Calretinin (SP13)

Calretinin is a 29 kDa calcium-binding protein thought to play a role in the cell cycle. Anti-calretinin has been shown to be useful in differentiating mesothelioma from adenocarcinomas from the lung and other sources.1 The sensitivity of anti-calretinin in distinguishing reactive mesothelial cells from adenocarcinoma cells is 100%, and the specificity is up to 80%. Light, focal, cytoplasmic staining of adenocarcinoma cells may be seen in 10 to 30% of cases. 2 Anti-calretinin has also demonstrated utility in differentiating adrenal cortical neoplasms (+) from pheochromocytomas (-) 3, 4. Calretinin has also been useful in diagnosing granulosa cell tumor of the ovary amongst its mimics. Other ovarian tumors that stain with calretinin are Sertoli-Leydig cell tumor, Sertoli cell tumor, Leydig cell tumor, and sex cord tumor with annular tubules, as well as steroid cell tumor.5, 6-9,8