Calretinin expression in ameloblastomas

Aims: Calretinin is a 29-kDa calcium-binding protein which is expressed in the central and peripheral nervous systems as well as in many other normal and pathological human tissues. The objective of this study was to determin e whether calretinin was expressed in the epithelium of ameloblastomas. Methods and results: Twenty-seven cases of unicystic ameloblastoma and 31 c ases of solid and multicystic ameloblastoma were studied. Five-micron secti ons were immunohistochemically stained using either antiserum 7696 from Swa nt, or antiserum 18-0211 from Zymed with a standard ABC method. The results were identical with the two antisera. Positive staining was seen in 22 cas es (81.5%) of unicystic ameloblastomas. This generally consisted of diffuse , intense nuclear and cytoplasmic staining of several cell layers of the mo re superficial cells both in the characteristic and non-descript areas of t he cyst linings. In the solid and multicystic ameloblastomas, staining occu rred in 29 (93.5%) of the cases. The staining was almost always restricted to the stellate reticulum-like epithelium, was generally intense and diffus e in distribution. Areas of squamous metaplasia stained particularly intens ely as did the cells surrounding micro- and macro-cysts. In both groups of lesions, most of the cases that did not stain were intensely inflamed. Conclusions: The biological significance of calretinin expression in amelob lastomas is not known and its use as a distinctive, specific immunohistoche mical marker for ameloblastic tissues remains to be confirmed. However, the results of this study raise the possibility that calretinin may be an impo rtant diagnostic aid in the differential diagnosis of cystic and solid amel oblastic tumours.