Overview

Kaposi sarcoma (KS) is an angioproliferative cancer that occurs in the immunosuppressed, mostly those with HIV/AIDs. It mostly affects mucocutaneous sites, especially the skin and in some cases the oropharynx. Visceral and other extra-cutaneous involvement has been described.

The most common extracutaneous site of Kaposi sarcoma is the gastrointestinal tract, hence the name gastrointestinal Kaposi sarcoma (GI-KS). About 75% of affected patients are asymptomatic. Gastrointestinal Kaposi sarcoma most often occurs in the presence of cutaneous lesions, and rarely occurs in the absence of cutaneous lesions. People who are symptomatic usually present with vague abdominal discomfort, abdominal cramps, nausea, vomiting, diarrhoea, and sometimes upper and lower gastrointestinal bleeding.¹

Clinical Presentation/ Symptoms of Gastrointestinal Kaposi Sarcoma

• Cutaneous lesions: present as multiple, pigmented, raised or flat, painless lesions that do not blanch, that is, they do not lose colour when pressure is applied to them. Kaposi sarcoma is a low-grade vascular tumour associated with human herpesvirus 8 (HHV-8). The first skin changes are usually harmless and don’t cause any symptoms. They look like small, flat or slightly raised spots that can be pale pink, bright purple, or other shades in between. Sometimes, the skin spots grow into lumps that stick out, may have open sores, and can bleed. These lumps can also cause painful swelling in the area. Kaposi sarcoma is accurately diagnosed with the help of histology²
• Gastrointestinal hemorrhage: bleeding has been reported to occur in the oral cavity, esophagus, stomach and large bowels. Gastrointestinal bleeding can present as bloody diarrhoea if it is from the intestines, or vomiting of blood if it is from the esophagus or oral cavity³
• Abdominal discomfort: This may occur in the presence or absence of nausea and vomiting. When the bowel is auscultated, a hyperactive bowel sound is heard. Nausea and vomiting, when present, can occur for weeks. They can also have abdominal cramps
• Diarrhoea: The diarrhoea can be mucoid in onset. When there is bowel perforation, the diarrhoea can become bloody

Diagnostic Challenges of Gastrointestinal Kaposi Sarcoma

So many opportunistic infections can present with nausea, vomiting, abdominal pain, bloody and non-bloody diarrhoea, therefore making the diagnosis of gastrointestinal Kaposi sarcoma difficult to confirm clinically. Those with Kaposi sarcoma skin lesions and GI-KS are easily diagnosed as compared to people without kaposi sarcoma skin lesions.¹

Some of the opportunistic infections that present with similar symptoms as gastrointestinal Kaposi sarcoma include:

• Cytomegalovirus infection: This is an opportunistic infection that occurs in the immunocompromised such as individuals with HIV/AIDs individuals who have undergone organ transplant. This virus presents with gastrointestinal symptoms such as diarrhoea and abdominal pain. They also have non-gastrointestinal symptoms such as headache, weight loss, malaise, respiratory symptoms, lymphadenopathy, jaundice, and joint pain⁴
• Cryptosporidiosis: This is an infection caused by the parasite cryptosporidium. It presents with abdominal pain, vomiting and watery diarrhoea. In some instances, they can present with a cough
• Giardiasis: This is an infection caused by a protozoan known as giardia lamblia. It presents with bloating, abdominal cramps, nausea, vomiting, weight loss, diarrhoea, and greasy stools
• Mycobacterium avium-intracellulare: They present with a series of symptoms which include chest pain, wheezing, cough, abdominal pain, diarrhoea, fatigue, weight loss and lymphadenopathy

How to Diagnose Gastrointestinal Kaposi Sarcoma?

Finding and treating Gastrointestinal Kaposi sarcoma early is important for staying healthy. Doctors usually diagnose it by looking inside the digestive system using an endoscopy and taking a small tissue sample biopsy to test for the tumour.

According to the guidelines for prevention and treatment of opportunistic infections in HIV-infected adults and adolescents presenting with diarrhea, endoscopic evaluation

is only indicated when medical tests for infectious causes (stool culture, microscopy,

Clostridium difficile toxin assay, and blood culture) fail to reveal an etiology or treatment for an established diagnosis fails.¹

Sometimes, these test results take a long time to come back, which can delay finding out if someone has KS inside their intestines, and this can affect how well the treatment works. It is also possible for someone with HIV/AIDS to have both KS in the colon and an infection causing diarrhea at the same time. But when doctors find an infection, they may stop looking for other causes, like KS, which could lead to missing the full diagnosis.

Clinical factors that predict an endoscopic diagnosis of GI-KS in the absence of skin lesions. Men who have sex with men, low CD4 count (< 100 cells/ml), high HIV viral load, and no HAART treatment for HIV/AIDs cases are strong predictors of GI-KS. In some instances, people with HIV with higher CD4 counts have demonstrated gastrointestinal Kaposi sarcoma.

Due to the presence of the overlapping features with opportunistic gastrointestinal infections and absence of cutaneous lesions of KS in some cases, it is important to include early endoscopic evaluation with biopsy in the primary diagnostic workup of diarrhoea and other nonspecific abdominal symptoms in the immunocompromised patients, such as people with HIV/AIDs 

Summary

Gastrointestinal Kaposi Sarcoma is a serious condition that mostly affects people with weakened immune systems, especially those with HIV/AIDS. It can be difficult to diagnose because its symptoms, such as abdominal pain, diarrhoea, and intestinal bleeding, are similar to many common infections in these populations. While GI-KS is easier to detect when skin lesions are present, it can still occur without them. Because delays in diagnosis can affect treatment and outcome, it is important that doctors consider early endoscopy and biopsy in individuals with HIV with unexplained digestive symptoms. Recognizing the possibility of GI-KS early can lead to better care and improved survival.