Undifferentiated pleomorphic sarcoma usually large, unencapsulated with grey firm heterogenous cut surface. It has no distinctive macroscopic features except that it has frequent necrosis and haemorrhage.

The tumour cells arranged in storiform pattern, irregular fascicles, with variable cellularity. The cells are pleomorphic and bizarre with foamy cytoplasm and marked atypia, in background of inflamed collagenous stroma.

Undifferentiated pleomorphic sarcoma