In 2014, a case of parasite-to-host cancer transmission occurred in a 41-year-old man in Colombia with a compromised immune system due to HIV. The man's tumor cells were shown to have originated from the dwarf tapeworm, "Hymenolepis nana". In 1990s, an undifferentiated pleomorphic sarcoma was transmitted from a patient to a surgeon when he injured his hand during an operation – within five months a tumor developed on the hand. The tumor was removed. In 1986, a laboratory worker accidentally bruised herself with the needles she was using to inject colonic cancer cells into mice. She developed a small tumor on her hand in two weeks.