Patient description: A 25-year-old woman presents to the clinic complaining of prolonged fatigue. She denies difficulty sleeping and sleeps an average of 8 hours a night. She also notes hair loss, a change in her voice and weight gain during the previous 6 months. She complains of cold intolerance. On examination she has a prominent, soft, uniform anterior cervical mass at the midline.

Clinical trial eligibility criteria: eligible ages (years): 18.0-999.0,  Recurrent Melanoma Stage IV Skin Melanoma Patients must have histologically confirmed melanoma with evidence of metastatic disease either by radiologic or physical examination In-transit metastases are allowed Biopsy should be performed to reconfirm the diagnosis in cases of doubt Patients must have measurable disease For computed tomography (CT) imaging, this is defined as at least one lesion that can be accurately measured in at least one dimension (longest diameter to be recorded) as ≥ 20 mm by conventional techniques or as ≥ 10 mm by spiral CT scan For cutaneous lesions, these must be measurable with a ruler and documented photographically with a ruler in place There are no limits on the number of prior therapies; patients must not have received a vaccine containing any of the melanoma antigen peptides, nor previously received daclizumab; at least 4 weeks must have passed since prior chemotherapy or radiation therapy (6 weeks for BCNU [carmustine] or mitomycin C) Life expectancy greater than or equal to 12 weeks Eastern Cooperative Oncology Group (ECOG) performance status 0-1 (Karnofsky ≥ 80%) Leukocytes ≥ 3,000/mcL  Patients who have had chemotherapy, biological or radiotherapy within 4 weeks (6 weeks for nitrosoureas or mitomycin C) prior to entering the study or those who have not recovered from adverse events due to agents administered more than 4 weeks earlier Patients may not be receiving any other investigational agents Presence of untreated brain metastases; all patients must undergo brain imaging as part of the pre-study evaluation; only patients with no brain metastases, or with brain lesions successfully treated by stereotactic radiation or surgical removal without progression at 28-day follow-up and off corticosteroids for 4 weeks, will be eligible History of allergic reactions attributed to compounds of similar chemical or biologic composition IL-12 or other agents used in the study Concurrent systemic corticosteroids (except physiologic replacement doses) or other immunosuppressive drugs (eg. cyclosporin A) Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, significant cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements Pregnant women are excluded from this study; breastfeeding should be discontinued if the mother is treated with IL-12; women of child-bearing age must be tested for urinary or serum beta-human chorionic gonadotropin (HCG) Patients with intrinsic immunosuppression, including seropositivity for human immunodeficiency virus (HIV) antibody; patients should be tested for HIV; HIV-positive patients are ineligible Psychiatric illness that may make compliance to the clinical protocol unmanageable or may compromise the ability of the patient to give informed consent; patients with clinical evidence of dementia should have a competent designee participate in decision making Serious concurrent infection, including active tuberculosis, hepatitis B, or hepatitis C; patients should be tested for hepatitis B surface antigen and hepatitis C antibody; patients who are hepatitis C antibody (Ab) positive can be eligible if they are polymerase chain reaction (PCR)-negative