Histology Course A IV 18 Department of Pathology, University of Zurich Histokurs

A IV 18 Crohn's disease of ileum HE further information (German) on HiPaKu 
  ICD-10: K50.0
35-year-old female suffered from cramping abdominal pain, diarrhoea and flatulence since about 2 years. Her erythrocyte sedimentation rate was increased. (Specimen from surgical resection).
- Mucosa demonstrates multiple ulcers, some of which deeply penetrate the mucosa in a slit-like fashion.
- In between ulcers, the mucosa is oedematous; some of the villi are flattened and broad.
- The lamina propria exhibits an increased inflammatory infiltrate consisting mainly of lymphocytes and plasma cells. The inflammatory infiltrate extends into the submucosa, with formation of lymphoid aggregates. The latter can also be seen in the subserosa (transmural inflammation).
- The submucosa exhibits considerable fibrosis.

The transmural inflammation with formation of lymphoid aggregates, the fibrosis of the submucosa and occasional granulomas are hallmarks of Crohn's disease. Granulomas are observed in 50-70% of cases. They are poorly formed and consist of loose aggregates of epitheloid cells with occasional Langhans giant cells. Granulomas are missing in this biopsy specimen.