2023 Volume 65 Issue 4 Pages 353-360
A 72-year-old man was diagnosed with prostate cancer 4 years ago and underwent heavy particle and hormone therapies at another hospital. A contrast-enhanced computed tomography (CT) scan, performed because of elevated hepatobiliary enzymes, did not show any abnormalities in the prostate. It did, however, show multiple hepatic masses, a mass shadow in the rectum, and enlarged surrounding lymph nodes. CS revealed a 40 mm submucosal tumor in the rectum with a depression in the apex. The tumor was biopsied and diagnosed as endocrine cell carcinoma. Chemotherapy initiation reduced the tumor size; however, a genomic analysis using a gene panel revealed the presence of prostate cancer-specific fusion gene TMPRSS2-ERG. This report describes a rare case in which neuroendocrine differentiation of prostate cancer was seen after hormone therapy, and the metastatic lesion grew rapidly and invaded the rectum.
