Expression of podoplanin in nevoid basal cell carcinoma syndrome-associated keratocystic odontogenic tumours.

BACKGROUND: Keratocystic odontogenic tumour (KCOT) is a benign oral neoplasm of odontogenic origin. The majority of KCOT develop sporadically. The main differential diagnosis of KCOT is from other odontogenic cysts and ameloblastoma. In the rare nevoid basal cell carcinoma syndrome (NBCCS, synonym: Gorlin(-Goltz)-Syndrome), however, KCOTs are frequently detected and may be the initial sign of this clinical syndrome. Podoplanin is a mucin-type transmembrane protein found in podocytes of human kidneys homologous to T1α-2. The expression of podoplanin in some other non-endothelial tissues raised our interest in studying this antibody in tissues of odontogenic origin. Recently, we reported podoplanin expression in sporadic cases of KCOT. We intended to investigate the podoplanin expression in KCOTs associated with NBCCS.

MATERIALS AND METHODS: Archival paraffin embedded tissues from six KCOTs from patients with known NBCCCS were analyzed immunohistochemically with antibodies to podoplanin (D2-40) and p63.

RESULTS: We observed a continuous linear immunoreactivity of basal epithelial cells for podoplanin in all cases. The staining intensity was strong and did not differ from that for KCOT in previously reported sporadic cases. Strong nuclear P63 expression was detected in basal cell layers and diminished in suprabasal layers.

CONCLUSION: KCOTs exhibited enhanced podoplanin expression in a clinical setting of NBCCS. Although the biological functions of podoplanin have not yet been fully recognized, the overexpression of this protein is capable of promoting the formation of elongated cell extensions, and increasing adhesion and migration of inflammatory cells. Podoplanin expression in KCOT is possibly associated with slow invasion of the adjacent structures and the well-known frequent local tumour recurrences of this odontogenic tumour.