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What is Kaposi's sarcoma (KS) usually occurs when CD4+ lymphocyte counts are: and explain in detail?
When CD4 count falls less than 200/L, the patient develops full-blown AIDS. This stage is characterized by the development of HIV wasting syndrome with weight loss and diarrhea for 1 month.
The patients with AIDS show a marked susceptibility to the development of malignancies. 
Human herpes virus-8–associated Kaposi’s sarcoma is the most noted malignancy associated with AIDS.

​Parija SC. Textbook of Microbiology & Immunology. Elsevier Health Sciences; 2014. Page:571