microscopic colitis collagenous colitis https://rarediseases.info.nih.gov/diseases/6135/collagenous-colitis https://www.malacards.org/card/collagenous_colitis MONDO:0000703 MESH:D046729 DOID:0060183 MedDRA:10048928 ICD9:558.9 SCTID:19311003 UMLS:C0238067 A type of microscopic colitis of unknown etiology. It is characterized by the presence of collagen deposits in the lamina propria of the colonic mucosa. Patients present with chronic watery diarrhea. Colonoscopy reveals normal-appearing mucosa. The diagnosis is made with the microscopic examination of the colonic biopsy samples. MEDGEN:65945 EFO:1001293 NCIT:C27021 icd11.foundation:1322041450 Orphanet:36205 ICD10CM:K52.831