A case of rapid growing rectal cancer for the duration of taking Calcium Polystyrene Sulfonate

Abstract

An asymptomatic 80-years-old woman with an angiosarcoma of upper arm was incidentally found on PET to have a hot spot in the lower abdomen. She had been prescribed Calcium Polystyrene Sulfonate (CPS) .
Colonoscopy revealed polypoid lesion about 30 mm in size in recto sigmoid, which endoscopic diagnosis was submucosal invasive carcinoma, biopsy specimen shows moderately differentiated adenocarcinoma. A year later, she complained bloody stool and lower abdominal pain. Second colonoscopy showed a white coated large polypoid lesion occupying a rectal lumen.
Anterior resection was performed, and resected specimen showed 80×50 mm tumor with deep ulcer, pathological finding shows poorly differentiated with moderately differentiated component penetrating to right ovary, lymph node metastasis was positive for cancer. Many CPS crystals were deposited in the ulcer bed. CPS is known as mucosal toxic agents. Our case suggested CPS might be the cause of ulceration and rapid progression of the tumor.