RB1 and spindle cell lipoma: In 2010, Mentzel et al. postulated that SCLPS could possibly represent the atypical counterpart of spindle cell lipoma (SCL) on the basis of clinicopathological and molecular features, including RB transcriptional corepressor 1 (RB1) gene deletion and lack of MDM2 proto-oncogene (MDM2) amplification [3].