Colorectal Neoplasms ; genetics ; Humans ; Mass Screening ; Microsatellite Instability

OBJECTIVETo investigate the clinicopathologic features of adult-onset autoimmune enteropathy (AIE).

METHODSA case of adult-onset AIE was described along with a literature review.

RESULTSA 41-year-old male patient was admitted for intractable diarrhea for more than three months despite of any dietary restriction or anti-inflammatory therapy. Fat globule was observed by stool examination and Sudan III staining of the stool was positive. Enteroclysis showed weak movement and few plica of small intestine, while colonoscopy appeared normal. Small bowel biopsies revealed villus atrophy and increased crypt apoptotic bodies and lymphocytic infiltration in deep crypt. Although without significant surface intro-epithelial lymphocytosis, there were a large number of monocytes, lymphocytes, plasmacytes and neutrophilic granulocytes infiltrating in the lamina propria. Morphologically, the colonic mucous was similar to the small intestine although cryptitis and crypt abscess were significant in the former. Serum IgG anti-goblet cell antibody was demonstrated by indirect immunofluorescence. Other causes of diarrhea were excluded on the base of medical history, histopathology and other accessory examinations before the diagnosis of AIE was made. The patient had a complete remission after steroid treatment without recurrence for eight months during the follow-up even after steroid withdrawal for five months.

CONCLUSIONSAIE is exceedingly rare and timely diagnosis is important for successful therapy. Histological differential diagnoses should include ulcerative colitis, celiac disease, lymphocytic colitis, etc. The final diagnosis should be based on histological examination combined with the patient history, clinical manifestation, endoscopy finding and serological testing.

Atrophy ; Biopsy ; Celiac Disease ; pathology ; Colon ; pathology ; Colonoscopy ; Diagnosis, Differential ; Diarrhea ; etiology ; Humans ; Intestinal Mucosa ; pathology ; Intestine, Small ; pathology ; Lymphocytes ; Lymphocytosis ; pathology ; Polyendocrinopathies, Autoimmune ; pathology

OBJECTIVETo evaluate the sensitivity and specificity of immunohistochemical (IHC) staining of DNA mismatch repair (MMR) protein for the screening of microsatellite instability (MSI) colorectal cancer (CRC).

METHODSA total of 255 CRC cases were studied, including 140 cases of routine paraffin-embedded tissue samples and 115 cases constructed on tissue microarray. Expressions of 4 MMR proteins including MHL1, MSH2, MSH6 and PMS2 were investigated by IHC. Negative protein expression was defined as complete absence of nuclear staining within tumor cells in the presence of positively labeled internal non-neoplastic cells. Focal staining was defined as the presence of staining in < 5% of the tumor cells. CRCs showing negative staining for any MMR proteins were interpreted as MMR deficient tumors. PCR-genescan MSI analysis was performed in each case by a five marker panel including Bat26, Bat25, NR-21, NR-24 and MONO-27.

RESULTSAmong the 140 CRCs with routine formalin-fixed paraffin embedded tissue sections, concordance rate between IHC and PCR-genescan was 98.6% (138/140), the sensitivity and specificity of IHC in detecting MSI tumors were 94.9% (37/39) and 100.0% (101/101), respectively. The 2 disconcordant cases showed focal staining in at least one of the MMR proteins but were confirmed to be MSI-H CRCs by PCR-genescan assay. On tissue microarray, 91.3% (105/115) of the cases had informative results. The concordance rate between IHC and PCR-genescan was 100.0% (105/105). Both the specificity and sensitivity of IHC in detecting MSI tumors on available tissue microarray samples were 100.0%. Ten cases were inclusive due to the presence of negative stains of MMR proteins in both the tumor and internal control cells.

CONCLUSIONSDetection of 4 MMR proteins expression by IHC is reliable for identifying MSI CRCs and is recommended for routine practice. Tumors with focal MMR protein staining are highly suspected for the presence of MSI-H and PCR-genescan based MSI analysis should be performed to confirm.

Colorectal Neoplasms ; genetics ; DNA Mismatch Repair ; DNA-Binding Proteins ; deficiency ; genetics ; Humans ; Immunohistochemistry ; Microsatellite Instability ; Polymerase Chain Reaction ; Sensitivity and Specificity