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Kaposi's sarcoma is a malignant neoplasm of soft tissues of vascular origin that affects the skin, mucous membranes and internal organs. Sarcomas are made up of clusters of spindle cells, abnormal blood vessels, extravasated erythrocytes (i.e. those that have passed beyond the blood vessels) and leukocyte infiltration.

Kaposi's sarcomais a malignant neoplasm of vascular origin. It arises and develops multifocal from cells of lymphatic and blood vessels and often forms extensive purple tumors.

More than 90 percent of Kaposi's sarcoma patients are carriers of the HHV-8 virus.

Kaposi's sarcoma is a rare neoplasm in the entire population, but its incidence depends largely on the geographic region and clinical presentation.

A total of 44,000 cases were reported in 2012, 85% of which occurred in the African region.

Epidemiological studies in Europe have shown an incidence of 0.3 cases per 100,000 people per year, making Kaposi's sarcoma arare cancer .

Based on the clinical picture and epidemiological data, 4 forms of Kaposi's sarcoma are distinguished:

  • classic figure- most often affects older men in the Mediterranean basin
  • endemic form- refers to cases recorded in central Africa
  • epidemic figure- related to AIDS
  • iatrogenic form- most common after immunosuppressive treatment or organ transplantation

The last two forms of sarcoma are most common in Poland.

The classic character most often affects men aged 60-70 in the Mediterranean region, i.e. Israel, Italy, Greece and Turkey.

The epidemic type is closely related to HIV transmission, it is believed that about 30% of untreated HIV carriers will develop Kaposi's sarcoma, but thanks to the introduction of anti-HIV drugs, it was possible to significantly reduce the incidence of this cancer in group of hosts.

Kaposi's sarcoma - causes

The causes of Kaposi's sarcoma are not fully understood.

A feature common to all types of sarcoma is the infection and activation of vascular cells by the HHV-8 virus, i.e. the oncogenic herpes virus type 8, also known as KSHV (Kaposi sarcoma associated herpes virus).

Studies have shown that 80-100% of Kaposi's sarcoma patients have antibodies to the HHV-8 virus, while in the general population this percentage is around 1%.

Another argument supporting the association of HHV-8 infection with sarcoma is the fact that HIV-8 antibodies have been reported to be positive for HHV-8 several weeks or even months before the onset of sarcoma symptoms.

HHV-8 virus infects the he alth of an endothelial cell (the cells that line the inside of blood vessels) and then goes into a dormant form. The activating factors that cause the virus to multiply include:

  • inflammation
  • use of immunosuppressants after organ transplants
  • HIV virus
  • environmental factors, which include bites by bloodsucking insects in the region of Africa, which is the cause of endemic Kaposi's sarcoma

When activating factors appear, the virus multiplies in successive, he althy cells.

Some of them convert normal cells to spindle cells, characteristic of Kaposi's sarcoma. This process is called neoplastic transformation.

Dissemination of abnormal cells causes clinical symptoms specific to the sarcoma.

An important function in the growth of Kaposi's sarcoma is played by the process of neoangiogenesis in the tumor area, i.e. the formation of new, often incorrectly formed blood vessels, which allows for blood supply to the tumor and its growth.

HHV-8 virus infection is required for the appearance of Kaposi's sarcoma, followed by the occurrence of favorable conditions for its multiplication, which leads to the appearance of cancer symptoms.

The sarcoma can also be assessed on the basis of determining the factor that caused the activation of the virus.

What are the symptoms of Kaposi's sarcoma?

There are three stages in Kaposi's sarcoma - the first is the appearance of red-blue and purple spots on the skin, which transform into disc-like infiltrations, which form nodules as the disease progresses.

Similar changes can also appear on the mucous membranes and internal organs, leading to ulceration and, consequently, failure.

The symptoms and course of Kaposi's sarcoma vary independing on the form of the disease.

The classic form of Kaposi's sarcoma , rarely found in our latitude, is characterized by the presence of slowly growing bluish planes on the feet and lower legs, which, as the disease progresses, harden and thicken, forming bumps, which tend to ulcerate and bleed from injury.

Over time, the changes progress to the thighs, torso, arms, and face. They rarely occupy the mucous membranes and internal organs.

Endemic Kaposi's sarcomafound practically only in Central Africa, where it accounts for about 10% of all cancers. Its course is much more aggressive than in the case of other sarcomas. It is characterized by the rapid growth of tumors as well as the involvement of both mucous membranes and internal organs, and even muscles and bones.

The iatrogenic type of Kaposi's sarcomais specific to patients using immunosuppressive drugs after organ transplantation or in the course of autoimmune diseases.

Skin lesions are not limited to the limbs in this type, they can spread over the entire surface of the body. In the iatrogenic type, skin changes regress after discontinuation or change of immunosuppressive treatment.

The HIV-associated epidemic Kaposi's sarcomais the most characteristic skin marker of acquired immunodeficiency (AIDS). This form is characterized by an aggressive course and a typical, at the beginning of the disease, involvement of the facial skin.

The skin lesions are ulcerative. The involvement of the palate mucosa, unheard of in any other form of sarcoma, is particularly alarming. As the disease progresses, involvement of the trunk, limbs, mucous membranes and internal organs, including the heart, is observed.

Suspicion of Kaposi's sarcoma, especially in HIV carriers and patients using immunosuppression, is based on clinical symptoms.

The final diagnosis is made on the basis of the histopathological examination of the biopsy material.

Imaging tests are helpful in the event of suspected internal organ involvement.

Treatment of Kaposi's sarcoma

Treatment of Kaposi's sarcoma is aimed at limiting the progression of the disease, but does not lead to full recovery.

Surgical treatment is used to inhibit the local disease progression, as well as to obtain a satisfactory cosmetic effect.

Kaposi's sarcoma is sensitive to both chemotherapy and radiotherapy, so these treatmentseither individually or simultaneously, taking into account the clinical condition of the patient.

In the case of the HIV-related type, the most important is the rapid implementation or intensification of antiviral treatment. Supportive measures include chemotherapy and radiotherapy.

In the iatrogenic form caused by the use of immunosuppressive drugs, interruption or dose reduction may lead to spontaneous remission of Kaposi's sarcoma.

Radiation therapy is used in patients who cannot discontinue their medications.

Prognosis in Kaposi's sarcoma

Considering all forms of Kaposi's sarcoma, the 5-year survival rate is around 75%.

The prognosis is much better in patients with only the skin involved, but it is significantly worse in the case of the mucous membranes and internal organs.

About the authorBow. Agnieszka MichalakA graduate of the First Faculty of Medicine at the Medical University of Lublin. Currently a doctor during postgraduate internship. In the future, she plans to start a specialization in pediatric hematooncology. She is particularly interested in paediatrics, hematology and oncology.

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Category:

Oncology