The expression of
epidermal growth factor receptor (EGFr) by odontogenic epithelium was studied in
odontogenic cysts (n = 35),
ameloblastoma (n = 6), and
periapical granulomas containing proliferating epithelial rests of Malassez (n = 7) using a panel of
monoclonal antibodies to EGFr (clone E30, F4 and C11) known to react with
formalin-fixed,
paraffin-embedded sections. Odontogenic epithelium in all specimens demonstrated immunoreactivity with all three
antibodies. Clone E30 consistently gave the most intense, membrane located staining pattern of the three
antibodies tested. Generally, staining of epithelial cells progressively diminished with movement away from the basal cell layers toward the most superficial layers of cystic lining or centre of epithelial rests and tumour islands. Developmental
odontogenic cysts (odontogenic
keratocysts, n = 13;
dentigerous cysts, n = 11) and
ameloblastoma (follicular type, n = 5; unicystic type, n = 1) expressed a higher level of EGFr staining than inflammatory
cysts (radicular cysts, n = 11) and the proliferating epithelial rests in
periapical granulomas. However, foci of weak EGFr staining of odontogenic
keratocyst lining, similar to that seen in
radicular cysts, were found in areas associated with
inflammation. In addition, epithelial rests not associated with inflammatory cell infiltrates exhibited stronger reactivity for EGFr than proliferating rests within
periapical granulomas. These results indicate that the level of EGFr expression by
odontogenic cysts and rests is related to the presence of
inflammation within adjacent connective tissue and that there is no detectable difference in receptor expression between developmental
cysts and
ameloblastoma.