Fig. 1.

Comparision of pre- and post-imatinib magnetic resonance imaging (MRI) and tumor tissue in case 1 undergoing neoadjuvant imatinib therapy. (A) MRI before imatinib therapy revealed a 9 × 6.3 cm tumor with a necrotic portion involving the lower rectum. Compression displacement of the left levator muscle and prostatic gland can be seen. (B) MRI after 9 months of neoadjuvant imatinib therapy demonstrates a 6.1 × 3.6 cm residual tumor. (C) Biopsy specimen before neoadjuvant therapy showing spindle-cell tumor cells (H&E, × 200). (D) Immunohistochemical staining for c-kit was positive (c-Kit, × 200). (E) Gross specimen after neoadjuvant imatinib therapy demonstrating an ultralow anterior resection with a yellowish residual tumor mass. (F) Representative section of the tumor mass after imatinib therapy showing a hypocellular myxohyaline stroma (H&E, × 400).