Dedifferentiated liposarcoma with extensive cystic change causing significant diagnostic challenges: report of two cases and review of the literature

Fig. 1. Radiologic findings and macroscopic images of case 1: A Ultrasound image depicting a well-defined lesion with a hyperechoic internal structure. B Coronal CT image showing a cystic lesion (arrowhead) below the liver. C Axial, and D coronal T1-weighted contrast-enhanced MRI images of the lesion (arrowhead) with close proximity to the kidney (arrow). E Photograph of the fresh nephrectomy specimen with the adherent mass F Photograph of the opened specimen after formalin fixation showing a large cystic space with red deposits and an irregular wall

Fig. 2. Histology (A-H) and ancillary studies (I-K) of case 1: A Scanning magnification of the tumor showing an abrupt transition between the well-differentiated liposarcoma component (bottom right) and the dedifferentiated liposarcoma component (top left). B, C Higher magnification of the dedifferentiated component with areas of higher cellularity (B) and lower cellularity with stromal hyalinization and interspersed pleomorphic tumor cells (C). D Higher magnification of the well-differentiated liposarcoma component showing adipocytes of varying size, atypical hyperchromatic stromal cells (asterisk) and occasional lipoblasts (arrowhead). E Scanning magnification of the wall of the cystic space showing a prominent nodularity (arrowheads) with formation of smaller pseudocysts (asterisk). F Higher magnification of the inner aspect of the pseudocystic space showing adherent blood and hemosiderin (asterisk), fibrin, stromal sclerosis and pleomorphic tumor cells (arrowhead). G, H Higher magnification of the tumor nodules showing relatively bland spindled cells with prominent whirling (G) and highly cellular areas with oval to round tumor cells (H). I, J Immunohistochemical stainings showing…

Fig. 3. Radiologic findings and macroscopic images of case 2: A Axial contrast-enhanced CT and B T1-weighted MRI images showing a cystic lesion (arrow head) with calcifications of the cyst wall adjacent to the right kidney (arrow). C Coronal T2-weighted MRI image depicting the lesion (arrowhead) below the liver (asterisk). D Photograph of the bisected nephrectomy specimen (arrow) with the adherent cystically configured tumor exhibiting an irregularly thickened, partially bone-hard wall structure (arrow heads)

Fig. 4. Histology (A-E) and ancillary studies (F–H) of case 2: A Scanning magnification of the wall showing irregular ossifications and calcifications and a variation of cellularity. B Periphery of the tumor with sparse intratumoral adipocytes (arrowheads) and adjacent regional adipose tissue (asterisk). C, D Higher magnification of A showing (C) areas of high cellularity with foci of cartilaginous differentiation (arrowheads) and osteoclast-like giant cells (asterisk) and (D) areas of lower cellularity with relatively bland small tumor cells in a myxoid and collagen-rich stroma. E Area of heterologous osteosarcomatous differentiation with markedly atypical tumor cells producing osteoid and SATB2 expression by immunohistochemistry (inset). F, G Immunohistochemical stainings showing strong nuclear positivity for mdm2 (F) and cdk4 (G). H MDM2 / CEN12 FISH showing uncountable green signals (MDM2) and increased red signals (CEN12)