Atypical Lipomatous Tumor / Well-differentiated Liposarcoma

Comments:
The patient was a 70 y/o male who presented with a large ALT/WDL in the retroperitoneum. Four years after resection, he presented with a 9.0 cm recurrence. It had a variegated appearance consisting of firm grey-white areas, gelatinous foci, hemorrhage, and unremarkable yellow adipose tissue. High power view from that tumor shows atypical stromal cells with sharply outlined nuclear pseudoinclusions.