Table 8 -- Bethesda Guidelines for Testing of Colorectal Tumors for Microsatellite Instability (MSI) [110]
  1. Individual with cancer in families that meet the Amsterdam Criteria
  2. Individuals with two HNPCC-related cancers, including synchronous and metachronous colorectal cancers or associated extracolonic cancer*
  3. Individuals with colorectal cancer and a first-degree relative with colorectal cancer and/or HNPCC-related extracolonic cancer and/or a colorectal adenoma: one of the cancers diagnosed at age <45 yrs, and the adenoma diagnosed at age <40
  4. Individuals with colorectal cancer or endometrial cancer diagnosed at age <45 yrs
  5. Individuals with right-sided colorectal cancer with an undifferentiated pattern (solid/cribiform) on histopathology diagnosed at age <45yrs#
  6. Individuals with signet-ring-cell-type colorectal cancer diagnosed at age <45 yrs+
  7. Individuals with adenomas diagnosed at age <40 yrs
* Endometrial, ovarian, gastric, hepatobiliary, or small-bowel cancer or transitional cell carcinoma of the renal pelvis or ureter.

# Solid/cribiform defined as poorly differentiated or undifferentiated carcinoma composed of irregular, solid sheets of large eosinophilic cells and containing small gland-like spaces.

+ Composed of >50% signet ring cells.