Transrectal Ultrasound MRI-Fusion Biopsy of Perirectal Mass

This case report describes the novel use of ultrasound-guided MRI-fusion biopsy to sample an extraluminal perirectal mass. This is a 64-year-old man with a history of pT3N2b mucinous adenocarcinoma of the right colon with metastatic disease to the mesocolic lymph nodes. Two years after initial resection he was found on restaging CT to have a mass measuring ∼4.0 × 4.8 cm superior to the seminal vesicles. Fluorodeoxyglucose (FDG)-positron emission tomography (PET) showed a moderately FDG avid soft tissue mass interposed between the prostate and the rectum. Multiparametric MRI revealed a 6.2 × 4.6 × 2.8 cm heterogeneous lobulated T2 hyperintense mass with enhancement just superior to the seminal vesicles. This mass was unable to be viewed using sigmoidoscopy. Using UroNAV technology, we were able to biopsy the mass in the clinic setting. Biopsy was confirmed as recurrent mucinous adenocarcinoma.