Spermatic granuloma complicating abdominoperineal resection of the rectum: diagnosis by CT, MR imaging, and percutaneous biopsy

A 60-year-old man underwent abdominoperineal resection of the rectum for moderately wall-differentiated adenocarcinoma. The pencolic lymph nodes were free of tumor, but numerous metastatic nodules were noted in the liver at the time of surgery. The patient did not receive radiation therapy. Four months after surgery, a CT scan showed a presacral mass near the surgical site in the pelvis (Fig. 1). On MR imaging, the mass had a high signal intensity on the T2weighted image (Fig. 2), suggesting that the lesion was recurrent tumor or inflammation rather than postoperative fibrosis. A CT-guided percutaneous biopsy was performed with an 18-gauge needle by using a transgluteal approach. Pathologic examination of the spedmen was diagnostic for a spermatic granuloma; it showed innumerable sperm, many of which had been engulfed by reactive histiocytes.