LAUSR

Linitis plastica is a rare condition showing circumferentially infiltrating intramural anaplastic carcinoma in a hollow viscus, resulting in a tissue thickening of the involved organ as constricted, inelastic, and rigid. While most secondary rectal linitis plastica (RLP) is caused by metastasis from stomach, breast, gallbladder, or bladder cancer, we report an extremely rare and unique case of secondary RLP due to prostate cancer with computed tomography (CT) and magnetic resonance imaging (MRI) findings, including diffusion weighted imaging (DWI). A 78-year-old man presented with approximately a 2-mo history of constipation and without cancer history. On sigmoidoscopy, there was a luminal narrowing and thickening of rectum with mucosa being grossly normal in its appearance. On contrast-enhanced CT, marked contrast enhancement with wall thickening of rectum was noted. On pelvic MRI, rectal wall thickening showed a target sign on both T2-weighted imaging and DWI. A diffuse infiltrative lesion was suspected in the prostate gland based on low signal intensity on T2-weighted imaging and restricted diffusion. A transanal full-thickness excisional biopsy revealed metastasis from a prostate adenocarcinoma invading the submucosa to the muscularis propria consistent with metastatic RLP. We would like to emphasize the CT and MRI findings of metastatic RLP due to prostate cancer.