Homozygous germ-line mutation of the PMS2 mismatch repair gene: a unique case report of constitutional mismatch repair deficiency (CMMRD)

Table 1 Molecular analysis of polypoid and cancerous tumour tissue resected from the proband

Mismatch repair protein immunohistochemistry
Colorectal polypoid tissue	• >80% positivity for MLH1, MSH2 and MSH6 • Inconclusive result for PMS2 (reported poor technical quality of staining)
Ovarian tumour tissue	• >80% positivity for MLH1, MSH2, MSH6 • 0% positivity for PMS2. In addition, there was 0% positivity for PMS2 expression in control tissue
Cancer tumour characteristics
Ovarian tumour tissue	• Positive for CK7, PAX-8 and ER • MSI low
Gastric tumour tissue	• Positive for CK7, CDX2 with focal positivity for CX20 • Negative expression of ER, PR, WT1, PAX8 and GCDFP15 • There was no evidence of loss of E-cadherin expression

Molecular characteristics of the colorectal polypoid tissue, ovarian cancer tumour tissue, and gastric cancer tumour tissue resected from the proband. Initial colorectal polypoid tissue analysis was deemed inconclusive due to perceived poor technical quality of the staining due to universally absent uptake of the PMS2 antibody

ISSN: 1471-2350