Medical process--use of dichlorodifluoromethane (CCl.sub.2 F2) and chlorodifluoromethane (CHClF.sub.2) as cryogens for treating skin lesions

A method of cryogenically treating a skin lesion comprising the steps of:

• (a) placing a hollow fluid retaining device having a side wall defining a bottom open end of a size slightly greater than a skin lesion to be removed by cryosurgery and a top open end in an upright position in which said bottom open end seals against a patient's skin entirely surrounding said skin lesion and said top open end is above said bottom open end,
• (b) introducing into said top open end of said upright fluid retaining device from a container separate from said fluid retaining device a liquid cryogenic agent selected from the group consisting of chlorodifluoromethane and dichlorodifluoromethane to cause a liquid pool of said cryogenic agent to contact directly the entire area of said skin lesion for a period of time to permit said cryogenic agent to reduce the temperature of said skin lesion to a temperature no higher than -30.degree. C.,
• (c) terminating said introducing step,
• (d) retaining said hollow fluid retaining device in said upright position surrounding said skin lesion after said introducing step has been terminated in order to accumulate and retain said liquid cryogenic agent within said bottom open end of said fluid retaining device and in contact with said skin lesion in order to maintain said skin lesion at said reduced temperature while said cryogenic agent is evaporating, and
• (e) subsequently removing said fluid retaining device from said upright position after said liquid cryogenic agent has evaporated.