pleural tumors

We classify pleural tumors according to their place of origin:

• Primary pleural tumors form on the pleura from the outset and originate there. They are very rare and account for only about three percent of all pleural tumors. 80 percent of them originate from the pleura and around 20 percent from the pleura. Such primary malignant tumors affect men more often than women. On average, they fall ill at around 63 years of age. They often form under the influence of asbestos.
• Secondary pleural tumors, on the other hand, are caused by another cancer, often an existing lung cancer (lung carcinoma). The lungs and the pleura are in close proximity to each other. Lung cancer spreads quickly and spreads to neighboring organs and tissue – it forms cancer metastases. We speak of pleural carcinomatosis. Secondary pleural tumors account for around 97 percent of all pleural tumors – so they are much more common than primary tumors.

Pleural tumors: benign or malignant

The causes of pleural tumors can be very different. Benign tumors of the pleura often arise from fatty, connective or vascular tissue. It is not clear why these cells change. In the case of solitary fibrous pleural tumors (fibromas), neither a genetic predisposition nor a connection with risk factors such as asbestos, smoking or other environmental influences can be proven. Even if these tumors are initially benign, there is a risk that they will turn into malignant pleural tumors. This is not uncommon in fibrous tumors – it is the case in around 25 percent of tumors.

Secondary malignant pleural tumors are based on cancer of another organ. For example, tumor cells in the following types of cancer can also migrate to the pleura and settle there:

• Lung cancer (lung carcinoma) – most common because the lungs are in the immediate vicinity
• Breast cancer (breast carcinoma)
• Ovarian cancer (ovarian carcinoma)
• Stomach cancer (gastric carcinoma)
• Pancreatic cancer (pancreatic carcinoma)
• Black skin cancer (malignant melanoma)
• Sarcomas: cancer of the connective and supporting tissue

Primary benign pleural tumors include, for example:

• Lipomas: They originate from fatty tissue cells and are the most common benign tumors
• Fibromas (solitary fibrous tumors of the pleura = SFT): The cells of the connective tissue proliferate. In around 80 percent of cases, these tumors are benign, but around a quarter develop into malignant tumors. Most (approx. 70 percent) originate from the pleura and have a stalk. Tumors that grow into the lungs or originate in the pleura (at the mediastinum or diaphragm) are often malignant.
• Benign pleural mesothelioma: In rare cases, pleural mesothelioma is benign; in most cases it is malignant.
• Angiomas are malformations of the blood vessels.

Primary malignant pleural tumors are, for example:

• Pleural mesothelioma – this term covers all malignant pleural tumors. They often originate from the pleura.
• Lymphomas
• Sarcomas (fibro-, angiosarcomas and liposarcomas) – they are extremely rare.

Primary malignant pleural mesothelioma can develop if a person handles asbestos for a long time and inhales the harmful substance, for example at work. However, these malignant tumors develop over longer periods of several decades (20 to 40 years) after exposure to asbestos. These malignant pleural tumors are considered an occupational disease. However, it is often not easy to prove a connection with asbestos work after many years.

Symptoms: Pleural tumors often remain "silent"

Many of those affected do not notice pleural tumors. More than half of all people with tumors in the pleura experience no symptoms. This is especially true for benign tumors. We often find them by chance during another examination, for example an X-ray. If the tumor remains confined to the visceral pleura, there is no pain, as only the parietal pleura is sensitive to pain.

When symptoms occur, they are usually as follows:

• Pain or feeling of pressure in the chest
• Shortness of breath, shortness of breath
• Chronic cough – mostly dry cough
• Hypertrophic osteoarthropathy: painful swelling of the extremities, drumstick fingers and toes, watch glass nails
• rarely hypoglycaemia (low blood sugar levels): Some benign or malignant tumors are hormonally active.
• Rarely milk flow from the female breast outside of pregnancy and breastfeeding (galactorrhea)
• Bleeding of the pleura, especially in fibrous tumors of the connective tissue
• Pleural effusion, especially with malignant pleural tumors
• General cancer symptoms in advanced stages: tiredness, exhaustion, reduced performance, loss of appetite, unintentional weight loss

Pleural tumors: Diagnosis with us

In addition to the medical history (malignant diseases), including determining contact with potentially harmful substances (dust, asbestos), the clinical examination (inspection, auscultation) also provides initial clues (e.g. movement of the chest during breathing, symmetry).

Examinations for pleural tumors

Various imaging procedures and other diagnostic methods can be used to track down possible pleural tumors. These include:

• Ultrasound (sonography): Ultrasound waves can be used to detect fluid-filled cavities, such as a pleural effusion. It is often associated with malignant diseases.
• X-ray examination of the chest (chest X-ray): We can visualize thickening of the pleura (pleural callus) or a pleural effusion.
• Computed tomography (CT): An X-ray examination in which radiologists create detailed cross-sectional images of the chest. CT can, for example, show small nodular thickenings. In the case of a malignant pleural tumor, we can also determine the size and spread of the cancer or the involvement of lymph nodes. A density measurement during CT can identify lipomas.
• Tissue sample (biopsy): We use a fine needle to take a tissue sample from the suspicious area. We either carry out the biopsy as part of a thoracoscopy or with the help of ultrasound or a CT scan. The tissue is then examined under a microscope by a pathologist. They can distinguish between benign and malignant cells very precisely.

Pleural tumors: prevention, early detection, prognosis

You cannot really prevent pleural tumors except by avoiding noxious substances such as smoking and exposure to asbestos, because in most cases no exact cause can be determined. The most important factor is the avoidance of noxious substances (nicotine, asbestos) and the use of protective measures (mask, extraction of contaminated ambient air).

There are also no special measures for the early detection of pleural tumors. Generally speaking, if you have a cough that won’t go away, come and see us. A prompt visit is also advisable in the event of chest pain or shortness of breath.

Course and prognosis of pleural tumors

The course and prognosis of pleural tumors cannot be generally predicted. Nor can we make any general statements about life expectancy and chances of recovery because pleural tumors can be very different and depend very much on the underlying disease (in the case of secondary pleural tumors).

Benign tumors can often be removed during surgery and the prognosis is favorable. The operation should always take place before the benign tumor has turned malignant. This is not so rare. In the case of benign pleural mesothelioma, regular follow-up checks are also important. Even after many years, there is a risk that the tumor will return (relapse).

Pleural tumors: Interdisciplinary treatment

The treatment of pleural tumors belongs in the hands of experienced physicians from various specialties, such as surgeons, pulmonologists, oncologists and radiation oncologists. At the USZ, they work closely together as a team and discuss each case individually.