Diagnosis
Although KS may be suspected from the appearance of lesions and the patients risk factors, a definite diagnosis can be made only by biopsy and microscopic examination. Detection of the KSHV protein LANA in tumor cells confirms the diagnosis.In differential diagnosis, arteriovenous malformations, pyogenic granuloma and other vascular proliferations can be microscopically confused with KS. Differential diagnosis of Kaposis sarcoma
Source:
Naevus
Histiocytoma
Cryptococcosis
Histoplasmosis
Leishmaniasis
Pneumocystis lesions
Dermatophytosis
Angioma
Bacillary angiomatosis
Pyogenic granuloma
Melanoma

Classification
HHV-8 is responsible for all varieties of KS. Since Moritz Kaposi first described the cancer, the disease has been reported in five separate clinical settings, with different presentations, epidemiology, and prognoses. : 599  All of the forms are infected with KSHV and are different manifestations of the same disease but have differences in clinical aggressiveness, prognosis, and treatment. Classic Kaposi sarcoma most commonly appears early on the toes and soles as reddish, violaceous, or bluish-black macules and patches that spread and coalesce to form nodules or plaques. : 599  A small percentage of these patients may have visceral lesions. In most cases the treatment involves surgical removal of the lesion. The condition tends to be indolent and chronic, affecting elderly men from the Mediterranean region, Arab countries, or of Eastern European descent. Israeli Jews have a higher rate of KSHV/HHV-8 infection than European peoples. Endemic KS, which has two types. Although this may be present worldwide, it has been originally described later in young African peoples, mainly those from sub-Saharan Africa.
Kaposis sarcoma (KS) is a type of cancer that can form masses in the skin, in lymph nodes, in the mouth, or in other organs. The skin lesions are usually painless, purple and may be flat or raised. Lesions can occur singly, multiply in a limited area, or may be widespread. Depending on the sub-type of disease and level of immune suppression, KS may worsen either gradually or quickly. KS is caused by a combination of immune suppression (such as due to HIV/AIDS) and infection by Human herpesvirus 8 (HHV8 – also called KS-associated herpesvirus (KSHV)).Four sub-types are described: classic, endemic, immunosuppression therapy-related (also called iatrogenic), and epidemic (also called AIDS-related). Classic KS tends to affect older men in regions where KSHV is highly prevalent (Mediterranean, Eastern Europe, Middle East), is usually slow-growing, and most often affects only the legs. Endemic KS is most common in Sub-Saharan Africa and is more aggressive in children, while older adults present similarly to classic KS. Immunosuppression therapy-related KS generally occurs in people following organ transplantation and mostly affects the skin. Epidemic KS occurs in people with AIDS and many parts of the body can be affected. KS is diagnosed by tissue biopsy, while the extent of disease may be determined by medical imaging.Treatment is based on the sub-type, whether the condition is localized or widespread, and the persons immune function. Localized skin lesions may be treated by surgery, injections of chemotherapy into the lesion, or radiation therapy. Widespread disease may be treated with chemotherapy or biologic therapy.