Objective: Well-differentiated liposarcoma (WDLS) can undergo dedifferentiation to nonlipogenic sarcomas. Solitary fibrous tumour (SFT) characteristics have not been highlighted as a pattern of dedifferentiated liposarcoma (DLS). However, this does occur and could be the cause of diagnostic pitfalls in atypical locations or partial tumoral resections. The aim of this comparative study is to demonstrate that some DLS's may show morphologic features resembling SFT's, and furthermore to describe the clue features supporting differential diagnosis. Method: Study comprised 11 WDLS-DLS and 12 SFT (4 malignant). Histological features were systematically reviewed, and CD34/CD99/S100/BCL2 immunostains and MDM2 FISH-analysis were evaluated in all cases. Results: There are many overlapping characteristics between DLS and SFT (Table 1 ). Significant differences between both tumor types were observed in lipoblast-like cells (lpc); mature adipocitic cells within tumor (mac); stromal bands surrounding adipose tissue with atypical cells (sac); patternless (pa); keloidal-collagen (kcm) and haemangiopericytoid-pattern (hp). Diagnostic accuracy of different features is shown in table 2.