RESUMEN
Ulcerative colitis (UC) is a chronic inflammatory disorder of the gastrointestinal tract that affects the large bowel. Its etiology remains controversial. However, an infectious or immunologic origin is considered the primary cause. The onset of UC is typically slow and insidious, but some patients may present acutely with symptoms mimicking infectious colitis. We report a case of ulcerative colitis mimicking acute hemorrhagic colitis at initial presentation. A 60-year-old man was referred to Yeungnam University Hospital for bloody diarrhea and abdominal pain. Sigmoidoscopy revealed mildly edematous mucosa in the rectum and hyperemic mucosa with petechiae in the sigmoid colon. The patient was treated with antibiotics for several days, and his symptoms improved. However, after one month, his bloody diarrhea relapsed. Follow-up sigmoidoscopy revealed mucosal friability in the rectum and sigmoid colon. He was diagnosed with ulcerative colitis, and his symptoms were improved with mesalazine and a steroid enema.