spitzoid melanoma prognosissubcutaneous melanoma prognosismalignant melanoma stagesmelanoma in situ prognosismalignant melanoma life expectancyspindle cell melanoma prognosismalignant melanoma death ratemalignant melanoma survival rateprognosis metastatic melanomametastasized melanoma prognosismalignant melanoma metastaticmalignant mesothelioma prognosis