Increased alpha-B-crystallin expression in mammary metaplastic carcinomas

Chan S‐K, Lui P C W, Tan P‐H, Yamaguchi R, Moriya T, Yu A M C, Shao M‐M, Hliang T, Wong S‐I & Tse G M (2011) Histopathology59, 247–255 Increased alpha‐B‐crystallin expression in mammary metaplastic carcinomas Aims: Mammary metaplastic carcinoma is a rare breast carcinoma, and may present diagnostic difficulty. Alpha‐B‐crystallin has been recently reported to be expressed in basal‐like and metaplastic carcinomas. Methods and results: Thirty‐three metaplastic carcinomas, 44 conventional high‐grade carcinomas and 28 mesenchymal spindle cell neoplasms as controls were assessed for their expression of αB‐crystallin and conventional basal‐like phenotypic markers CK5/6, CK14, p63, c‐kit and epidermal growth factor receptor (EGFR) by immunohistochemistry. Alpha‐B‐crystallin staining was positive in 68% of the metaplastic carcinomas with cytoplasmic staining in all tumour cell components. CK5/6, CK14, p63, c‐kit and EGFR stained 43%, 68%, 45%, 21% and 25% of the metaplastic carcinomas, respectively. Combining these markers, 84% of the metaplastic carcinomas expressed either αB‐crystallin or CK14. In comparison, only 14% (six cases) of conventional high‐grade carcinoma and 7% (two cases) of mesenchymal spindle cell neoplasm expressed αB‐crystallin; all but one of these carcinomas were ER/PR/HER2 triple‐negative. Conclusions: Using αB‐crystallin for diagnosis of metaplastic carcinoma gives a 68% sensitivity, 88% specificity, 74% positive predictive value, 85% negative predictive value and 78% accuracy. The sensitivity is enhanced to 84% with combinations of αB‐crystallin/CK14. Alpha‐B‐crystallin may be used as an adjunct marker in the diagnosis of metaplastic carcinoma.