Introduction

Kaposi’s sarcoma (KS) is a type of cancer usually seen on the skin as pink or purple patches. It is also seen in internal organs such as the lungs, digestive tract, and spleen. The skin lesions of KS resemble many other skin diseases; hence, it is important to differentiate them from other diseases. 

After clinical diagnosis, biopsy can confirm the presence of Kaposi’s sarcoma. Various imaging studies further showcase the spread of the cancer in the body. In this article, we will understand various diagnostic tools.

What is Kaposi’s Sarcoma?

Kaposi sarcoma (KS) is a cancer of the skin, mucous membrane of blood vessels, and other internal organs. It is related to Human Herpes Virus (HHV8). This disease can spread to the skin, mucous membrane, lining of the mouth, nose, throat, and lymph nodes. Kaposi’s Sarcoma was first described by a Viennese dermatologist Moritz Kaposi. 

Kaposi sarcoma is different from other types of cancers, as lesions in KS can begin in more than one place simultaneously. Human Herpes Virus (HHV-8) is found in all cases of Kaposi’s sarcoma, but its presence does not confirm the diagnosis of Kaposi’s Sarcoma in all cases. People with a poor immune system are prone to manifest KS.⁷

There are four types of Kaposi Sarcoma variants, which are listed below:

Classic Kaposi Sarcoma

It is more prevalent in men than women. Its onset is between 50 and 70 years of age in North American and European populations. It is associated with red or purple patches on the skin. It involves the lower extremities of the body, like ankles and soles.⁸

Endemic Kaposi Sarcoma

It is the type of KS diagnosed in children and younger adults. The cause of endemic Kaposi's Sarcoma is unclear, but it can occur due to saliva sharing or malnutrition.⁷

AIDS associated Kaposi Sarcoma

Kaposi sarcoma in AIDS patients progresses from a few localized lesions to numerous lesions affecting the skin, oral mucosa, and lymph nodes. The use of anti-retroviral drugs has led to a decline in KS in multiple populations.¹⁰

Iatrogenic Kaposi Sarcoma  

This type of Kaposi Sarcoma is seen in patients who are immunocompromised, mainly due to organ transplant. In the first few months after transplant, symptoms of KS are seen, which get reduced gradually.⁶

Step 1: Clinical Examination

Kaposi Sarcoma is diagnosed based on the type of lesion on the skin; however,  the accurate diagnosis is made after medical tests, as even experienced physicians can misdiagnose based only on clinical appearance.¹

In all forms of KS, lesions first appear as spots on the skin, which can vary from red to purple. The lesions can be flat, slightly raised, or bumpy. These lesions usually appear on the legs and face, but they may involve other organs, like the groin. Sometimes they block fluid passage in the lower body, causing swelling.²

KS can also affect the respiratory system by blocking the passage and causing shortness of breath. The digestive system is also affected from the mouth and throat till anus. These lesions are usually asymptomatic but may bleed and cause obstruction.

In KS, which is AIDS related, lesions are seen in the oral cavity, which may obstruct eating. Oral lesions can be considered the only initial screening sign, as other signs do not ensure early diagnosis, but lesions in the oral cavity are quite significant of the KS.⁴

Different body parts that are affected by KS can include the following:

• Skin
• Lining of the mouth
• Liver
• Spleen
• Lungs and lining of chest, stomach, and intestine³

Step 2: Biopsy – Confirming the Diagnosis 

The diagnosis of Kaposi's Sarcoma can be confirmed only after a procedure called biopsy. A biopsy is a small surgical procedure done to remove a small part of the affected tissue. The removed tissue is studied under a microscope to check for any abnormalities.

The procedure is done under local anesthesia to avoid pain while removing the tissue. In a few cases, antibiotics are given to prevent any infection. 

A few complications that are observed after biopsy include bleeding and bruising, which can be managed easily. If an internal organ is involved in the biopsy, the patient might be asked to stay overnight in the hospital.

There are two types of biopsies:

1. Excisional biopsy: Complete removal of the affected tissue is performed
2. Incisional biopsy: A very small part of the tissue is removed

In Kaposi’s Sarcoma, two other types of biopsies are also performed:

1. Core biopsy: A wide needle is used to remove a small part of the skin
2. Fine-needle aspiration biopsy: A thin needle is used to remove a small part of the skin

If an internal organ like the lungs or digestive tract is involved in the biopsy, the tissue is removed using other procedures like endoscopy.⁵

Imaging Studies – Looking Deeper Inside 

Kaposi sarcoma is usually seen on the skin, but it can be found in internal organs. To find out the spread of KS in internal organs, imaging studies like X-rays, CT scans, and endoscopy are done.

Types of imaging:

Chest X-ray

It is done to find out any abnormality inside the organs and bones around the chest. It is specifically done to examine the lungs and the surrounding area.

Endoscopy 

It is also done to check for any abnormality in the internal organs specifically the gastrointestinal tract. A small tube fitted with light and a lens is inserted into the body via any opening, like the mouth, to look for the digestive tract. In a few cases, an incision is made in the skin to create an opening for the endoscope. An endoscope is also used to remove tissue from internal organs for biopsy.

Bronchoscopy

Bronchoscopy is similar to endoscopy but is done to look for respiratory abnormalities, specifically the lungs and trachea. A small tube fitted with a light and a lens is inserted into the mouth or nose to look for the lungs and windpipe. It is also used to remove the tissue from these organs if a biopsy is required.

After confirmation of Kaposi Sarcoma, other scans are done to find out the spread of cancer through the following tests:

Blood examinations

Blood tests are done to check for any abnormal highs and lows of various factors in the blood. These abnormal highs and lows may be indicative of any disease.

CT scan

A CT Scan or Computed Tomography scan is used to capture images of internal organs from various angles. Sometimes a dye is also inserted into the body to see the images clearly.

PET scan (Positron emission tomography)

It is a nuclear imaging technique where radioactive glucose is injected into a vein. The PET scanner rotates around the body to create an image. A picture is further created that shows the area of higher glucose uptake. It is indicative of higher metabolism and, therefore,  malignancy. The malignant lesions appear brighter than the other parts of the body in the images. These tests check for cancer in the spleen, liver, and lungs.³

Frequently Asked Questions 

What is Kaposi's sarcoma, and what causes it?

Kaposi’s Sarcoma is a cancer caused by the HHV-8 virus and affects the membranes of blood vessels and lymph vessels. It is physically seen as patches on the skin: flat or elevated, and the colour may vary from pink, purple, red to brown.

Who is at risk of getting Kaposi's sarcoma?

People with a weakened immune system are more likely to get Kaposi's sarcoma, especially those affected with HIV/AIDS. The people of Mediterranean and African origin are also at risk of getting KS.

How is Kaposi's Sarcoma diagnosed?

The first step is a physical examination, where the patches on the skin are identified. Biopsy is done in the second step, where a small tissue sample from the affected part is removed and studied. This step confirms KS.

Different scans, like a CT scan and a PET scan, are done to identify the spread of cancer in the body.

Does a skin lesion always mean Kaposi's sarcoma?

No, not every skin lesion is KS. it is only after doing a biopsy and blood examination that we can confirm Kaposi’s sarcoma.

Can Kaposi's sarcoma be treated?

Yes, KS can be treated, but its treatment depends on its spread in the body. There are various treatments like chemotherapy, anti-retroviral drugs, and surgery to treat KS.

Summary

Kaposi’s sarcoma is a malignant cancer usually seen as pink to purple patches on the skin. It also involves the mucosal lining of internal organs like the lungs, digestive tract, liver, and lymph nodes. Diagnosis of KS begins with clinical features like skin lesions, but this cannot be regarded as a reliable marker for its confirmation.

After clinical examination, a biopsy of the affected skin or internal organ is done. The procedure involves the removal of the small or complete tissue from the affected area. This tissue sample is studied under a microscope for various markers that confirm the presence of KS. In case of internal organs, the biopsy is done using specialised tubes which are also fitted with a lens and light. These tubes are inserted into the body through natural openings like the mouth or nose.

After biopsy and a few blood examinations, the presence of human Herpes Virus (HHV-8) is confirmed, which is present in all Kaposi sarcoma cases. There are several scans, like CT scan, PET scan, that help in identifying the spread of infections in the body; thereafter, the treatment is proceeded.

It is essential to identify KS as early as possible, so that the chances of recovery are increased. Contact a healthcare professional if any abnormal symptom is seen in the body.⁹