Fulminant colitis in inflammatory bowel disease - Detailed pathologic and clinical analysis

PURPOSE: The morphologic features of fulminant colitis may be nonspecific, making differentiation between ulcerative colitis and Crohn's disease diffi cult, even after colectomy. The aims of this study were 1) to identify hist ologic features that accurately differentiated ulcerative colitis, Crohn's disease, and indeterminate colitis in fulminant colectomy specimens; 2) to determine how frequently subsequent clinical course altered the pathologic diagnosis; and 3) to evaluate the natural history of histologically diagnos ed indeterminate colitis. METHODS: Ninety-five fulminant colectomy specimen s were evaluated, of which 85 had an original diagnosis of fulminant inflam matory bowel disease. Complete pathologic material and comprehensive clinic al follow-up information was available on 67 cases of inflammatory bowel di sease. These were re-evaluated in a blinded fashion, and histopathologic fe atures were compared with the original diagnosis and reviewed in the light of subsequent clinical behavior to reach a final diagnosis. RESULTS: Evalua tion of macroscopic features was not helpful in differentiating ulcerative colitis from Crohn's disease. Microscopic examination correctly diagnosed u lcerative colitis or Crohn's disease in only 58 of 67 (87 percent) cases. A further three cases (4 percent) were definitively classified after correla tion with clinical data, leaving a residual six cases that were diagnosed a s indeterminate colitis. Granulomas and lymphoid aggregates were the two mo st specific indicators of Crohn's disease. CONCLUSIONS: Histopathologic eva luation alone has limitations in the accurate classification of Fulminant i nflammatory bowel disease. Histologically diagnosed indeterminate colitis i s a heterogeneous group that may include some patients who subsequently pro ve to have ulcerative colitis or Crohn's disease.