Histology Course S I 17 Department of Pathology, University of Zurich Histokurs

S I 17 cloacogenic anal carcinoma HE  
  ICD-10: C21.1; ICD-O: 8124/3

62-year-old female with symptoms as in case SI 16

- The specimen originates from an amputation of the rectum and shows the transition from rectal to anal mucosa.
- An undermining, partially ulcerating carcinoma can be seen in the area of the anal mucosa. This carcinoma is made up of islands of tumour cells and superficially resembles a basal cell carcinoma of the skin.
- The tumour cells are polymorph and some of the islands of tumour cells have necrotic centres.
- This is a squamous cell carcinoma which is often observed in the anal area. It is assumed that this develops from the anal transitional epithelium (not seen in this specimen). The transitional epithelium is seen as the remnants of the embryonal cloaca, hence the nomenclature "cloacogenic" carcinoma.
- Rectal glands can also be seen deep in the musculature of the sphincter.