Kaposi sarcoma (KS) was first described in 1872 by the Hungarian dermatologist, Moritz Kaposi. From that time until the current human immunodeficiency virus (HIV) disease epidemic identified with the Acquired Immunodeficiency Syndrome (AIDS), KS remained a rare tumor. While most of the cases seen in Europe and North America have occurred in elderly men of Italian or Eastern European Jewish ancestry, the neoplasm also occurs in several other distinct populations: young black African adult males, prepubescent children, renal allograft recipients, and other patients receiving immunosuppressive therapy. The disseminated, fulminant form of KS associated with HIV disease is referred to as epidemic KS to distinguish it from the classic, African, and transplant-related varieties of the neoplasm. In addition, KS has been identified in homosexual men apart from the HIV disease epidemic.
Melanoma is a malignant tumor of melanocytes, which are the cells that make the pigment melanin and are derived from the neural crest. Although most melanomas arise in the skin, they may also arise from mucosal surfaces or at other sites to which neural crest cells migrate, including the uveal tract. Uveal melanomas differ significantly from cutaneous melanoma in incidence, prognostic factors, molecular characteristics, and treatment. (Refer to the PDQ summary on Intraocular (Uveal) Melanoma Treatment...
Although the histopathology of the different types of the Kaposi tumor is essentially identical in all of these groups, the clinical manifestations and course of the disease differ dramatically. A key piece to the puzzle of KS pathogenesis was the 1994 discovery of a gamma herpes virus, human herpes virus type 8 (HHV-8), also known as Kaposi sarcoma herpes virus. HHV-8 was identified in KS tissue biopsies from virtually all patients with classic, African, transplant-related, and AIDS-associated KS but was absent from noninvolved tissue.[4,5,6,7]
Classic Kaposi Sarcoma
Considered a rare disease, classic KS occurs more often in males, with a ratio of approximately 10 to 15 males to 1 female. In North Americans and Europeans, the usual age at onset is between 50 and 70 years. Classic KS tumors usually present with one or more asymptomatic red, purple, or brown patches, plaques, or nodular skin lesions. The disease is often limited to single or multiple lesions usually localized to one or both lower extremities, especially involving the ankles and soles.
Classic KS most commonly runs a relatively benign, indolent course for 10 to 15 years or more, with slow enlargement of the original tumors and the gradual development of additional lesions. Venous stasis and lymphedema of the involved lower extremity are frequent complications. In long-standing cases, systemic lesions can develop along the gastrointestinal tract, in lymph nodes, and in other organs. The visceral lesions are generally asymptomatic and are most often discovered only at autopsy, though clinically, gastrointestinal bleeding can occur. As many as 33% of the patients with classic KS develop a second primary malignancy, which is most often non-Hodgkin lymphoma.[8,9,10]