spindle cell tumorspindle cell neoplasm treatmentmalignant spindle cell tumoratypical spindle cell tumorbenign spindle cell tumormalignant spindle cell neoplasmspindle cell neoplasm sarcomamyxoid spindle cell tumorcellular spindle cell neoplasmatypical spindle cell neoplasmpleomorphic spindle cell neoplasmbenign spindle cell neoplasm