Participants will have periodic physical examinations and blood tests, including evaluations for responses to treatment. Treatment consistent with accepted standard medical practice will be individualized for each patient. Patients who previously participated in a NIH study will be followed for possible long-term benefits or side effects of treatment. Patients treated with alpha-interferon or interleukin-2 (IL-2) may continue treatment with that medication if it is felt that they might benefit from it. Blood samples may be drawn as part of standard medical care and for research purposes. Other tests may be done as appropriate for diagnosis and treatment, including, for example, a chest X-ray, electrocardiogram, or tissue biopsy. Patients will be seen for follow-up visits at regular intervals to monitor treatment progress.