Electron microscopical and cytochemical studies of intestinal biopsies from a patient with
typical features of the Cronkhite-Canada syndrome show that the primary process affects the
crypts. This results in cystic dilatation associated with expansion and focal degeneration of
the crypt compartment of the intestinal epithelium. The villous epithelium compartment is
reduced but ultrastructurally normal. Inflammation and oedema of the lamina propria follows
from leakage of mucin through breaks in the abnormal crypts.