Is maspin immunolocalization a tool to differentiate central low-grade mucoepidermoid carcinoma from glandular odontogenic cyst?

Summary idermoid carcinoma (MEC) of the salivary glands has a low-grade variant (LGMEC), which may be found within the jawbones. LGMEC shares a number of histopathological similarities with glandular odontogenic cysts (GOC) of the jawbones. Maspin has been identified in several benign and malignant salivary gland neoplasms. We investigated the immunolocalization of maspin in LGMEC and GOC and evaluated its potential to distinguish between these two entities. Cases of LGMEC (n=6), GOC (n=8) and various odontogenic cysts with marked mucous metaplasia (OCMM, n=7), which served as controls, were immunohistochemically labeled for the binding of an antibody directed against maspin. Immunomorphometry was performed separately for maspin-immunopositive epithelial cells and epithelial-mucous cells in either their nuclear or cytoplasmic compartments. Results were presented as the volume fraction (Vv) of each element. The Vv of the maspin-immunopositive epithelial-mucous cytoplasm and nuclei was significantly higher in LGMEC than in GOC and OCMM (p<0.001 and p=0.026, respectively). In the epithelial cells, no significant differences were observed among the lesions (p>0.05). It is suggested that the high levels of maspin in the epithelial-mucous cells (in both cytoplasm and nuclei) in LGMEC may serve as a tool to distinguish it from GOC. This may be useful especially in equivocal cases and in small incisional biopsy samples.