[Comparison of clinical immunohistochemical findings in keratocystic odontogenic tumours and ameloblastomas considering their risk of recurrence].

Background: With the new term "keratocystic odontogenic tumour" (KCOT) keratocyts are even in the nomenclature a close differential diagnosis to ameloblastomas (A).

Purpose: Recurrence of KCOT and A were retrospectively compared with regard to treatment and immunohistochemical markers of cell cycle and migration and cell architecture.

Patients and methods: Biopsies harvested over a period of 22 years of 101 patients (86 KCOT, 15 A) were examined. The histopathological slides were stained with H&E and with the immunohistochemical markers: Cyclin D1, Collagen IV, p16, Cox-2-Laminin-5 and Tenascin-C.

Results: Mean age KCOT 47 years (range 14-80 years), A 41 years (range 16-79 years). Gender KCOT: m:f =2:1; A: m:f = 3:2. Region of origin mandible with predilection of the angle and the ramus: KCOT: 76; A: 12. Maxilla: KCOT: 18; A: 3. Multiple lesions were found in 5 KCOT patients. Treatment primary KCOT: cystectomy (46), cystostomy (6), cystectomy and curettage (17), cystectomy and marginal ostectomy (14), resection (11). A: resection (10), enucleation (5). Recurrence rate KCOT: 11,7% after 5,5 years. Recurrence after: cystostomy (4), cystectomy (6), cystectomy and curettage (3), cystectomy and marginal ostectomy (2). A: no recurrences. Immunohistochemistry Cell cycle associated and extracellular matrix proteins did not differ in quantity in KCOT and A, and did also not differ in recurrent and non-recurrent KCOT.

Conclusions: 1. KCOT are in the own cohort more likely recurrent than A. 2. Recurrence rate of KCOT can not be predicted by the used (most common) markers of cell cycle, migration and modulation of architecture. 3. Higher recurrence rate of KCOT in the patients examined is proposed due to less extensive resection.