Rare skin tumors

What are rare skin tumors?

Skin cancer is one of the most common types of cancer, even in Switzerland. Doctors distinguish between different types of skin cancer: basal cell carcinoma (basal cell cancer, basal cell carcinoma) is the most common, followed by squamous cell carcinoma (spinal cell carcinoma, spinalioma) – both fall under the term “white skin cancer”. There is also black skin cancer (malignant melanoma), which is considered to be particularly malignant and aggressive. These three forms of skin cancer account for the majority of cases.

However, experts know of even more malignant skin tumors that only affect very few people and which they therefore group together under the heading “rare skin tumors”. They originate from different cells and tissues. Examples are:

• Cutaneous sarcomas, e.g. dermatofibrosarcoma protuberans (the most common cutaneous sarcoma), undifferentiated pleomorphic sarcoma (also malignant fibrous histiocytoma), atypical fibroxanthoma, angiosarcoma, leiomyosarcoma or carposi sarcoma
• Merkel cell carcinoma – it probably originates in the stem cells of the epidermis and dermis or in early B cells of the immune system. Researchers previously assumed that Merkel cell carcinoma originated in the Merkel cells, which are important for the sense of touch.
• Liposarcoma – it originates from fatty tissue

The symptoms of rare skin tumors are usually skin changes, but these can vary greatly and affect different parts of the body. For example, discoloration and lumps can form on the skin.

Because these skin tumors are so rare, many doctors hardly ever come into contact with them in their daily practice. In addition, they are often difficult to recognize and not easy to distinguish from other skin diseases. Some patients are therefore only diagnosed late, when the skin tumor is already more advanced. In addition, skin tumors are dangerous in different ways – some grow slowly, while others spread quickly and form metastases in other organs.

The treatment of rare skin tumors usually consists of surgery. Doctors try to remove the malignant tumor as completely as possible. Sometimes other treatments are also used, such as radiotherapy.

Rare skin tumors - frequency and age

Rare skin tumors only affect a few people, as the name suggests. In the European Union, experts speak of a rare disease if it affects no more than five in 10,000 people. The age for rare skin tumors can also vary – from young to old. And in principle, these tumors can affect people of any gender.

Some facts and figures on selected rare skin tumors:

• Dermatofibrosarcoma protuberans: This is the most common cutaneous sarcoma. On average, patients are 40 years old when they are diagnosed. Extremely rarely, dermatofibrosarcoma protuberans can also develop in children. The female and male sexes are affected about equally often.
• Undifferentiated pleomorphic sarcoma: Approximately one to nine people in 100,000 develop the disease. Children, adolescents and adults can be equally affected.
• Merkel cell carcinoma: This skin tumor usually occurs in older people from the age of 70. In recent years, the number of cases in Europe and the USA has risen sharply. Researchers suspect that this is due to an infection with the so-called Merkel cell polyoma virus. Both sexes develop Merkel cell carcinoma at roughly the same rate. The malignant tumor affects around 0.4 out of every 100,000 inhabitants each year.
• Angiosarcoma: This tumor accounts for about five percent of cutaneous sarcomas. It usually forms in the superficial soft tissue and the skin (60 percent), especially in the head and neck area and on the scalp.
• Kaposi’s sarcoma: There are several forms – one of which is associated with HIV infection. People of any age can fall ill.
• Liposarcoma: This tumor accounts for approximately 20 percent of all malignant tumors of the soft tissue. Men over the age of 50 are particularly often affected.

Rare skin tumors: causes vary

There are various rare skin tumors, which in turn can have different causes. Sometimes the reasons and the way they come about are still unknown. In any case, there is no “one” cause of cancer; several factors usually have to interact for cancer to develop. Experts are also aware of a number of risk factors that promote the development of cancer. The most important causes of rare skin tumors at a glance.

• Dermatofibrosarcoma protuberans: The tumor originates from the connective tissue. However, the exact pathogenesis of this skin cancer is not yet known. Genes probably play a role.
• Undifferentiated pleomorphic sarcoma: The pathogenesis of the disease has not yet been clarified. In rare cases, malignant fibrous histiocytoma runs in families and there are affected individuals in different generations. Genes and heredity are therefore probably involved.
• Merkel cell carcinomaExperts suspect that Merkel cell carcinoma is linked to a virus – the so-called Merkel cell polyoma virus (MCPyV). In around 80 percent of all patients with this diagnosis, this virus can be detected in the tumor tissue. However, many people harbor MCPyV without developing Merkel cell carcinoma. Other risk factors are therefore probably involved. These include, for example, older age, exposure to strong UV radiation in the past and a weakened immune system (e.g. in the case of HIV or after an organ transplant). The starting point for Merkel cell carcinoma is probably not the Merkel cells in the skin, but stem cells of the epidermis and dermis or early B cells of the immune system.
• Angiosarcoma: This can be caused by long-term lymphoedema, for example in women with breast cancer following an operation. Researchers also suspect that ionizing radiation (e.g. radiotherapy for breast cancer) and genetic defects (BRCA1 and BRCA2) are possible causes of angiosarcoma. Other possible “precursors” can be AV fistulas (e.g. after dialysis). It is still unclear whether carcinogenic substances, UV radiation and foreign bodies play a role in angiosarcoma. Only rarely do angiosarcomas develop from benign skin tumors, such as leiomyomas or neurofibromas.
• Kaposi’s sarcomaThere are various forms of Kaposi’s sarcoma with different causes. A suppressed immune system (e.g. immunosuppression after a transplant) and infection with the HI virus probably play a role. This is also associated with immunodeficiency.
• Liposarcomas: These presumably develop when embryonic precursor cells of the fatty tissue degenerate – not from lipomas (benign tumors).

Symptoms: Rare skin tumors cause skin changes

The symptoms of rare skin tumors depend on the type of malignant tumor. Some skin tumors grow slowly and only rarely form metastases in other organs. Others are aggressive and develop quickly. All rare skin tumors have skin changes in common, which can appear on different parts of the body. However, they are often so unspecific that most people do not immediately think of a malignant skin tumor. It can also be caused by other harmless skin diseases. Possible symptoms of rare skin tumors at a glance.

Dermatofibrosarcoma protuberans – Symptoms

This skin tumor grows slowly over years or decades and destroys the tissue locally. It only rarely forms metastases in other organs. Asymmetrical stolons that grow horizontally are typical. The tumor also penetrates into deeper structures. A dermatofibrosarcoma protuberans often presents as a skin-colored, yellow, brown or reddish rough tumor that does not cause pain. Single or multiple tumor nodules may be present. This skin cancer forms preferentially on the extremities, trunk, head or neck.

Undifferentiated pleomorphic sarcoma – symptoms

As with other sarcomas, there are hardly any characteristic symptoms that would indicate an undifferentiated pleomorphic sarcoma. A lump often forms, which can develop into an ulcer over time. If the tumor slowly enlarges, it can cause pain in some cases. The malignant fibrous histiocytoma often forms on the hairy scalp, forehead, temples and extremities.

Merkel cell carcinoma – Symptoms

Merkel cell carcinomas occur most frequently in the head and neck as well as on the arms and legs. They form less frequently on the trunk. Merkel cell carcinoma can be recognized by these signs:

• reddish to violet-bluish coloration
• spherical shape
• Smooth and glossy surface
• Rough consistency
• sometimes spots, especially on the torso
• rarely in the late stages: ulcers (ulcerations)

Merkel cell carcinomas are often aggressive and grow quickly. Doctors use the abbreviation “AEIOU” to describe the characteristics of these tumors:

• A = asymptomatic/painless
• E = rapid expansion (expansion)
• I = Immunosuppressed patients (suppressed immune system)
• O = older patients over 50 years of age
• U = Tumor has formed in the area of skin exposed to UV radiation (light skin).

Angiosarcoma – Symptoms

Angiosarcomas of the skin mainly form in the area of the head and neck and on the scalp. Skin discoloration and changes are often the only visible sign of angiosarcoma at first. The malignant skin tumor is therefore easy to confuse with other skin diseases, such as hives (urticaria), rosacea or inflammatory facial dermatosis.

People with angiosarcoma often experience no symptoms for a long time. Those affected usually feel affected by bleeding or swelling in the facial area as the disease progresses. If distant metastases are already present in other organs, pain may occur. Such cancer metastases form mainly in the lymph nodes and in the lungs, liver and spleen.

Kaposi’s sarcoma – symptoms

Depending on its form, carposarcoma can affect different parts of the body. If it is associated with an HIV infection, the symptoms often appear on the face and oral mucosa. The classic Kaposi’s sarcoma affects the lower extremities, more rarely the hands, ears, nose or penis.

The following symptoms indicate a carposi-sarcoma:

• brown-reddish to bluish spots or lumps
• Massive water retention (edema) and extensive swelling – often entire extremities and the face are affected
• Hemorrhages
• Tissue death (necrosis)
• bleeding ulcers

In all four forms of Kaposi’s sarcoma, most patients do not experience any symptoms for a long time. They often only feel impaired when ulcers, bleeding and swelling occur.

Liposarcoma – Symptoms

Liposarcoma usually forms on the trunk of the body and the lower extremities. There are isolated or multiple cancer foci. Lumps develop under the skin that do not cause any pain. They are difficult to distinguish from benign lipomas. Liposarcomas grow relatively quickly and tend to spread via the lymphatic system and bloodstream, forming metastases in other organs. This is usually followed by other symptoms.

Rare skin tumors: Diagnosis with us

The diagnosis of rare skin tumors begins with a discussion of your medical history, the anamnesis. We ask you a few questions, among others:

• What are your symptoms?
• When did the complaints first appear?
• How pronounced are they?
• Have the symptoms improved again in the meantime or have they increased continuously?
• Do you have a known underlying disease? If yes: Which one and since when does it exist?
• Are you taking any medications? If yes: Which and since when?
• Is there cancer in your family?
• Have you undergone a transplant or other therapy in the past?

These and other questions help us to make an initial assessment. This is usually followed by a physical examination, during which the doctor examines the skin and palpates the body for changes. A blood test, in which laboratory doctors determine the blood values, is usually also standard.

Only a tissue sample (biopsy) provides certainty as to whether a rare skin tumor is present. We use a fine needle to remove cells from the suspicious area. This is then analyzed by a pathologist. Under the microscope, benign and malignant cells can be distinguished with a high degree of certainty.

Further information is provided by imaging procedures such as ultrasound (sonography), computer tomography (CT) or magnetic resonance imaging (MRI = magnetic resonance imaging). They show the location, size and spread of the tumor.

We use the so-called TNM classification for cancers in order to characterize and classify the tumour more precisely. The subsequent treatment also depends on this. The letter T stands for tumor size, N for affected lymph nodes (node) and M for metastases in other organs. We can also determine how aggressive the tumor is. The so-called grading indicates how similar the cancer cells are to healthy cells.

Rare skin tumors: prevention, early detection, prognosis

In many cases, the causes of rare skin tumors have not yet been researched in detail. Therefore, you can hardly prevent them. However, risk factors are known for some malignant tumors of the skin, such as intensive UV radiation. And this is where you can help yourself: Always make sure you use adequate sun protection and avoid frequent, prolonged sunbathing.

It is also important to have a strong immune system that can defend itself well against pathogens. However, if the rare skin tumor is associated with an HIV infection, organ transplant or breast cancer treatment, preventive measures are also hardly possible.

Special measures for early detection in medical practices are also not known. If you already suffer from a disease, have it checked regularly by us as part of your aftercare. This may allow a rare skin tumor to be detected at an early stage.

Otherwise, the general advice always applies: consult your doctor promptly if you notice skin changes of any kind. A visit to the doctor is also advisable if you suffer from other complaints that you cannot explain.

Progression and prognosis of rare skin tumors

The course and prognosis of rare skin tumors cannot be generally predicted. Both depend on the type of skin tumor, its size, aggressiveness and spread. Some skin tumors grow slowly and rarely metastasize to other organs. The prognosis is then generally more favorable.

Other tumors of the skin are more aggressive, grow rapidly, spread more quickly and form cancer metastases in other organs. Then the prognosis is less favorable. Your general state of health, age and other existing illnesses also play a role in the prognosis and course of the disease.