Purpose To compare the apparent diffusion coefficients (ADCs) of myxoid and nonmyxoid soft‐tissue tumors using line‐scan diffusion‐weighted imaging (LSDWI), and to investigate the myxoid matrix influence on ADCs of soft‐tissue tumors. Materials and Methods This study enrolled 44 patients with soft tissue tumors. They were divided into two groups: one with myxoid‐containing soft‐tissue tumors (N = 23) and the other with nonmyxoid soft‐tissue tumors (N = 21). The 44 patients were also classified histologically into 26 with malignant soft‐tissue tumors and 18 with benign soft‐tissue tumors. LSDWI was performed using b values of 5 and 1000 second/mm2. The ADCs of the tumors were calculated and compared for myxoid and nonmyxoid tumors and for benign and malignant tumors. Results The ADC (mean ± SD) was 1.92 ± 0.41 × 10–3 mm2/second in myxoid containing tumors, whereas the ADC was 0.97 ± 0.33 × 10–3 mm2/second in nonmyxoid tumors. The ADCs of the myxoid and nonmyxoid tumors were significantly different (P < 0.01). The ADCs were 1.45 ± 0.59 × 10–3 mm2/second in malignant tumors and 1.50 ± 0.64 × 10–3 mm2/second in benign tumors. The ADCs of benign and malignant soft‐tissue tumors were not significantly different. Conclusion The ADCs of myxoid‐containing soft‐tissue tumors were significantly higher than those of nonmyxoid soft‐tissue tumors. The myxoid matrix influences ADCs of both benign and malignant soft‐tissue tumors. J. Magn. Reson. Imaging 2007;25:1199–1204. © 2007 Wiley‐Liss, Inc.

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Congenital

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A case of malignant phyllodes tumor of the prostate in a 67-year-old man is reported. The patient was referred to a hospital for urinary retention. From material taken at three transurethral resections of the prostate (TURP), a histological diagnosis of benign prostatic hyperplasia was made. However, at the fourth TURP, phyllodes tumor was diagnosed due to the presence of elongated epithelial ducts and proliferating cellular stroma with mitosis and nuclear atypia. Two months later, total cystoprostatectomy was performed. Histologically, the tumor was composed of dysplastic stromal cells and irregularly elongated epithelial ducts. Five months later the patient developed multiple lung and pelvic lymph node metastases and died. This report documents progression to a higher histological grade of prostatic phyllodes tumor documented with sequential pathological findings obtained from four TURP and surgical specimens over about 3 years.