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Cytoplasmic MSH2 immunoreactivity in a patient with Lynch syndrome with an EPCAM- MSH2 fusion.
- Source :
-
Histopathology . Mar2017, Vol. 70 Issue 4, p664-669. 6p. - Publication Year :
- 2017
-
Abstract
- Aims Immunohistochemistry for mismatch repair ( MMR) proteins is being increasingly used to examine MMR status in tumours. The aim of the present article was to report the case of a colon cancer patient with Lynch syndrome who showed unusual cytoplasmic MMR protein localization. Methods and results Histologically, the colon cancer was diagnosed as medullary carcinoma associated with prominent tumour-infiltrating lymphocytes and a Crohn's-like reaction. Immunohistochemistry revealed cytoplasmic and nuclear expression of MSH2 in non-neoplastic cells, and exclusively cytoplasmic expression in tumour cells. MSH6 expression was nuclear in non-neoplastic cells, but was lost in tumour cells. Nuclear expression of MLH1 and PMS2 was retained in both non-neoplastic and tumour cells. The tumour was microsatellite instability-high, which is indicative of defective MMR function. A subsequent germline mutation analysis identified a genomic deletion spanning the 3′ region of EPCAM and the 5′ region of MSH2, resulting in an in-frame fusion of EPCAM and MSH2. Conclusions The unusual cytoplasmic immunoreactivity of MSH2 was considered to be attributable to the non-functional EPCAM-MSH2 fusion product. The present case illustrates that not only loss of expression, but also abnormal localization, of MMR proteins is indicative of a defective MMR system. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 03090167
- Volume :
- 70
- Issue :
- 4
- Database :
- Academic Search Index
- Journal :
- Histopathology
- Publication Type :
- Academic Journal
- Accession number :
- 121183313
- Full Text :
- https://doi.org/10.1111/his.13104