Stage 0
The mucosa (intestinal lining) is normal, so celiac disease is unlikely. Stage 0 is known as the "pre-infiltrative stage."
Stage 1
The cells on the surface of the intestinal lining (the epithelial cells) are being infiltrated by lymphocytes. (A lymphocyte is a small white blood cell that's involved in the body’s immune response to disease.)
Stage 2
The changes of Stage 1 are present (increased lymphocytes), and the crypts (tube-like depressions in the intestinal lining around the villi) are "hyperplastic" (larger than normal).
Stage 3
The changes of Stage 2 are present (increased lymphocytes and hyperplastic crypts), and the villi are shrinking and flattening (atrophy). There are three subsets of Stage 3:
--Partial villous atrophy (Stage 3a)
--Subtotal villous atrophy (Stage 3b)
--Total villous atrophy (Stage 3c).
Stage 4
The villi are totally atrophied (completely flattened) and the crypts are now shrunken, too.
As you'll learn on the following pages, celiac disease is not the only disorder that can cause these changes. That's why a biopsy is only one of the diagnostic tests for celiac disease, along with the results of blood tests and the patient's response to a gluten-free diet. Sources Ludvigsson JF, Brandt L, Montgomery SM, Granath F, Ekbom A. Validation study of villous atrophy and small intestinal inflammation in Swedish biopsy registers. BMC Gastroenterol. 2009;9:19. Snyder CL, Young DO, Green PHR, Taylor AK. GeneReviews: Celiac Disease. 2009
