This 37-year-old previously healthy female presents with a three month history of bloody diarrhea. She reports that during the same time, she has been experiencing abdominal cramping, tenesmus, and 20 lbs of weight loss. During her colonoscopy, the mucosa appears irregular (figure 1) extending from the rectum to the splenic flexure, with normal appearing more proximally (figure 2), and an unremarkable terminal ileum. What is the likely diagnosis, and Mayo endoscopic score for the mucosa in each of these images?

• MES 0: Normal or inactive disease (D–F) 
• MES 1: Mild disease, with erythema (D), decreased vascular patterns (E), and mild erosion (F)
• MES 2: Absence of vascular patterns, and erosions. (G-I) 
• MES 3: (J-K) serious ulceration, and spontaneous bleeding (L)

In this patients case, the first image demonstrates deep ulceration (MES 3), while the second demonstrates healthy mucosa with regular vascular patterns (MES 0):

Source: Xu W, Liu F, Tang W, Gu Y, Zhong J, Cui L, Du P. The Mayo Endoscopic Score Is a Novel Predictive Indicator for Malignant Transformation in Ulcerative Colitis: A Long-Term Follow-Up Multicenter Study. Front Surg. 2022 Mar 16;9:832219. doi: 10.3389/fsurg.2022.832219. PMID: 35372478; PMCID: PMC8965860. Available from https://www.frontiersin.org/articles/10.3389/fsurg.2022.832219/full

Gajendran M, Loganathan P, Jimenez G, Catinella AP, Ng N, Umapathy C, Ziade N, Hashash JG. A comprehensive review and update on ulcerative colitis. Dis Mon. 2019 Dec;65(12):100851. doi: 10.1016/j.disamonth.2019.02.004. Epub 2019 Mar 2. PMID: 30837080. Available from https://pubmed.ncbi.nlm.nih.gov/30837080/

The patient was started on appropriate medical therapy, and one week later the biopsy results returned revealing moderate to severe colitis: