Linitis plastica of the rectum secondary to metastatic prostate cancer: A case report of a rare presentation and literature review

Linitis plastica is a rare tumor with poor prognosis. It is a circumferentially infiltrating intramural tumor which can result in rigid, nondistensible thickening of the affected organ. It most commonly affects the stomach, followed by the rectum, and can be due to primary or secondary cancer. Secondary rectal linitis plastica (RLP) caused by metastatic cancers has been reported from the stomach, breast, gallbladder, urinary bladder, and very rarely, the prostate, with only <5 reported cases in the literature. We report the case of a 66-year-old man who presented with altered bowel habit and loss of weight, with elevated prostate-specific antigen of 180.6 ng/mL. Sigmoidoscopy showed thickened rectal mucosa, and biopsy was negative for malignancy. Magnetic resonance imaging showed circumferential wall thickening, “target sign” appearance suggestive of RLP, PIRADS 5 lesion with extraprostatic extension, infiltrating bilateral seminal vesicles, and right neurovascular bundle. Repeat colonoscopy was performed under anesthesia, and deeper biopsy revealed poorly differentiated metastatic prostate adenocarcinoma. This case report highlights the atypical presentation of metastatic prostate cancer secondary to RLP, the rarity of this condition, and emphasizes the importance of deeper biopsy in RLP due to disease involvement predominantly in the submucosa and muscularis propria layers.