Kaposi Sarcoma: what it is and why it matters

Kaposi sarcoma (KS) is a type of cancer that often shows up as purple, red, or brown patches on the skin or in the mouth. It can also affect the lungs, digestive tract, and lymph nodes. The cancer is linked to a virus called human herpesvirus‑8 (HHV‑8). Not everyone with HHV‑8 will get KS — it usually appears when the immune system is weak.

What causes Kaposi sarcoma and who gets it?

HHV‑8 is the main driver. KS appears more often in people with HIV who aren’t on effective antiretroviral therapy, in people taking strong medicines that suppress the immune system (like after an organ transplant), and in certain regions where HHV‑8 is more common. There are several types: classic (slow, older adults), epidemic/HIV‑related (faster, linked to HIV), endemic (seen in parts of Africa), and iatrogenic (caused by medical immunosuppression).

Symptoms, diagnosis, and what to expect

Do you have painless purple spots that don’t go away? That’s the most common sign. KS lesions can be flat or raised and may bleed or ulcerate. If the lungs or gut are involved, people may cough, breathe poorly, or have abdominal pain and bleeding.

Diagnosis usually starts with a skin exam and a biopsy — a small sample sent to a lab. The pathologist looks for the typical spindle cells and blood vessel growth. Doctors may also test for HHV‑8, check HIV status, and use imaging (chest CT, endoscopy) when internal organs might be affected.

Treatment depends on how widespread the disease is and what’s causing the weak immune system. For HIV‑related KS, getting and staying on antiretroviral therapy often improves lesions and can be enough for mild disease. When lesions are more severe or internal, options include systemic chemotherapy (liposomal doxorubicin or paclitaxel are common), interferon in select patients, and targeted local therapy like surgery, cryotherapy, or radiation for troublesome spots.

Transplant patients may need their immunosuppressive drugs adjusted under close medical supervision. Supportive care matters: manage wounds, control infections, and treat lymphedema (swelling) if present. Clinical trials are an option for people who don’t respond to standard care.

When should you see a doctor? If a new purple or red skin lesion appears, if existing lesions grow quickly, if you have unexplained cough, blood in stool, swelling of a limb, or weight loss — get evaluated. Early diagnosis and treating any underlying immune problem make a real difference.

KS can be managed in many cases. The key steps: test for HIV and HHV‑8 when suspected, biopsy suspicious lesions, and tailor treatment to how aggressive the disease is and what’s weakening the immune system. Talk openly with your doctor about options and follow‑up plans so you know what to expect.