Agree with above.  You all have eagle's eyes and excellent diagnostic skills.

Malignant spindle cell tumor (with a size of 30cm and aytpical mitoses, it is more than atypical, it is malignant).  DDx:  liposarcoma with dedifferentiation (get sections from soft area and look for typical liposarc features.  The pictures shown here may represent dedifferentiation), leomyosarcoma, malignant SFT, MPNST, etc..  We always do a large panel of immunos.