Mount Sinai Hospital
600 University Avenue
Dr. Robert Riddell graduated from the University of London (St.
Bartholomew’s Hospital) in 1967, and trained in GI Pathology at St.
Mark’s and St. Bartholomew’s Hospitals in London. He moved to the
University of Chicago in 1974 and worked there for 10 years before
moving to McMaster University in Hamilton Ontario in 1984, where he was
chief of Anatomical Pathology. He moved to Mount Sinai Hospital,
Toronto, in 2001.
Dr. Riddell has almost 300 publications which are largely in
gastrointestinal pathology, primarily in inflammatory diseases,
dysplasia and carcinoma throughout the GI tact.
He has edited or written 6 books, which include the AFIP Tumors of
the Intestines, 3rd ed, and the two-volume Gastrointestinal Pathology
and its Clinical Implications, the second edition of which was
published in 2014. Dr. Riddell directs an annual week-long
gastrointestinal pathology course for the ASCP.
In 1983, Dr. Riddell was lead author on the paper defining and
grading dysplasia in inflammatory bowel disease, a system that is not
only still in use but has been extended to other parts of the
Dr. Riddell has a longstanding interest in Barrett’s esophagus, its
pathogenesis, carcinoma and dysplasia that goes back to the 1980s with
papers on dysplasia, carcinoma and its relationship to intestinal
metaplasia in Barrett’s esophagus, and regression of Barrett’s by
overgrowth of squamous mucosa.
This interest continues to the present, and most recently (2015) he
undertook a study with Drs. Elizabeth Montgomery (Johns Hopkins Dept.
of Pathology) and Michael Vieth (Bayreuth, Germany) to delineate the
specific morphological pathways in which carcinomas in Barrett’s
esophagus arise. This should allow better resolution of the problems of
dysplasia once the pathways are delineated, allow better identification
of the phenotypes of esophageal adenocarcinoma, that should in turn
allow better delineation of the molecular pathways involved in each of
Dr. Riddell set up immunohistochemistry at McMaster University, and
was Head of Immunopathology at Mount Sinai Hospital from 2001 to 2011.
Recent research includes elaborating molecular pathways using double