Calretinin

Calretinin is a very sensitive marker used most commonly as a positive marker for mesothelioma.  It is expressed in >80% of epithelial and up to 70% of sarcomatous subtypes, staining in a cytoplasmic and nuclear pattern.  It is recommended to be used as part of a panel (2 mesothelial markers and 2 adenocarcinoma markers) since there are no sensitive and specific markers to differentiate mesothelioma from adenocarcinoma.
Other tumors expressing Calretinin
  • Sex-cord stromal tumors
  • Adrenal cortical tumors
  • Rare adenocarcinomas
  • Rare squamous cell carcinomas
Photomicrographs
Calretinin - Mesothelium
Chronically inflamed mesothelium highlighted by calretinin.
Calretinin - Mesothelium
Benign mesothelium highlighted by calretinin.
References 
Arch Pathol Lab Med- Vol. 134, February 2010 p. 208.
Wick, MR. “Immunohistochemical approaches to the diagnosis of undifferentiated malignant tumor.”Annals of Diagnostic Pathology12(2008):72-84.